|Mathematica Import/Export Format|
|SDTS GIS format.|
Geographic information standard used by the U.S. Geological Survey.
Used for archiving and exchanging maps and map data.
SDTS is an acronym for Spatial Data Transfer Standard.
Based on ISO 8211.
U.S. Federal Information Processing Standard.
An SDTS transfer archive consists of multiple .ddf files combined in a .tar.gz file.
The file extension .ddf is derived from Data Descriptive File.
Contains digital line graphs (DLG) or digital elevation models (DEM).
Digital line graphs are vector data commonly used for maps.
Digital elevation models are stored as a raster of elevation values.
|"Elements"||list of elements and options available in this file|
|"Rules"||full list of rules for each element and option|
|"Options"||list of rules for options, properties and settings|
|"Graphics"||all layers combined into a single Graphics object|
|"GraphicsList"||list of graphics representing the layers of an SDTS archive|
|"Data"||graphics primitives for each layer|
|"ElevationRange"||range of elevation coordinates, typically given in meters|
|"SpatialRange"||range of geographic coordinates, typically given in decimal degrees|
|DataRange||Automatic||the range of latitude and longitude values to assume for the data|
|ImageSize||Automatic||overall size of the image|
|BoxRatios||Automatic||effective 3D bounding box ratios|
|ColorFunction||"Topographic"||how to determine the color of surfaces|
|DataReversed||False||whether to reverse the order of rows|
|LightingAngle||Automatic||the effective angle from which simulated illumination is taken to come|
|"DefaultElevation"||0||elevation setting for areas not covered by the file|
|"DownsamplingFactor"||1||integer factor by which the amount of DEM data in each horizontal dimension is reduced on import|
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