Viewing github.com/django/django-stable-4.1.x/docs/ref/contrib/gis/gdal.txt

```
========
```
```
GDAL API
```
```
========
```
```
.. module:: django.contrib.gis.gdal
```

    :synopsis: GeoDjango's high-level interface to the GDAL library.

`GDAL`__ stands for **Geospatial Data Abstraction Library**,

and is a veritable "Swiss army knife" of GIS data functionality.  A subset

of GDAL is the `OGR`__ Simple Features Library, which specializes

in reading and writing vector geographic data in a variety of standard

```
formats.
```

GeoDjango provides a high-level Python interface for some of the

capabilities of OGR, including the reading and coordinate transformation

of vector spatial data and minimal support for GDAL's features with respect

```
to raster (image) data.
```
```
.. note::
```

    Although the module is named ``gdal``, GeoDjango only supports some of the

    capabilities of OGR and GDAL's raster features at this time.

```
__ https://gdal.org/
```

__ https://gdal.org/user/vector_data_model.html

```
Overview
```
```
========
```
```
.. _gdal_sample_data:
```
```
Sample Data
```
```
-----------
```

The GDAL/OGR tools described here are designed to help you read in

your geospatial data, in order for most of them to be useful you have

to have some data to work with.  If you're starting out and don't yet

have any data of your own to use, GeoDjango tests contain a number of

data sets that you can use for testing. You can download them here::

    $ wget https://raw.githubusercontent.com/django/django/main/tests/gis_tests/data/cities/cities.{shp,prj,shx,dbf}

    $ wget https://raw.githubusercontent.com/django/django/main/tests/gis_tests/data/rasters/raster.tif

```
Vector Data Source Objects
```
```
==========================
```
```
``DataSource``
```
```
--------------
```

:class:`DataSource` is a wrapper for the OGR data source object that

supports reading data from a variety of OGR-supported geospatial file

formats and data sources using a consistent interface.  Each

data source is represented by a :class:`DataSource` object which contains

one or more layers of data.  Each layer, represented by a :class:`Layer`

object, contains some number of geographic features (:class:`Feature`),

information about the type of features contained in that layer (e.g.

points, polygons, etc.), as well as the names and types of any

additional fields (:class:`Field`) of data that may be associated with

```
each feature in that layer.
```

.. class:: DataSource(ds_input, encoding='utf-8')

    The constructor for ``DataSource`` only requires one parameter: the path of

    the file you want to read. However, OGR also supports a variety of more

    complex data sources, including databases, that may be accessed by passing

    a special name string instead of a path. For more information, see the

    `OGR Vector Formats`__ documentation. The :attr:`name` property of a

    ``DataSource`` instance gives the OGR name of the underlying data source

```
    that it is using.
```

    The optional ``encoding`` parameter allows you to specify a non-standard

    encoding of the strings in the source. This is typically useful when you

    obtain ``DjangoUnicodeDecodeError`` exceptions while reading field values.

    Once you've created your ``DataSource``, you can find out how many layers

    of data it contains by accessing the :attr:`layer_count` property, or

    (equivalently) by using the ``len()`` function. For information on

    accessing the layers of data themselves, see the next section::

        >>> from django.contrib.gis.gdal import DataSource

        >>> ds = DataSource('/path/to/your/cities.shp')

```
        >>> ds.name
```
```
        '/path/to/your/cities.shp'
```

        >>> ds.layer_count                  # This file only contains one layer

```
        1
```
```
    .. attribute:: layer_count
```

    Returns the number of layers in the data source.

```
    .. attribute:: name
```

    Returns the name of the data source.

```
__ https://gdal.org/drivers/vector/
```
```
``Layer``
```
```
---------
```
```
.. class:: Layer
```

    ``Layer`` is a wrapper for a layer of data in a ``DataSource`` object. You

    never create a ``Layer`` object directly. Instead, you retrieve them from

    a :class:`DataSource` object, which is essentially a standard Python

    container of ``Layer`` objects. For example, you can access a specific

    layer by its index (e.g. ``ds[0]`` to access the first layer), or you can

    iterate over all the layers in the container in a ``for`` loop. The

    ``Layer`` itself acts as a container for geometric features.

    Typically, all the features in a given layer have the same geometry type.

    The :attr:`geom_type` property of a layer is an :class:`OGRGeomType` that

    identifies the feature type. We can use it to print out some basic

    information about each layer in a :class:`DataSource`::

```
        >>> for layer in ds:
```

        ...     print('Layer "%s": %i %ss' % (layer.name, len(layer), layer.geom_type.name))

```
        ...
```
```
        Layer "cities": 3 Points
```

    The example output is from the cities data source, loaded above, which

    evidently contains one layer, called ``"cities"``, which contains three

    point features. For simplicity, the examples below assume that you've

    stored that layer in the variable ``layer``::

```
        >>> layer = ds[0]
```
```
    .. attribute:: name
```

    Returns the name of this layer in the data source.

```
        >>> layer.name
```
```
        'cities'
```
```
    .. attribute:: num_feat
```

    Returns the number of features in the layer. Same as ``len(layer)``::

```
        >>> layer.num_feat
```
```
        3
```
```
    .. attribute:: geom_type
```

    Returns the geometry type of the layer, as an :class:`OGRGeomType` object::

```
        >>> layer.geom_type.name
```
```
        'Point'
```
```
    .. attribute:: num_fields
```

    Returns the number of fields in the layer, i.e the number of fields of

    data associated with each feature in the layer::

```
        >>> layer.num_fields
```
```
        4
```
```
    .. attribute:: fields
```

    Returns a list of the names of each of the fields in this layer::

```
        >>> layer.fields
```

        ['Name', 'Population', 'Density', 'Created']

```
    .. attribute field_types
```

    Returns a list of the data types of each of the fields in this layer. These

    are subclasses of ``Field``, discussed below::

        >>> [ft.__name__ for ft in layer.field_types]

        ['OFTString', 'OFTReal', 'OFTReal', 'OFTDate']

```
    .. attribute:: field_widths
```

    Returns a list of the maximum field widths for each of the fields in this

```
    layer::
```
```
        >>> layer.field_widths
```
```
        [80, 11, 24, 10]
```
```
    .. attribute:: field_precisions
```

    Returns a list of the numeric precisions for each of the fields in this

    layer. This is meaningless (and set to zero) for non-numeric fields::

```
        >>> layer.field_precisions
```
```
        [0, 0, 15, 0]
```
```
    .. attribute:: extent
```

    Returns the spatial extent of this layer, as an :class:`Envelope` object::

```
        >>> layer.extent.tuple
```

        (-104.609252, 29.763374, -95.23506, 38.971823)

```
    .. attribute:: srs
```

    Property that returns the :class:`SpatialReference` associated with this

```
    layer::
```
```
        >>> print(layer.srs)
```
```
        GEOGCS["GCS_WGS_1984",
```
```
            DATUM["WGS_1984",
```

                SPHEROID["WGS_1984",6378137,298.257223563]],

```
            PRIMEM["Greenwich",0],
```

            UNIT["Degree",0.017453292519943295]]

    If the :class:`Layer` has no spatial reference information associated

```
    with it, ``None`` is returned.
```
```
    .. attribute:: spatial_filter
```

    Property that may be used to retrieve or set a spatial filter for this

    layer. A spatial filter can only be set with an :class:`OGRGeometry`

    instance, a 4-tuple extent, or ``None``. When set with something other than

    ``None``, only features that intersect the filter will be returned when

```
    iterating over the layer::
```

        >>> print(layer.spatial_filter)

```
        None
```
```
        >>> print(len(layer))
```
```
        3
```

        >>> [feat.get('Name') for feat in layer]

        ['Pueblo', 'Lawrence', 'Houston']

        >>> ks_extent = (-102.051, 36.99, -94.59, 40.00) # Extent for state of Kansas

        >>> layer.spatial_filter = ks_extent

```
        >>> len(layer)
```
```
        1
```

        >>> [feat.get('Name') for feat in layer]

```
        ['Lawrence']
```

        >>> layer.spatial_filter = None

```
        >>> len(layer)
```
```
        3
```
```
    .. method:: get_fields()
```

    A method that returns a list of the values of a given field for each

```
    feature in the layer::
```
```
        >>> layer.get_fields('Name')
```

        ['Pueblo', 'Lawrence', 'Houston']

```
    .. method:: get_geoms(geos=False)
```

    A method that returns a list containing the geometry of each feature in the

    layer. If the optional argument ``geos`` is set to ``True`` then the

    geometries are converted to :class:`~django.contrib.gis.geos.GEOSGeometry`

    objects. Otherwise, they are returned as :class:`OGRGeometry` objects::

        >>> [pt.tuple for pt in layer.get_geoms()]

        [(-104.609252, 38.255001), (-95.23506, 38.971823), (-95.363151, 29.763374)]

    .. method:: test_capability(capability)

    Returns a boolean indicating whether this layer supports the given

    capability (a string).  Examples of valid capability strings include:

    ``'RandomRead'``, ``'SequentialWrite'``, ``'RandomWrite'``,

    ``'FastSpatialFilter'``, ``'FastFeatureCount'``, ``'FastGetExtent'``,

    ``'CreateField'``, ``'Transactions'``, ``'DeleteFeature'``, and

```
    ``'FastSetNextByIndex'``.
```
```
``Feature``
```
```
-----------
```
```
.. class:: Feature
```

    ``Feature`` wraps an OGR feature. You never create a ``Feature`` object

    directly. Instead, you retrieve them from a :class:`Layer` object. Each

    feature consists of a geometry and a set of fields containing additional

    properties. The geometry of a field is accessible via its ``geom`` property,

    which returns an :class:`OGRGeometry` object. A ``Feature`` behaves like a

    standard Python container for its fields, which it returns as :class:`Field`

    objects: you can access a field directly by its index or name, or you can

    iterate over a feature's fields, e.g. in a ``for`` loop.

```
    .. attribute:: geom
```

    Returns the geometry for this feature, as an ``OGRGeometry`` object::

```
        >>> city.geom.tuple
```
```
        (-104.609252, 38.255001)
```
```
    .. attribute:: get
```

    A method that returns the value of the given field (specified by name)

    for this feature, **not** a ``Field`` wrapper object::

```
        >>> city.get('Population')
```
```
        102121
```
```
    .. attribute:: geom_type
```

    Returns the type of geometry for this feature, as an :class:`OGRGeomType`

    object. This will be the same for all features in a given layer and is

    equivalent to the :attr:`Layer.geom_type` property of the :class:`Layer`

```
    object the feature came from.
```
```
    .. attribute:: num_fields
```

    Returns the number of fields of data associated with the feature. This will

    be the same for all features in a given layer and is equivalent to the

    :attr:`Layer.num_fields` property of the :class:`Layer` object the feature

```
    came from.
```
```
    .. attribute:: fields
```

    Returns a list of the names of the fields of data associated with the

    feature. This will be the same for all features in a given layer and is

    equivalent to the :attr:`Layer.fields` property of the :class:`Layer`

```
    object the feature came from.
```
```
    .. attribute:: fid
```

    Returns the feature identifier within the layer::

```
        >>> city.fid
```
```
        0
```
```
    .. attribute:: layer_name
```

    Returns the name of the :class:`Layer` that the feature came from. This

    will be the same for all features in a given layer::

```
        >>> city.layer_name
```
```
        'cities'
```
```
    .. attribute:: index
```

    A method that returns the index of the given field name. This will be the

    same for all features in a given layer::

```
        >>> city.index('Population')
```
```
        1
```
```
``Field``
```
```
---------
```
```
.. class:: Field
```
```
    .. attribute:: name
```
```
    Returns the name of this field::
```
```
        >>> city['Name'].name
```
```
        'Name'
```
```
    .. attribute:: type
```

    Returns the OGR type of this field, as an integer. The ``FIELD_CLASSES``

    dictionary maps these values onto subclasses of ``Field``::

```
        >>> city['Density'].type
```
```
        2
```
```
    .. attribute:: type_name
```

    Returns a string with the name of the data type of this field::

```
        >>> city['Name'].type_name
```
```
        'String'
```
```
    .. attribute:: value
```

    Returns the value of this field. The ``Field`` class itself returns the

    value as a string, but each subclass returns the value in the most

```
    appropriate form::
```
```
        >>> city['Population'].value
```
```
        102121
```
```
    .. attribute:: width
```
```
    Returns the width of this field::
```
```
        >>> city['Name'].width
```
```
        80
```
```
    .. attribute:: precision
```

    Returns the numeric precision of this field. This is meaningless (and set

```
    to zero) for non-numeric fields::
```
```
        >>> city['Density'].precision
```
```
        15
```
```
    .. method:: as_double()
```

    Returns the value of the field as a double (float)::

        >>> city['Density'].as_double()

```
        874.7
```
```
    .. method:: as_int()
```

    Returns the value of the field as an integer::

        >>> city['Population'].as_int()

```
        102121
```
```
    .. method:: as_string()
```

    Returns the value of the field as a string::

```
        >>> city['Name'].as_string()
```
```
        'Pueblo'
```
```
    .. method:: as_datetime()
```

    Returns the value of the field as a tuple of date and time components::

        >>> city['Created'].as_datetime()

        (c_long(1999), c_long(5), c_long(23), c_long(0), c_long(0), c_long(0), c_long(0))

```
``Driver``
```
```
----------
```
```
.. class:: Driver(dr_input)
```

    The ``Driver`` class is used internally to wrap an OGR :class:`DataSource`

```
    driver.
```
```
    .. attribute:: driver_count
```

    Returns the number of OGR vector drivers currently registered.

```
OGR Geometries
```
```
==============
```
```
``OGRGeometry``
```
```
---------------
```

:class:`OGRGeometry` objects share similar functionality with

:class:`~django.contrib.gis.geos.GEOSGeometry` objects and are thin wrappers

around OGR's internal geometry representation. Thus, they allow for more

efficient access to data when using :class:`DataSource`. Unlike its GEOS

counterpart, :class:`OGRGeometry` supports spatial reference systems and

```
coordinate transformation::
```

    >>> from django.contrib.gis.gdal import OGRGeometry

    >>> polygon = OGRGeometry('POLYGON((0 0, 5 0, 5 5, 0 5))')

.. class:: OGRGeometry(geom_input, srs=None)

    This object is a wrapper for the `OGR Geometry`__ class. These objects are

    instantiated directly from the given ``geom_input`` parameter, which may be

    a string containing WKT, HEX, GeoJSON, a ``buffer`` containing WKB data, or

    an :class:`OGRGeomType` object. These objects are also returned from the

    :class:`Feature.geom` attribute, when reading vector data from

    :class:`Layer` (which is in turn a part of a :class:`DataSource`).

    __ https://gdal.org/api/ogrgeometry_cpp.html#ogrgeometry-class

    .. classmethod:: from_gml(gml_string)

    Constructs an :class:`OGRGeometry` from the given GML string.

```
    .. classmethod:: from_bbox(bbox)
```

    Constructs a :class:`Polygon` from the given bounding-box (a 4-tuple).

```
    .. method:: __len__()
```

    Returns the number of points in a :class:`LineString`, the number of rings

    in a :class:`Polygon`, or the number of geometries in a

    :class:`GeometryCollection`. Not applicable to other geometry types.

```
    .. method:: __iter__()
```

    Iterates over the points in a :class:`LineString`, the rings in a

    :class:`Polygon`, or the geometries in a :class:`GeometryCollection`.

    Not applicable to other geometry types.

```
    .. method:: __getitem__()
```

    Returns the point at the specified index for a :class:`LineString`, the

    interior ring at the specified index for a :class:`Polygon`, or the geometry

    at the specified index in a :class:`GeometryCollection`. Not applicable to

```
    other geometry types.
```
```
    .. attribute:: dimension
```

    Returns the number of coordinated dimensions of the geometry, i.e. 0

    for points, 1 for lines, and so forth::

```
        >> polygon.dimension
```
```
        2
```
```
    .. attribute:: coord_dim
```

    Returns or sets the coordinate dimension of this geometry. For example, the

    value would be 2 for two-dimensional geometries.

```
    .. attribute:: geom_count
```

    Returns the number of elements in this geometry::

```
        >>> polygon.geom_count
```
```
        1
```
```
    .. attribute:: point_count
```

    Returns the number of points used to describe this geometry::

```
        >>> polygon.point_count
```
```
        4
```
```
    .. attribute:: num_points
```
```
    Alias for :attr:`point_count`.
```
```
    .. attribute:: num_coords
```
```
    Alias for :attr:`point_count`.
```
```
    .. attribute:: geom_type
```

    Returns the type of this geometry, as an :class:`OGRGeomType` object.

```
    .. attribute:: geom_name
```

    Returns the name of the type of this geometry::

```
        >>> polygon.geom_name
```
```
        'POLYGON'
```
```
    .. attribute:: area
```

    Returns the area of this geometry, or 0 for geometries that do not contain

```
    an area::
```
```
        >>> polygon.area
```
```
        25.0
```
```
    .. attribute:: envelope
```

    Returns the envelope of this geometry, as an :class:`Envelope` object.

```
    .. attribute:: extent
```

    Returns the envelope of this geometry as a 4-tuple, instead of as an

```
    :class:`Envelope` object::
```
```
        >>> point.extent
```
```
        (0.0, 0.0, 5.0, 5.0)
```
```
    .. attribute:: srs
```

    This property controls the spatial reference for this geometry, or

    ``None`` if no spatial reference system has been assigned to it.

    If assigned, accessing this property returns a :class:`SpatialReference`

    object.  It may be set with another :class:`SpatialReference` object,

    or any input that :class:`SpatialReference` accepts. Example::

```
        >>> city.geom.srs.name
```
```
        'GCS_WGS_1984'
```
```
    .. attribute:: srid
```

    Returns or sets the spatial reference identifier corresponding to

    :class:`SpatialReference` of this geometry.  Returns ``None`` if

    there is no spatial reference information associated with this

    geometry, or if an SRID cannot be determined.

```
    .. attribute:: geos
```

    Returns a :class:`~django.contrib.gis.geos.GEOSGeometry` object

```
    corresponding to this geometry.
```
```
    .. attribute:: gml
```

    Returns a string representation of this geometry in GML format::

        >>> OGRGeometry('POINT(1 2)').gml

        '<gml:Point><gml:coordinates>1,2</gml:coordinates></gml:Point>'

```
    .. attribute:: hex
```

    Returns a string representation of this geometry in HEX WKB format::

        >>> OGRGeometry('POINT(1 2)').hex

        '0101000000000000000000F03F0000000000000040'

```
    .. attribute:: json
```

    Returns a string representation of this geometry in JSON format::

        >>> OGRGeometry('POINT(1 2)').json

        '{ "type": "Point", "coordinates": [ 1.000000, 2.000000 ] }'

```
    .. attribute:: kml
```

    Returns a string representation of this geometry in KML format.

```
    .. attribute:: wkb_size
```

    Returns the size of the WKB buffer needed to hold a WKB representation

```
    of this geometry::
```

        >>> OGRGeometry('POINT(1 2)').wkb_size

```
        21
```
```
    .. attribute:: wkb
```

    Returns a ``buffer`` containing a WKB representation of this geometry.

```
    .. attribute:: wkt
```

    Returns a string representation of this geometry in WKT format.

```
    .. attribute:: ewkt
```

    Returns the EWKT representation of this geometry.

```
    .. method:: clone()
```

    Returns a new :class:`OGRGeometry` clone of this geometry object.

```
    .. method:: close_rings()
```

    If there are any rings within this geometry that have not been closed,

    this routine will do so by adding the starting point to the end::

        >>> triangle = OGRGeometry('LINEARRING (0 0,0 1,1 0)')

```
        >>> triangle.close_rings()
```
```
        >>> triangle.wkt
```
```
        'LINEARRING (0 0,0 1,1 0,0 0)'
```

    .. method:: transform(coord_trans, clone=False)

    Transforms this geometry to a different spatial reference system. May take

    a :class:`CoordTransform` object, a :class:`SpatialReference` object, or

    any other input accepted by :class:`SpatialReference` (including spatial

    reference WKT and PROJ strings, or an integer SRID).

    By default nothing is returned and the geometry is transformed in-place.

    However, if the ``clone`` keyword is set to ``True`` then a transformed

    clone of this geometry is returned instead.

```
    .. method:: intersects(other)
```

    Returns ``True`` if this geometry intersects the other, otherwise returns

```
    ``False``.
```
```
    .. method:: equals(other)
```

    Returns ``True`` if this geometry is equivalent to the other, otherwise

```
    returns ``False``.
```
```
    .. method:: disjoint(other)
```

    Returns ``True`` if this geometry is spatially disjoint to (i.e. does

    not intersect) the other, otherwise returns ``False``.

```
    .. method:: touches(other)
```

    Returns ``True`` if this geometry touches the other, otherwise returns

```
    ``False``.
```
```
    .. method:: crosses(other)
```

    Returns ``True`` if this geometry crosses the other, otherwise returns

```
    ``False``.
```
```
    .. method:: within(other)
```

    Returns ``True`` if this geometry is contained within the other, otherwise

```
    returns ``False``.
```
```
    .. method:: contains(other)
```

    Returns ``True`` if this geometry contains the other, otherwise returns

```
    ``False``.
```
```
    .. method:: overlaps(other)
```

    Returns ``True`` if this geometry overlaps the other, otherwise returns

```
    ``False``.
```
```
    .. method:: boundary()
```

    The boundary of this geometry, as a new :class:`OGRGeometry` object.

```
    .. attribute:: convex_hull
```

    The smallest convex polygon that contains this geometry, as a new

```
    :class:`OGRGeometry` object.
```
```
    .. method:: difference()
```

    Returns the region consisting of the difference of this geometry and

    the other, as a new :class:`OGRGeometry` object.

```
    .. method:: intersection()
```

    Returns the region consisting of the intersection of this geometry and

    the other, as a new :class:`OGRGeometry` object.

```
    .. method:: sym_difference()
```

    Returns the region consisting of the symmetric difference of this

    geometry and the other, as a new :class:`OGRGeometry` object.

```
    .. method:: union()
```

    Returns the region consisting of the union of this geometry and

    the other, as a new :class:`OGRGeometry` object.

```
    .. attribute:: tuple
```

    Returns the coordinates of a point geometry as a tuple, the

    coordinates of a line geometry as a tuple of tuples, and so forth::

        >>> OGRGeometry('POINT (1 2)').tuple

```
        (1.0, 2.0)
```

        >>> OGRGeometry('LINESTRING (1 2,3 4)').tuple

```
        ((1.0, 2.0), (3.0, 4.0))
```
```
    .. attribute:: coords
```
```
    An alias for :attr:`tuple`.
```
```
.. class:: Point
```
```
    .. attribute:: x
```

    Returns the X coordinate of this point::

        >>> OGRGeometry('POINT (1 2)').x

```
        1.0
```
```
    .. attribute:: y
```

    Returns the Y coordinate of this point::

        >>> OGRGeometry('POINT (1 2)').y

```
        2.0
```
```
    .. attribute:: z
```

    Returns the Z coordinate of this point, or ``None`` if the point does not

```
    have a Z coordinate::
```

        >>> OGRGeometry('POINT (1 2 3)').z

```
        3.0
```
```
.. class:: LineString
```
```
    .. attribute:: x
```

    Returns a list of X coordinates in this line::

        >>> OGRGeometry('LINESTRING (1 2,3 4)').x

```
        [1.0, 3.0]
```
```
    .. attribute:: y
```

    Returns a list of Y coordinates in this line::

        >>> OGRGeometry('LINESTRING (1 2,3 4)').y

```
        [2.0, 4.0]
```
```
    .. attribute:: z
```

    Returns a list of Z coordinates in this line, or ``None`` if the line does

```
    not have Z coordinates::
```

        >>> OGRGeometry('LINESTRING (1 2 3,4 5 6)').z

```
        [3.0, 6.0]
```
```
.. class:: Polygon
```
```
    .. attribute:: shell
```

    Returns the shell or exterior ring of this polygon, as a ``LinearRing``

```
    geometry.
```
```
    .. attribute:: exterior_ring
```
```
    An alias for :attr:`shell`.
```
```
    .. attribute:: centroid
```

    Returns a :class:`Point` representing the centroid of this polygon.

```
.. class:: GeometryCollection
```
```
    .. method:: add(geom)
```

    Adds a geometry to this geometry collection. Not applicable to other

```
    geometry types.
```
```
``OGRGeomType``
```
```
---------------
```
```
.. class:: OGRGeomType(type_input)
```

    This class allows for the representation of an OGR geometry type

```
    in any of several ways::
```

        >>> from django.contrib.gis.gdal import OGRGeomType

        >>> gt1 = OGRGeomType(3)             # Using an integer for the type

        >>> gt2 = OGRGeomType('Polygon')     # Using a string

        >>> gt3 = OGRGeomType('POLYGON')     # It's case-insensitive

        >>> print(gt1 == 3, gt1 == 'Polygon') # Equivalence works w/non-OGRGeomType objects

```
        True True
```
```
    .. attribute:: name
```

    Returns a short-hand string form of the OGR Geometry type::

```
        >>> gt1.name
```
```
        'Polygon'
```
```
    .. attribute:: num
```

    Returns the number corresponding to the OGR geometry type::

```
        >>> gt1.num
```
```
        3
```
```
    .. attribute:: django
```

    Returns the Django field type (a subclass of GeometryField) to use for

    storing this OGR type, or ``None`` if there is no appropriate Django type::

```
        >>> gt1.django
```
```
        'PolygonField'
```
```
``Envelope``
```
```
------------
```
```
.. class:: Envelope(*args)
```

    Represents an OGR Envelope structure that contains the minimum and maximum

    X, Y coordinates for a rectangle bounding box. The naming of the variables

    is compatible with the OGR Envelope C structure.

```
    .. attribute:: min_x
```

    The value of the minimum X coordinate.

```
    .. attribute:: min_y
```

    The value of the maximum X coordinate.

```
    .. attribute:: max_x
```

    The value of the minimum Y coordinate.

```
    .. attribute:: max_y
```

    The value of the maximum Y coordinate.

```
    .. attribute:: ur
```

    The upper-right coordinate, as a tuple.

```
    .. attribute:: ll
```

    The lower-left coordinate, as a tuple.

```
    .. attribute:: tuple
```
```
    A tuple representing the envelope.
```
```
    .. attribute:: wkt
```

    A string representing this envelope as a polygon in WKT format.

    .. method:: expand_to_include(*args)

```
Coordinate System Objects
```
```
=========================
```
```
``SpatialReference``
```
```
--------------------
```
```
.. class:: SpatialReference(srs_input)
```

    Spatial reference objects are initialized on the given ``srs_input``,

```
    which may be one of the following:
```

    * OGC Well Known Text (WKT) (a string)

```
    * EPSG code (integer or string)
```
```
    * PROJ string
```

    * A shorthand string for well-known standards (``'WGS84'``, ``'WGS72'``,

```
      ``'NAD27'``, ``'NAD83'``)
```
```
    Example::
```

        >>> wgs84 = SpatialReference('WGS84') # shorthand string

        >>> wgs84 = SpatialReference(4326) # EPSG code

        >>> wgs84 = SpatialReference('EPSG:4326') # EPSG string

        >>> proj = '+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs '

        >>> wgs84 = SpatialReference(proj) # PROJ string

        >>> wgs84 = SpatialReference("""GEOGCS["WGS 84",

```
        DATUM["WGS_1984",
```

             SPHEROID["WGS 84",6378137,298.257223563,

                 AUTHORITY["EPSG","7030"]],

             AUTHORITY["EPSG","6326"]],

```
         PRIMEM["Greenwich",0,
```

             AUTHORITY["EPSG","8901"]],

         UNIT["degree",0.01745329251994328,

             AUTHORITY["EPSG","9122"]],

         AUTHORITY["EPSG","4326"]]""") # OGC WKT

```
    .. method:: __getitem__(target)
```

    Returns the value of the given string attribute node, ``None`` if the node

    doesn't exist. Can also take a tuple as a parameter, (target, child), where

    child is the index of the attribute in the WKT. For example::

        >>> wkt = 'GEOGCS["WGS 84", DATUM["WGS_1984, ... AUTHORITY["EPSG","4326"]]')

        >>> srs = SpatialReference(wkt) # could also use 'WGS84', or 4326

```
        >>> print(srs['GEOGCS'])
```
```
        WGS 84
```
```
        >>> print(srs['DATUM'])
```
```
        WGS_1984
```
```
        >>> print(srs['AUTHORITY'])
```
```
        EPSG
```

        >>> print(srs['AUTHORITY', 1]) # The authority value

```
        4326
```

        >>> print(srs['TOWGS84', 4]) # the fourth value in this wkt

```
        0
```

        >>> print(srs['UNIT|AUTHORITY']) # For the units authority, have to use the pipe symbol.

```
        EPSG
```

        >>> print(srs['UNIT|AUTHORITY', 1]) # The authority value for the units

```
        9122
```

    .. method:: attr_value(target, index=0)

    The attribute value for the given target node (e.g. ``'PROJCS'``).

    The index keyword specifies an index of the child node to return.

```
    .. method:: auth_name(target)
```

    Returns the authority name for the given string target node.

```
    .. method:: auth_code(target)
```

    Returns the authority code for the given string target node.

```
    .. method:: clone()
```

    Returns a clone of this spatial reference object.

```
    .. method:: identify_epsg()
```

    This method inspects the WKT of this ``SpatialReference`` and will add EPSG

    authority nodes where an EPSG identifier is applicable.

```
    .. method:: from_esri()
```

    Morphs this SpatialReference from ESRI's format to EPSG

```
    .. method:: to_esri()
```

    Morphs this SpatialReference to ESRI's format.

```
    .. method:: validate()
```

    Checks to see if the given spatial reference is valid, if not

```
    an exception will be raised.
```
```
    .. method:: import_epsg(epsg)
```

    Import spatial reference from EPSG code.

```
    .. method:: import_proj(proj)
```

    Import spatial reference from PROJ string.

    .. method:: import_user_input(user_input)

```
    .. method:: import_wkt(wkt)
```
```
    Import spatial reference from WKT.
```
```
    .. method:: import_xml(xml)
```
```
    Import spatial reference from XML.
```
```
    .. attribute:: name
```

    Returns the name of this Spatial Reference.

```
    .. attribute:: srid
```

    Returns the SRID of top-level authority, or ``None`` if undefined.

```
    .. attribute:: linear_name
```

    Returns the name of the linear units.

```
    .. attribute:: linear_units
```

    Returns the value of the linear units.

```
    .. attribute:: angular_name
```

    Returns the name of the angular units."

```
    .. attribute:: angular_units
```

    Returns the value of the angular units.

```
    .. attribute:: units
```

    Returns a 2-tuple of the units value and the units name and will

    automatically determines whether to return the linear or angular units.

```
    .. attribute:: ellipsoid
```

    Returns a tuple of the ellipsoid parameters for this spatial reference:

    (semimajor axis, semiminor axis, and inverse flattening).

```
    .. attribute:: semi_major
```

    Returns the semi major axis of the ellipsoid for this spatial reference.

```
    .. attribute:: semi_minor
```

    Returns the semi minor axis of the ellipsoid for this spatial reference.

```
    .. attribute:: inverse_flattening
```

    Returns the inverse flattening of the ellipsoid for this spatial reference.

```
    .. attribute:: geographic
```

    Returns ``True`` if this spatial reference is geographic (root node is

```
    ``GEOGCS``).
```
```
    .. attribute:: local
```

    Returns ``True`` if this spatial reference is local (root node is

```
    ``LOCAL_CS``).
```
```
    .. attribute:: projected
```

    Returns ``True`` if this spatial reference is a projected coordinate system

```
    (root node is ``PROJCS``).
```
```
    .. attribute:: wkt
```

    Returns the WKT representation of this spatial reference.

```
    .. attribute:: pretty_wkt
```

    Returns the 'pretty' representation of the WKT.

```
    .. attribute:: proj
```

    Returns the PROJ representation for this spatial reference.

```
    .. attribute:: proj4
```

    Alias for :attr:`SpatialReference.proj`.

```
    .. attribute:: xml
```

    Returns the XML representation of this spatial reference.

```
``CoordTransform``
```
```
------------------
```

.. class:: CoordTransform(source, target)

Represents a coordinate system transform. It is initialized with two

:class:`SpatialReference`, representing the source and target coordinate

systems, respectively. These objects should be used when performing the same

coordinate transformation repeatedly on different geometries::

    >>> ct = CoordTransform(SpatialReference('WGS84'), SpatialReference('NAD83'))

```
    >>> for feat in layer:
```

    ...     geom = feat.geom # getting clone of feature geometry

    ...     geom.transform(ct) # transforming

```
.. _raster-data-source-objects:
```
```
Raster Data Objects
```
```
===================
```
```
``GDALRaster``
```
```
----------------
```

:class:`GDALRaster` is a wrapper for the GDAL raster source object that

supports reading data from a variety of GDAL-supported geospatial file

formats and data sources using a consistent interface.  Each

data source is represented by a :class:`GDALRaster` object which contains

one or more layers of data named bands.  Each band, represented by a

:class:`GDALBand` object, contains georeferenced image data. For example, an RGB

image is represented as three bands: one for red, one for green, and one for

```
blue.
```
```
.. note::
```

    For raster data there is no difference between a raster instance and its

    data source. Unlike for the Geometry objects, :class:`GDALRaster` objects are

    always a data source. Temporary rasters can be instantiated in memory

    using the corresponding driver, but they will be of the same class as file-based

```
    raster sources.
```

.. class:: GDALRaster(ds_input, write=False)

    The constructor for ``GDALRaster`` accepts two parameters. The first

    parameter defines the raster source, and the second parameter defines if a

    raster should be opened in write mode. For newly-created rasters, the second

    parameter is ignored and the new raster is always created in write mode.

    The first parameter can take three forms: a string representing a file path

    (filesystem or GDAL virtual filesystem), a dictionary with values defining

    a new raster, or a bytes object representing a raster file.

    If the input is a file path, the raster is opened from there. If the input

    is raw data in a dictionary, the parameters ``width``, ``height``, and

    ``srid`` are required. If the input is a bytes object, it will be opened

```
    using a GDAL virtual filesystem.
```

    For a detailed description of how to create rasters using dictionary input,

    see :ref:`gdal-raster-ds-input`. For a detailed description of how to

    create rasters in the virtual filesystem, see :ref:`gdal-raster-vsimem`.

    The following example shows how rasters can be created from different input

    sources (using the sample data from the GeoDjango tests; see also the

```
    :ref:`gdal_sample_data` section).
```

        >>> from django.contrib.gis.gdal import GDALRaster

        >>> rst = GDALRaster('/path/to/your/raster.tif', write=False)

```
        >>> rst.name
```
```
        '/path/to/your/raster.tif'
```

        >>> rst.width, rst.height  # This file has 163 x 174 pixels

```
        (163, 174)
```

        >>> rst = GDALRaster({  # Creates an in-memory raster

```
        ...     'srid': 4326,
```
```
        ...     'width': 4,
```
```
        ...     'height': 4,
```
```
        ...     'datatype': 1,
```
```
        ...     'bands': [{
```
```
        ...         'data': (2, 3),
```
```
        ...         'offset': (1, 1),
```
```
        ...         'size': (2, 2),
```
```
        ...         'shape': (2, 1),
```
```
        ...         'nodata_value': 5,
```
```
        ...     }]
```
```
        ... })
```
```
        >>> rst.srs.srid
```
```
        4326
```
```
        >>> rst.width, rst.height
```
```
        (4, 4)
```
```
        >>> rst.bands[0].data()
```
```
        array([[5, 5, 5, 5],
```
```
               [5, 2, 3, 5],
```
```
               [5, 2, 3, 5],
```

               [5, 5, 5, 5]], dtype=uint8)

        >>> rst_file = open('/path/to/your/raster.tif', 'rb')

        >>> rst_bytes = rst_file.read()

        >>> rst = GDALRaster(rst_bytes)

```
        >>> rst.is_vsi_based
```
```
        True
```

        >>> rst.name  # Stored in a random path in the vsimem filesystem.

        '/vsimem/da300bdb-129d-49a8-b336-e410a9428dad'

```
    .. versionchanged:: 4.0
```

        Creating rasters in any GDAL virtual filesystem was allowed.

```
    .. attribute:: name
```

        The name of the source which is equivalent to the input file path or the name

```
        provided upon instantiation.
```

            >>> GDALRaster({'width': 10, 'height': 10, 'name': 'myraster', 'srid': 4326}).name

```
            'myraster'
```
```
    .. attribute:: driver
```

        The name of the GDAL driver used to handle the input file. For ``GDALRaster``\s created

        from a file, the driver type is detected automatically. The creation of rasters from

        scratch is an in-memory raster by default (``'MEM'``), but can be

        altered as needed. For instance, use ``GTiff`` for a ``GeoTiff`` file.

        For a list of file types, see also the `GDAL Raster Formats`__ list.

        __ https://gdal.org/drivers/raster/

        An in-memory raster is created through the following example:

            >>> GDALRaster({'width': 10, 'height': 10, 'srid': 4326}).driver.name

```
            'MEM'
```

        A file based GeoTiff raster is created through the following example:

```
            >>> import tempfile
```

            >>> rstfile = tempfile.NamedTemporaryFile(suffix='.tif')

            >>> rst = GDALRaster({'driver': 'GTiff', 'name': rstfile.name, 'srid': 4326,

            ...                   'width': 255, 'height': 255, 'nr_of_bands': 1})

```
            >>> rst.name
```

            '/tmp/tmp7x9H4J.tif'           # The exact filename will be different on your computer

```
            >>> rst.driver.name
```
```
            'GTiff'
```
```
    .. attribute:: width
```

        The width of the source in pixels (X-axis).

            >>> GDALRaster({'width': 10, 'height': 20, 'srid': 4326}).width

```
            10
```
```
    .. attribute:: height
```

        The height of the source in pixels (Y-axis).

            >>> GDALRaster({'width': 10, 'height': 20, 'srid': 4326}).height

```
            20
```
```
    .. attribute:: srs
```

        The spatial reference system of the raster, as a

        :class:`SpatialReference` instance. The SRS can be changed by

        setting it to an other :class:`SpatialReference` or providing any input

        that is accepted by the :class:`SpatialReference` constructor.

            >>> rst = GDALRaster({'width': 10, 'height': 20, 'srid': 4326})

```
            >>> rst.srs.srid
```
```
            4326
```
```
            >>> rst.srs = 3086
```
```
            >>> rst.srs.srid
```
```
            3086
```
```
    .. attribute:: srid
```

        The Spatial Reference System Identifier (SRID) of the raster. This

        property is a shortcut to getting or setting the SRID through the

```
        :attr:`srs` attribute.
```

            >>> rst = GDALRaster({'width': 10, 'height': 20, 'srid': 4326})

```
            >>> rst.srid
```
```
            4326
```
```
            >>> rst.srid = 3086
```
```
            >>> rst.srid
```
```
            3086
```

            >>> rst.srs.srid  # This is equivalent

```
            3086
```
```
    .. attribute:: geotransform
```

        The affine transformation matrix used to georeference the source, as a

        tuple of six coefficients which map pixel/line coordinates into

        georeferenced space using the following relationship::

            Xgeo = GT(0) + Xpixel*GT(1) + Yline*GT(2)

            Ygeo = GT(3) + Xpixel*GT(4) + Yline*GT(5)

        The same values can be retrieved by accessing the :attr:`origin`

        (indices 0 and 3), :attr:`scale` (indices 1 and 5) and :attr:`skew`

```
        (indices 2 and 4) properties.
```

        The default is ``[0.0, 1.0, 0.0, 0.0, 0.0, -1.0]``.

            >>> rst = GDALRaster({'width': 10, 'height': 20, 'srid': 4326})

```
            >>> rst.geotransform
```

            [0.0, 1.0, 0.0, 0.0, 0.0, -1.0]

```
    .. attribute:: origin
```

        Coordinates of the top left origin of the raster in the spatial

        reference system of the source, as a point object with ``x`` and ``y``

```
        members.
```

            >>> rst = GDALRaster({'width': 10, 'height': 20, 'srid': 4326})

```
            >>> rst.origin
```
```
            [0.0, 0.0]
```
```
            >>> rst.origin.x = 1
```
```
            >>> rst.origin
```
```
            [1.0, 0.0]
```
```
    .. attribute:: scale
```

        Pixel width and height used for georeferencing the raster, as a point

        object with ``x`` and ``y``  members. See :attr:`geotransform` for more

```
        information.
```

            >>> rst = GDALRaster({'width': 10, 'height': 20, 'srid': 4326})

```
            >>> rst.scale
```
```
            [1.0, -1.0]
```
```
            >>> rst.scale.x = 2
```
```
            >>> rst.scale
```
```
            [2.0, -1.0]
```
```
    .. attribute:: skew
```

        Skew coefficients used to georeference the raster, as a point object

        with ``x`` and ``y``  members. In case of north up images, these

```
        coefficients are both ``0``.
```

            >>> rst = GDALRaster({'width': 10, 'height': 20, 'srid': 4326})

```
            >>> rst.skew
```
```
            [0.0, 0.0]
```
```
            >>> rst.skew.x = 3
```
```
            >>> rst.skew
```
```
            [3.0, 0.0]
```
```
    .. attribute:: extent
```

        Extent (boundary values) of the raster source, as a 4-tuple

        ``(xmin, ymin, xmax, ymax)`` in the spatial reference system of the

```
        source.
```

            >>> rst = GDALRaster({'width': 10, 'height': 20, 'srid': 4326})

```
            >>> rst.extent
```
```
            (0.0, -20.0, 10.0, 0.0)
```
```
            >>> rst.origin.x = 100
```
```
            >>> rst.extent
```
```
            (100.0, -20.0, 110.0, 0.0)
```
```
    .. attribute:: bands
```

        List of all bands of the source, as :class:`GDALBand` instances.

            >>> rst = GDALRaster({"width": 1, "height": 2, 'srid': 4326,

            ...                   "bands": [{"data": [0, 1]}, {"data": [2, 3]}]})

```
            >>> len(rst.bands)
```
```
            2
```
```
            >>> rst.bands[1].data()
```

            array([[ 2.,  3.]], dtype=float32)

    .. method:: warp(ds_input, resampling='NearestNeighbour', max_error=0.0)

        Returns a warped version of this raster.

        The warping parameters can be specified through the ``ds_input``

        argument. The use of ``ds_input`` is analogous to the corresponding

        argument of the class constructor. It is a dictionary with the

        characteristics of the target raster. Allowed dictionary key values are

        width, height, SRID, origin, scale, skew, datatype, driver, and name

```
        (filename).
```

        By default, the warp functions keeps most parameters equal to the

        values of the original source raster, so only parameters that should be

        changed need to be specified. Note that this includes the driver, so

        for file-based rasters the warp function will create a new raster on

```
        disk.
```

        The only parameter that is set differently from the source raster is the

        name. The default value of the raster name is the name of the source

        raster appended with ``'_copy' + source_driver_name``. For file-based

        rasters it is recommended to provide the file path of the target raster.

        The resampling algorithm used for warping can be specified with the

        ``resampling`` argument. The default is ``NearestNeighbor``, and the

        other allowed values are ``Bilinear``, ``Cubic``, ``CubicSpline``,

        ``Lanczos``, ``Average``, and ``Mode``.

        The ``max_error`` argument can be used to specify the maximum error

        measured in input pixels that is allowed in approximating the

        transformation. The default is 0.0 for exact calculations.

        For users familiar with ``GDAL``, this function has a similar

        functionality to the ``gdalwarp`` command-line utility.

        For example, the warp function can be used for aggregating a raster to

        the double of its original pixel scale:

```
            >>> rst = GDALRaster({
```

            ...     "width": 6, "height": 6, "srid": 3086,

            ...     "origin": [500000, 400000],

            ...     "scale": [100, -100],

            ...     "bands": [{"data": range(36), "nodata_value": 99}]

```
            ... })
```

            >>> target = rst.warp({"scale": [200, -200], "width": 3, "height": 3})

```
            >>> target.bands[0].data()
```
```
            array([[  7.,   9.,  11.],
```
```
                   [ 19.,  21.,  23.],
```

                   [ 31.,  33.,  35.]], dtype=float32)

    .. method:: transform(srs, driver=None, name=None, resampling='NearestNeighbour', max_error=0.0)

        Transforms this raster to a different spatial reference system

        (``srs``), which may be a :class:`SpatialReference` object, or any

        other input accepted by :class:`SpatialReference` (including spatial

        reference WKT and PROJ strings, or an integer SRID).

        It calculates the bounds and scale of the current raster in the new

        spatial reference system and warps the raster using the

        :attr:`~GDALRaster.warp` function.

        By default, the driver of the source raster is used and the name of the

        raster is the original name appended with

        ``'_copy' + source_driver_name``. A different driver or name can be

        specified with the ``driver`` and ``name`` arguments.

        The default resampling algorithm is ``NearestNeighbour`` but can be

        changed using the ``resampling`` argument. The default maximum allowed

        error for resampling is 0.0 and can be changed using the ``max_error``

        argument. Consult the :attr:`~GDALRaster.warp` documentation for detail

```
        on those arguments.
```
```
            >>> rst = GDALRaster({
```

            ...     "width": 6, "height": 6, "srid": 3086,

            ...     "origin": [500000, 400000],

            ...     "scale": [100, -100],

            ...     "bands": [{"data": range(36), "nodata_value": 99}]

```
            ... })
```

            >>> target_srs = SpatialReference(4326)

            >>> target = rst.transform(target_srs)

```
            >>> target.origin
```

            [-82.98492744885776, 27.601924753080144]

```
    .. attribute:: info
```

        Returns a string with a summary of the raster. This is equivalent to

        the `gdalinfo`__ command line utility.

        __ https://gdal.org/programs/gdalinfo.html

```
    .. attribute:: metadata
```

        The metadata of this raster, represented as a nested dictionary. The

        first-level key is the metadata domain. The second-level contains the

        metadata item names and values from each domain.

        To set or update a metadata item, pass the corresponding metadata item

        to the method using the nested structure described above. Only keys

        that are in the specified dictionary are updated; the rest of the

```
        metadata remains unchanged.
```

        To remove a metadata item, use ``None`` as the metadata value.

            >>> rst = GDALRaster({'width': 10, 'height': 20, 'srid': 4326})

```
            >>> rst.metadata
```
```
            {}
```

            >>> rst.metadata = {'DEFAULT': {'OWNER': 'Django', 'VERSION': '1.0'}}

```
            >>> rst.metadata
```

            {'DEFAULT': {'OWNER': 'Django', 'VERSION': '1.0'}}

            >>> rst.metadata = {'DEFAULT': {'OWNER': None, 'VERSION': '2.0'}}

```
            >>> rst.metadata
```

            {'DEFAULT': {'VERSION': '2.0'}}

```
    .. attribute:: vsi_buffer
```

        A ``bytes`` representation of this raster. Returns ``None`` for rasters

        that are not stored in GDAL's virtual filesystem.

```
    .. attribute:: is_vsi_based
```

        A boolean indicating if this raster is stored in GDAL's virtual

```
        filesystem.
```
```
``GDALBand``
```
```
------------
```
```
.. class:: GDALBand
```

    ``GDALBand`` instances are not created explicitly, but rather obtained

    from a :class:`GDALRaster` object, through its :attr:`~GDALRaster.bands`

    attribute. The GDALBands contain the actual pixel values of the raster.

```
    .. attribute:: description
```

        The name or description of the band, if any.

```
    .. attribute:: width
```

        The width of the band in pixels (X-axis).

```
    .. attribute:: height
```

        The height of the band in pixels (Y-axis).

```
    .. attribute:: pixel_count
```

        The total number of pixels in this band. Is equal to ``width * height``.

    .. method:: statistics(refresh=False, approximate=False)

        Compute statistics on the pixel values of this band. The return value

        is a tuple with the following structure:

        ``(minimum, maximum, mean, standard deviation)``.

        If the ``approximate`` argument is set to ``True``, the statistics may

        be computed based on overviews or a subset of image tiles.

        If the ``refresh`` argument is set to ``True``, the statistics will be

        computed from the data directly, and the cache will be updated with the

```
        result.
```

        If a persistent cache value is found, that value is returned. For

        raster formats using Persistent Auxiliary Metadata (PAM) services, the

        statistics might be cached in an auxiliary file. In some cases this

        metadata might be out of sync with the pixel values or cause values

        from a previous call to be returned which don't reflect the value of

        the ``approximate`` argument. In such cases, use the ``refresh``

        argument to get updated values and store them in the cache.

        For empty bands (where all pixel values are "no data"), all statistics

```
        are returned as ``None``.
```

        The statistics can also be retrieved directly by accessing the

        :attr:`min`, :attr:`max`, :attr:`mean`, and :attr:`std` properties.

```
    .. attribute:: min
```

        The minimum pixel value of the band (excluding the "no data" value).

```
    .. attribute:: max
```

        The maximum pixel value of the band (excluding the "no data" value).

```
    .. attribute:: mean
```

        The mean of all pixel values of the band (excluding the "no data"

```
        value).
```
```
    .. attribute:: std
```

        The standard deviation of all pixel values of the band (excluding the

```
        "no data" value).
```
```
    .. attribute:: nodata_value
```

        The "no data" value for a band is generally a special marker value used

        to mark pixels that are not valid data. Such pixels should generally not

        be displayed, nor contribute to analysis operations.

        To delete an existing "no data" value, set this property to ``None``.

    .. method:: datatype(as_string=False)

        The data type contained in the band, as an integer constant between 0

        (Unknown) and 11. If ``as_string`` is ``True``, the data type is

        returned as a string with the following possible values:

        ``GDT_Unknown``, ``GDT_Byte``, ``GDT_UInt16``, ``GDT_Int16``,

        ``GDT_UInt32``, ``GDT_Int32``, ``GDT_Float32``, ``GDT_Float64``,

        ``GDT_CInt16``, ``GDT_CInt32``, ``GDT_CFloat32``, and ``GDT_CFloat64``.

    .. method:: color_interp(as_string=False)

        The color interpretation for the band, as an integer between 0and 16.

        If ``as_string`` is ``True``, the data type is returned as a string

        with the following possible values:

        ``GCI_Undefined``, ``GCI_GrayIndex``, ``GCI_PaletteIndex``,

        ``GCI_RedBand``, ``GCI_GreenBand``, ``GCI_BlueBand``, ``GCI_AlphaBand``,

        ``GCI_HueBand``, ``GCI_SaturationBand``, ``GCI_LightnessBand``,

        ``GCI_CyanBand``, ``GCI_MagentaBand``, ``GCI_YellowBand``,

        ``GCI_BlackBand``, ``GCI_YCbCr_YBand``, ``GCI_YCbCr_CbBand``, and

        ``GCI_YCbCr_CrBand``. ``GCI_YCbCr_CrBand`` also represents ``GCI_Max``

        because both correspond to the integer 16, but only ``GCI_YCbCr_CrBand``

```
        is returned as a string.
```

    .. method:: data(data=None, offset=None, size=None, shape=None)

        The accessor to the pixel values of the ``GDALBand``. Returns the complete

        data array if no parameters are provided. A subset of the pixel array can

        be requested by specifying an offset and block size as tuples.

        If NumPy is available, the data is returned as NumPy array. For performance

        reasons, it is highly recommended to use NumPy.

        Data is written to the ``GDALBand`` if the ``data`` parameter is provided.

        The input can be of one of the following types - packed string, buffer, list,

        array, and NumPy array. The number of items in the input should normally

        correspond to the total number of pixels in the band, or to the number

        of pixels for a specific block of pixel values if the ``offset`` and

        ``size`` parameters are provided.

        If the number of items in the input is different from the target pixel

        block, the ``shape`` parameter must be specified. The shape is a tuple

        that specifies the width and height of the input data in pixels. The

        data is then replicated to update the pixel values of the selected

        block. This is useful to fill an entire band with a single value, for

```
        instance.
```
```
        For example:
```

            >>> rst = GDALRaster({'width': 4, 'height': 4, 'srid': 4326, 'datatype': 1, 'nr_of_bands': 1})

```
            >>> bnd = rst.bands[0]
```
```
            >>> bnd.data(range(16))
```
```
            >>> bnd.data()
```
```
            array([[ 0,  1,  2,  3],
```
```
                   [ 4,  5,  6,  7],
```
```
                   [ 8,  9, 10, 11],
```

                   [12, 13, 14, 15]], dtype=int8)

            >>> bnd.data(offset=(1, 1), size=(2, 2))

```
            array([[ 5,  6],
```

                   [ 9, 10]], dtype=int8)

            >>> bnd.data(data=[-1, -2, -3, -4], offset=(1, 1), size=(2, 2))

```
            >>> bnd.data()
```
```
            array([[ 0,  1,  2,  3],
```
```
                   [ 4, -1, -2,  7],
```
```
                   [ 8, -3, -4, 11],
```

                   [12, 13, 14, 15]], dtype=int8)

            >>> bnd.data(data='\x9d\xa8\xb3\xbe', offset=(1, 1), size=(2, 2))

```
            >>> bnd.data()
```

            array([[  0,   1,   2,   3],

                   [  4, -99, -88,   7],

                   [  8, -77, -66,  11],

                   [ 12,  13,  14,  15]], dtype=int8)

            >>> bnd.data([1], shape=(1, 1))

```
            >>> bnd.data()
```
```
            array([[1, 1, 1, 1],
```
```
                   [1, 1, 1, 1],
```
```
                   [1, 1, 1, 1],
```

                   [1, 1, 1, 1]], dtype=uint8)

            >>> bnd.data(range(4), shape=(1, 4))

```
            array([[0, 0, 0, 0],
```
```
                   [1, 1, 1, 1],
```
```
                   [2, 2, 2, 2],
```

                   [3, 3, 3, 3]], dtype=uint8)

```
    .. attribute:: metadata
```

        The metadata of this band. The functionality is identical to

```
        :attr:`GDALRaster.metadata`.
```
```
.. _gdal-raster-ds-input:
```
```
Creating rasters from data
```
```
--------------------------
```

This section describes how to create rasters from scratch using the

```
``ds_input`` parameter.
```

A new raster is created when a ``dict`` is passed to the :class:`GDALRaster`

constructor. The dictionary contains defining parameters of the new raster,

such as the origin, size, or spatial reference system. The dictionary can also

contain pixel data and information about the format of the new raster. The

resulting raster can therefore be file-based or memory-based, depending on the

```
driver specified.
```

There's no standard for describing raster data in a dictionary or JSON flavor.

The definition of the dictionary input to the :class:`GDALRaster` class is

therefore specific to Django. It's inspired by the `geojson`__ format, but the

``geojson`` standard is currently limited to vector formats.

Examples of using the different keys when creating rasters can be found in the

documentation of the corresponding attributes and methods of the

:class:`GDALRaster` and :class:`GDALBand` classes.

```
__ https://geojson.org/
```
```
The ``ds_input`` dictionary
```
```
~~~~~~~~~~~~~~~~~~~~~~~~~~~
```

Only a few keys are required in the ``ds_input`` dictionary to create a raster:

``width``, ``height``, and ``srid``. All other parameters have default values

(see the table below). The list of keys that can be passed in the ``ds_input``

dictionary is closely related but not identical to the :class:`GDALRaster`

properties. Many of the parameters are mapped directly to those properties;

```
the others are described below.
```

The following table describes all keys that can be set in the ``ds_input``

```
dictionary.
```

================= ======== ==================================================

```
Key               Default  Usage
```

================= ======== ==================================================

``srid``          required Mapped to the :attr:`~GDALRaster.srid` attribute

``width``         required Mapped to the :attr:`~GDALRaster.width` attribute

``height``        required Mapped to the :attr:`~GDALRaster.height` attribute

``driver``        ``MEM``  Mapped to the :attr:`~GDALRaster.driver` attribute

```
``name``          ``''``   See below
```

``origin``        ``0``    Mapped to the :attr:`~GDALRaster.origin` attribute

``scale``         ``0``    Mapped to the :attr:`~GDALRaster.scale` attribute

``skew``          ``0``    Mapped to the :attr:`~GDALRaster.width` attribute

```
``bands``         ``[]``   See below
```
```
``nr_of_bands``   ``0``    See below
```
```
``datatype``      ``6``    See below
```
```
``papsz_options`` ``{}``   See below
```

================= ======== ==================================================

```
.. object:: name
```

    String representing the name of the raster. When creating a file-based

    raster, this parameter must be the file path for the new raster. If the

    name starts with ``/vsimem/``, the raster is created in GDAL's virtual

```
    filesystem.
```
```
.. object:: datatype
```

    Integer representing the data type for all the bands. Defaults to ``6``

    (Float32). All bands of a new raster are required to have the same datatype.

```
    The value mapping is:
```

    ===== =============== ===============================

```
    Value GDAL Pixel Type Description
```

    ===== =============== ===============================

    1     GDT_Byte        Eight bit unsigned integer

    2     GDT_UInt16      Sixteen bit unsigned integer

    3     GDT_Int16       Sixteen bit signed integer

    4     GDT_UInt32      Thirty-two bit unsigned integer

    5     GDT_Int32       Thirty-two bit signed integer

    6     GDT_Float32     Thirty-two bit floating point

    7     GDT_Float64     Sixty-four bit floating point

    ===== =============== ===============================

```
.. object:: nr_of_bands
```

    Integer representing the number of bands of the raster. A raster can be

    created without passing band data upon creation. If the number of bands

    isn't specified, it's automatically calculated from the length of the

    ``bands`` input. The number of bands can't be changed after creation.

```
.. object:: bands
```

    A list of ``band_input`` dictionaries with band input data. The resulting

    band indices are the same as in the list provided. The definition of the

    band input dictionary is given below. If band data isn't provided, the

    raster bands values are instantiated as an array of zeros and the "no

```
    data" value is set to ``None``.
```
```
.. object:: papsz_options
```

    A dictionary with raster creation options. The key-value pairs of the

    input dictionary are passed to the driver on creation of the raster.

    The available options are driver-specific and are described in the

```
    documentation of each driver.
```

    The values in the dictionary are not case-sensitive and are automatically

    converted to the correct string format upon creation.

    The following example uses some of the options available for the

    `GTiff driver`__. The result is a compressed signed byte raster with an

    internal tiling scheme. The internal tiles have a block size of 23 by 23::

```
        >>> GDALRaster({
```
```
        ...    'driver': 'GTiff',
```

        ...    'name': '/path/to/new/file.tif',

```
        ...    'srid': 4326,
```
```
        ...    'width': 255,
```
```
        ...    'height': 255,
```
```
        ...    'nr_of_bands': 1,
```
```
        ...    'papsz_options': {
```

        ...        'compress': 'packbits',

        ...        'pixeltype': 'signedbyte',

```
        ...        'tiled': 'yes',
```
```
        ...        'blockxsize': 23,
```
```
        ...        'blockysize': 23,
```
```
        ...    }
```
```
        ... })
```

__ https://gdal.org/drivers/raster/gtiff.html

```
The ``band_input`` dictionary
```
```
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
```

The ``bands`` key in the ``ds_input`` dictionary is a list of ``band_input``

dictionaries. Each ``band_input`` dictionary can contain pixel values and the

"no data" value to be set on the bands of the new raster. The data array can

have the full size of the new raster or be smaller. For arrays that are smaller

than the full raster, the ``size``, ``shape``, and ``offset`` keys  control the

pixel values. The corresponding keys are passed to the :meth:`~GDALBand.data`

method. Their functionality is the same as setting the band data with that

method. The following table describes the keys that can be used.

================ ================================= ======================================================

Key              Default                           Usage

================ ================================= ======================================================

``nodata_value`` ``None``                          Mapped to the :attr:`~GDALBand.nodata_value` attribute

``data``         Same as ``nodata_value`` or ``0`` Passed to the :meth:`~GDALBand.data` method

``size``         ``(with, height)`` of raster      Passed to the :meth:`~GDALBand.data` method

``shape``        Same as size                      Passed to the :meth:`~GDALBand.data` method

``offset``       ``(0, 0)``                        Passed to the :meth:`~GDALBand.data` method

================ ================================= ======================================================

```
.. _gdal-raster-vsimem:
```
```
Using GDAL's Virtual Filesystem
```
```
-------------------------------
```

GDAL can access files stored in the filesystem, but also supports virtual

filesystems to abstract accessing other kind of files, such as compressed,

```
encrypted, or remote files.
```
```
Using memory-based Virtual Filesystem
```
```
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
```

GDAL has an internal memory-based filesystem, which allows treating blocks of

memory as files. It can be used to read and write :class:`GDALRaster` objects

```
to and from binary file buffers.
```

This is useful in web contexts where rasters might be obtained as a buffer

from a remote storage or returned from a view without being written to disk.

:class:`GDALRaster` objects are created in the virtual filesystem when a

``bytes`` object is provided as input, or when the file path starts with

```
``/vsimem/``.
```

Input provided as ``bytes`` has to be a full binary representation of a file.

```
For instance::
```

    # Read a raster as a file object from a remote source.

    >>> from urllib.request import urlopen

    >>> dat = urlopen('http://example.com/raster.tif').read()

    # Instantiate a raster from the bytes object.

```
    >>> rst = GDALRaster(dat)
```

    # The name starts with /vsimem/, indicating that the raster lives in the

```
    # virtual filesystem.
```
```
    >>> rst.name
```

    '/vsimem/da300bdb-129d-49a8-b336-e410a9428dad'

To create a new virtual file-based raster from scratch, use the ``ds_input``

dictionary representation and provide a ``name`` argument that starts with

``/vsimem/`` (for detail of the dictionary representation, see

:ref:`gdal-raster-ds-input`). For virtual file-based rasters, the

:attr:`~GDALRaster.vsi_buffer` attribute returns the ``bytes`` representation

```
of the raster.
```

Here's how to create a raster and return it as a file in an

```
:class:`~django.http.HttpResponse`::
```

    >>> from django.http import HttpResponse

```
    >>> rst = GDALRaster({
```

    ...     'name': '/vsimem/temporarymemfile',

```
    ...     'driver': 'tif',
```

    ...     'width': 6, 'height': 6, 'srid': 3086,

    ...     'origin': [500000, 400000],

```
    ...     'scale': [100, -100],
```

    ...     'bands': [{'data': range(36), 'nodata_value': 99}]

```
    ... })
```

    >>> HttpResponse(rast.vsi_buffer, 'image/tiff')

```
Using other Virtual Filesystems
```
```
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
```
```
.. versionadded:: 4.0
```

Depending on the local build of GDAL other virtual filesystems may be

supported. You can use them by prepending the provided path with the

appropriate ``/vsi*/`` prefix. See the `GDAL Virtual Filesystems

```
documentation`_ for more details.
```
```
.. warning:
```

    Rasters with names starting with `/vsi*/` will be treated as rasters from

    the GDAL virtual filesystems. Django doesn't perform any extra validation.

```
Compressed rasters
```
```
^^^^^^^^^^^^^^^^^^
```

Instead decompressing the file and instantiating the resulting raster, GDAL can

directly access compressed files using the ``/vsizip/``, ``/vsigzip/``, or

```
``/vsitar/`` virtual filesystems::
```

   >>> from django.contrib.gis.gdal import GDALRaster

   >>> rst = GDALRaster('/vsizip/path/to/your/file.zip/path/to/raster.tif')

   >>> rst = GDALRaster('/vsigzip/path/to/your/file.gz')

   >>> rst = GDALRaster('/vsitar/path/to/your/file.tar/path/to/raster.tif')

```
Network rasters
```
```
^^^^^^^^^^^^^^^
```

GDAL can support online resources and storage providers transparently. As long

```
as it's built with such capabilities.
```

To access a public raster file with no authentication, you can use

```
``/vsicurl/``::
```

   >>> from django.contrib.gis.gdal import GDALRaster

   >>> rst = GDALRaster('/vsicurl/https://example.com/raster.tif')

```
   >>> rst.name
```

   '/vsicurl/https://example.com/raster.tif'

For commercial storage providers (e.g. ``/vsis3/``) the system should be

previously configured for authentication and possibly other settings (see the

`GDAL Virtual Filesystems documentation`_ for available options).

.. _`GDAL Virtual Filesystems documentation`: https://gdal.org/user/virtual_file_systems.html

```
Settings
```
```
========
```
```
.. setting:: GDAL_LIBRARY_PATH
```
```
``GDAL_LIBRARY_PATH``
```
```
---------------------
```

A string specifying the location of the GDAL library.  Typically,

this setting is only used if the GDAL library is in a non-standard

location (e.g., ``/home/john/lib/libgdal.so``).

```
Exceptions
```
```
==========
```
```
.. exception:: GDALException
```

    The base GDAL exception, indicating a GDAL-related error.

```
.. exception:: SRSException
```

    An exception raised when an error occurs when constructing or using a

```
    spatial reference system object.
```