Raster Object Base

The RasterObject provides common methods for generating visualizations for raster type files. All objects that contain rasters inherit from this base class.

class gsshapy.base.RasterObjectBase[source]

Abstract base class for raster objects.

getAsKmlGrid(session, path=None, documentName=None, colorRamp=0, alpha=1.0, noDataValue=None)[source]

Retrieve the raster as a KML document with each cell of the raster represented as a vector polygon. The result is a vector grid of raster cells. Cells with the no data value are excluded.

Parameters:
  • session (sqlalchemy.orm.session.Session) – SQLAlchemy session object bound to PostGIS enabled database.
  • path (str, optional) – Path to file where KML file will be written. Defaults to None.
  • documentName (str, optional) – Name of the KML document. This will be the name that appears in the legend. Defaults to ‘Stream Network’.
  • colorRamp (mapkit.ColorRampGenerator.ColorRampEnum or dict, optional) – Use ColorRampEnum to select a default color ramp or a dictionary with keys ‘colors’ and ‘interpolatedPoints’ to specify a custom color ramp. The ‘colors’ key must be a list of RGB integer tuples (e.g.: (255, 0, 0)) and the ‘interpolatedPoints’ must be an integer representing the number of points to interpolate between each color given in the colors list.
  • alpha (float, optional) – Set transparency of visualization. Value between 0.0 and 1.0 where 1.0 is 100% opaque and 0.0 is 100% transparent. Defaults to 1.0.
  • noDataValue (float, optional) – The value to treat as no data when generating visualizations of rasters. Defaults to 0.0.
Returns:

KML string
Return type:

str
getAsKmlClusters(session, path=None, documentName=None, colorRamp=0, alpha=1.0, noDataValue=None)[source]

Retrieve the raster as a KML document with adjacent cells with the same value aggregated into vector polygons. The result is a vector representation cells clustered together. Cells with the no data value are excluded.

Parameters:
  • session (sqlalchemy.orm.session.Session) – SQLAlchemy session object bound to PostGIS enabled database.
  • path (str, optional) – Path to file where KML file will be written. Defaults to None.
  • documentName (str, optional) – Name of the KML document. This will be the name that appears in the legend. Defaults to ‘Stream Network’.
  • colorRamp (mapkit.ColorRampGenerator.ColorRampEnum or dict, optional) – Use ColorRampEnum to select a default color ramp or a dictionary with keys ‘colors’ and ‘interpolatedPoints’ to specify a custom color ramp. The ‘colors’ key must be a list of RGB integer tuples (e.g.: (255, 0, 0)) and the ‘interpolatedPoints’ must be an integer representing the number of points to interpolate between each color given in the colors list.
  • alpha (float, optional) – Set transparency of visualization. Value between 0.0 and 1.0 where 1.0 is 100% opaque and 0.0 is 100% transparent. Defaults to 1.0.
  • noDataValue (float, optional) – The value to treat as no data when generating visualizations of rasters. Defaults to 0.0.
Returns:

KML string
Return type:

str
getAsKmlPng(session, path=None, documentName=None, colorRamp=0, alpha=1.0, noDataValue=None, drawOrder=0, cellSize=None, resampleMethod='NearestNeighbour')[source]

Retrieve the raster as a PNG image ground overlay KML format. Coarse grid resolutions must be resampled to smaller cell/pixel sizes to avoid a “fuzzy” look. Cells with the no data value are excluded.

Parameters:
  • session (sqlalchemy.orm.session.Session) – SQLAlchemy session object bound to PostGIS enabled database.
  • path (str, optional) – Path to file where KML file will be written. Defaults to None.
  • documentName (str, optional) – Name of the KML document. This will be the name that appears in the legend. Defaults to ‘Stream Network’.
  • colorRamp (mapkit.ColorRampGenerator.ColorRampEnum or dict, optional) – Use ColorRampEnum to select a default color ramp or a dictionary with keys ‘colors’ and ‘interpolatedPoints’ to specify a custom color ramp. The ‘colors’ key must be a list of RGB integer tuples (e.g.: (255, 0, 0)) and the ‘interpolatedPoints’ must be an integer representing the number of points to interpolate between each color given in the colors list.
  • alpha (float, optional) – Set transparency of visualization. Value between 0.0 and 1.0 where 1.0 is 100% opaque and 0.0 is 100% transparent. Defaults to 1.0.
  • noDataValue (float, optional) – The value to treat as no data when generating visualizations of rasters. Defaults to 0.0.
  • drawOrder (int, optional) – Set the draw order of the images. Defaults to 0.
  • cellSize (float, optional) – Define the cell size in the units of the project projection at which to resample the raster to generate the PNG. Defaults to None which will cause the PNG to be generated with the original raster cell size. It is generally better to set this to a size smaller than the original cell size to obtain a higher resolution image. However, computation time increases exponentially as the cell size is decreased.
  • resampleMethod (str, optional) – If cellSize is set, this method will be used to resample the raster. Valid values include: NearestNeighbour, Bilinear, Cubic, CubicSpline, and Lanczos. Defaults to NearestNeighbour.
Returns:

Returns a KML string and a list of binary strings that are the PNG images.
Return type:

(str, list)
getAsGrassAsciiGrid(session)[source]

Retrieve the raster in the GRASS ASCII Grid format.

Parameters:session (sqlalchemy.orm.session.Session) – SQLAlchemy session object bound to PostGIS enabled database.
Returns:GRASS ASCII string.
Return type:str