ArcGRID

Background & Context

    • ArcGRID topographic data format.
    • Standard distribution format of USGS National Map data.
    • Stores terrain data.
    • Bundle format, consisting of binary .adf and other files.
    • Developed by ESRI.

Import

  • Import["dir","ArcGRID"] or Import["dir"] imports an ArcGRID directory bundle and returns a combined rendering of the data.
  • Import["dir"] returns a Graphics object.
  • Import["dir","elem"] imports the specified element from an ArcGRID file.
  • Import["dir",{{"elem1","elem2",…}}] imports multiple elements.
  • See the following reference pages for full general information:
  • Importimport from a file
    CloudImportimport from a cloud object
    ImportStringimport from a string
    ImportByteArrayimport from a byte array

Import Elements

  • General Import elements:
  • "Elements"list of elements and options available in this file
    "Summary"summary of the file
    "Rules"list of rules for all available elements
  • Data representation elements:
  • "Data"array of terrain elevation values
    "Graphics"DEM file rendered as ReliefPlot
    "Image"raw DEM data as an image object
    "ReliefImage"DEM file rendered as ReliefImage
  • Import by default uses the "Graphics" element for the ArcGRID format.
  • Metadata elements:
  • "DataFormat"type used to represent elevation values
    "ElevationRange"range of elevation values
    "RasterSize"size of the terrain grid
    "SpatialRange"range of geographic coordinates, given in coordinate system units
    "SpatialResolution"grid spacing in coordinate system units
  • Import["dir","ElevationRange"] gives the range {zmin,zmax} of elevation values in units of meters.
  • Import["dir","SpatialRange"] gives the bounding coordinates of the geographic region covered by the file as an expression of the form {{latmin,latmax},{longmin,longmax}}.
  • Elements representing the geodetic datum and reference ellipsoid used in the file:
  • "CoordinateSystem"name of the coordinate system used in the file
    "Datum"geodetic datum
    "SemimajorAxis"semimajor axis of the reference ellipsoid in meters
    "SemiminorAxis"semiminor axis of the reference ellipsoid in meters
    "InverseFlattening"inverse flattening of the ellipsoid
    "LinearUnits"coordinate system units
  • Elements specifying the cartographic projection and its parameters:
  • "Projection"projection name and parameters
    "Centering"latitude and longitude defining the origin of the projection
    "StandardParallels"standard parallels
    "CentralScaleFactor"scale factor at the central meridian or center of projection
    "GridOrigin"grid coordinates {n,e} of the central parallel and meridian
    "ProjectionName"Wolfram Language standard name of the projection used
    "ReferenceModel"what reference sphere or ellipsoid to use
  • Accessing low-level meta-information from the file:
  • "CoordinateSystemInformation"raw parameters of the coordinate system as stored in the file
  • See the reference page for GeoProjectionData for full information on cartographic projections.

Options

  • General rendering options:
  • BackgroundNonebackground color
    DataRangeAutomaticthe range of latitude and longitude values to assume for the data
    ImageSizeAutomaticoverall size of the image
  • DEM rendering options:
  • BoxRatiosAutomaticeffective 3D bounding box ratios
    ColorFunction"Topographic"how to determine the color of surfaces
    DataReversedFalsewhether to reverse the order of rows
    LightingAngleAutomaticthe effective angle from which simulated illumination is taken to come
  • Import options:
  • "DefaultElevation"Automaticelevation setting for areas not covered by the file
    "DownsamplingFactor"1integer factor by which the amount of DEM data in each horizontal dimension is reduced on import

Examples

Basic Examples  (3)

Import an ArcGRID digital elevation model:

Get the names of the Import elements available in this file:

Show the names of files contained in this ArcGRID bundle:

Generate a histogram of elevation values from the file: