UsgsDigitalElevationModel Class |
A terrain provider for reading terrain from USGS Digital Elevation Model (DEM) files.
Inheritance HierarchySystemObject
AGI.Foundation.TerrainTerrainProvider
AGI.Foundation.TerrainRasterTerrainProvider
AGI.Foundation.TerrainUsgsDigitalElevationModel
AGI.Foundation.TerrainTerrainProvider
AGI.Foundation.TerrainRasterTerrainProvider
AGI.Foundation.TerrainUsgsDigitalElevationModel
Namespace: AGI.Foundation.Terrain
Assembly: AGI.Foundation.TerrainReaders (in AGI.Foundation.TerrainReaders.dll) Version: 24.2.419.0 (24.2.419.0)
SyntaxThe UsgsDigitalElevationModel type exposes the following members.
Constructors| Name | Description | |
|---|---|---|
 | UsgsDigitalElevationModel(StreamFactory) |
Initializes a new instance with the specified stream factory.
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| UsgsDigitalElevationModel(String) |
Initializes a new instance using the specified DEM filename.
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| UsgsDigitalElevationModel(StreamFactory, TerrainCacheGroup) |
Initializes a new instance with the specified stream factory.
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| UsgsDigitalElevationModel(String, TerrainCacheGroup) |
Initializes a new instance using the specified DEM filename.
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Properties| Name | Description | |
|---|---|---|
 | BoundingExtent |
Gets or sets the smallest rectangular extent that bounds the terrain provided by this terrain provider.
The returned extent's edges are expressed in radians.
(Inherited from TerrainProvider.) |
| BoundingExtentNativeUnits |
Gets or sets the smallest rectangular extent that bounds the terrain provided by this terrain provider.
The returned extent's edges are expressed in the native units of the terrain provider.
(Inherited from TerrainProvider.) |
| Cache |
Gets the cache for this terrain provider.
(Inherited from RasterTerrainProvider.) |
| DefaultInterpolator |
Gets or sets the default interpolator to use to interpolate heights
when a specific interpolator is not specified in the call to GetHeight(Double, Double)
or GetHeightNativeUnits(Double, Double).
(Inherited from RasterTerrainProvider.) |
| DeltaLatitude |
Gets or sets the distance between each post in the latitude direction, in radians.
(Inherited from RasterTerrainProvider.) |
| DeltaLatitudeNativeUnits |
Gets or sets the distance between each post in the latitude direction, in the native units of the provider.
(Inherited from RasterTerrainProvider.) |
| DeltaLongitude |
Gets or sets the distance between each post in the longitude direction, in radians.
(Inherited from RasterTerrainProvider.) |
| DeltaLongitudeNativeUnits |
Gets or sets the distance between each post in the longitude direction, in the native units of the provider.
(Inherited from RasterTerrainProvider.) |
| EasternPostOffsetNativeUnits |
Gets or sets the longitude offset (from the east) of the eastern-most post in the terrain provider.
(Inherited from RasterTerrainProvider.) |
| HeightReference |
Gets or sets an enumeration indicating whether the heights returned by the GetHeight(Double, Double) method
are relative to the Shape or to the ReferenceSurface.
(Inherited from TerrainProvider.) |
| LatitudePosts |
Gets or sets the number of posts in the latitude direction.
(Inherited from RasterTerrainProvider.) |
| LongitudePosts |
Gets or sets the number of posts in the longitude direction.
(Inherited from RasterTerrainProvider.) |
| MinimumSampleSpacing |
Gets the smallest distance between the successive height samples of the terrain data, in radians.
If the return value is 0.0, then the minimum sample spacing is unknown.
(Inherited from RasterTerrainProvider.) |
| NativeToMeters |
Gets or sets the value to multiply a height in the native units of the terrain provider
to convert it to meters.
(Inherited from TerrainProvider.) |
 | NeedsSpecialCoordinateProcessing |
Gets or sets a value indicating whether or not special processing of longitude and latitude coordinates
is required by this terrain provider. If this value is ,
GetHeightNativeUnits(Double, Double, RasterTerrainInterpolator) will call ProcessCoordinates(Double, Double)
before using the coordinates to load sets of posts or interpolate heights.
(Inherited from RasterTerrainProvider.) |
| NorthernPostOffsetNativeUnits |
Gets or sets the latitude offset (from the north) of the northern-most post in the terrain provider.
(Inherited from RasterTerrainProvider.) |
| RadiansToNative |
Gets or sets the value to multiply an angle in radians by in order to convert it to the
internal units of the terrain provider.
(Inherited from TerrainProvider.) |
| ReferenceSurface |
Gets or sets the reference surface.
The GetHeight(Double, Double) method returns heights relative to this reference surface.
If this property is , the heights are relative to the surface of the Shape ellipsoid instead.
(Inherited from TerrainProvider.) |
| Shape |
Gets or sets the shape on which the longitude and latitude are defined.
If ReferenceSurface is ,
the heights returned by GetHeight(Double, Double) are relative to this ellipsoid as well.
(Inherited from TerrainProvider.) |
| ShapeFixedFrame |
Gets or sets the reference frame fixed to the Shape in which the
longitude and latitude are defined.
(Inherited from TerrainProvider.) |
| SouthernPostOffsetNativeUnits |
Gets or sets the latitude offset (toward the north) of the southern-most post in the terrain provider.
(Inherited from RasterTerrainProvider.) |
| WesternPostOffsetNativeUnits |
Gets or sets the longitude offset (toward the east) of the western-most post in the terrain provider.
(Inherited from RasterTerrainProvider.) |
Methods| Name | Description | |
|---|---|---|
| CartographicExtentToIndexExtent |
Gets the post indices corresponding to a given cartographic extent.
(Inherited from RasterTerrainProvider.) |
| Equals | Determines whether the specified object is equal to the current object. (Inherited from Object.) |
 | Finalize | Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.) |
| GetFirstPartials(Double, Double) |
Get the partial derivatives of height with respect to the specified longitude and
latitude relative to the provider's Shape.
(Inherited from RasterTerrainProvider.) |
| GetFirstPartials(Double, Double, RasterTerrainInterpolator) |
Get the interpolated partial derivatives of height with respect to the specified longitude and
latitude relative to the provider's Shape.
(Inherited from RasterTerrainProvider.) |
| GetGradient | Get the interpolated gradient of height with respect to the terrain at the specified longitude and latitude relative to the provider's Shape. This method produces a vector representing the gradient of height in the ShapeFixedFrame. Note: The direction for the gradient is defined for use as the outward facing surface normal direction. To obtain the directional derivative for the height (rate of change of height with respect to time), take the negative gradient and dot it with a unit vector along the desired azimuth (change in height with respect to distance), times the speed along that direction in meters/second. The gradient, as defined above, is parallel to the upward facing terrain surface normal, but its magnitude indicates the rate of change in the height at that location. |
| GetHashCode | Serves as the default hash function. (Inherited from Object.) |
| GetHeight(Double, Double) |
Gets the interpolated height of the terrain at the specified longitude and latitude using the
default interpolator for this terrain provider.
(Inherited from RasterTerrainProvider.) |
| GetHeight(Double, Double, RasterTerrainInterpolator) |
Gets the interpolated height of the terrain at the specified longitude and latitude using the
specified TerrainInterpolatorTData.
(Inherited from RasterTerrainProvider.) |
| GetHeightNativeUnits(Double, Double) |
Gets the interpolated height of the terrain at the specified longitude and latitude.
(Inherited from RasterTerrainProvider.) |
| GetHeightNativeUnits(Double, Double, RasterTerrainInterpolator) |
Gets the interpolated height of the terrain at the specified longitude and latitude.
(Inherited from RasterTerrainProvider.) |
| GetHeightRelativeToShape(Double, Double) |
Gets the interpolated height of the terrain at the specified longitude and latitude
relative to the provider's Shape.
This method takes into account the heights of any reference surfaces.
(Inherited from TerrainProvider.) |
| GetHeightRelativeToShape(Double, Double, RasterTerrainInterpolator) |
Gets the interpolated height of the terrain at the specified longitude and latitude
relative to the provider's Shape.
This method takes into account the heights of any reference surfaces.
(Inherited from RasterTerrainProvider.) |
| GetHessian | Get the interpolated hessian matrix based on the function of height with respect to the specified longitude and latitude relative to the provider's Shape. This method produces a matrix representing the mixed second order partial derivatives of height in the ShapeFixedFrame. Note: The direction for the gradient and hessian is defined for use with the directional derivative on the surface. The gradient is defined to be orthogonal to the terrain surface with its surface projection in the direction of the greatest increase in the height. To obtain the second directional derivative for the height (acceleration of height along a particular azimuth), take the negative of the hessian then pre and post multiply it by the velocity vector along the desired azimuth. Then add the negative gradient dotted with the derivative of the velocity vector along the surface. |
| GetLocalMinimumSampleSpacing |
Gets the smallest distance between the successive height samples of the terrain data, in radians, at the specified coordinates.
If the return value is 0.0, then the minimum sample spacing is unknown.
(Inherited from TerrainProvider.) |
| GetNormal |
Get the normal vector to the terrain surface at the specified location.
(Inherited from TerrainProvider.) |
| GetPosts |
Gets the posts over a specified area by reading them from the terrain data source. This method is
not expected to do any caching.
(Overrides RasterTerrainProviderGetPosts(RasterTerrainIndexExtent).) |
| GetSecondPartials(Double, Double) |
Get the second order (mixed) partial derivatives of height with respect to the specified
longitude and latitude relative to the provider's Shape.
(Inherited from RasterTerrainProvider.) |
| GetSecondPartials(Double, Double, RasterTerrainInterpolator) |
Get the second order (mixed) partial derivatives of height with respect to the specified
longitude and latitude relative to the provider's Shape.
(Inherited from RasterTerrainProvider.) |
| GetType | Gets the Type of the current instance. (Inherited from Object.) |
| IndexToLatitude |
Gets the latitude, in native units, of the post at a specified index.
(Inherited from RasterTerrainProvider.) |
| IndexToLongitude |
Gets the longitude, in native units, of the post at a specified index.
(Inherited from RasterTerrainProvider.) |
| InGlobalBounds |
Returns if the coordinates are in global bounds which is:
[-π, π] for longitude and
[-π/2, π/2] for latitude.
(Inherited from TerrainProvider.) |
| LatitudeToIndex |
Gets the index of the post at or immediately to the south of the specified latitude.
(Inherited from RasterTerrainProvider.) |
| LongitudeToIndex |
Gets the index of the post at or immediately to the west of the specified longitude.
(Inherited from RasterTerrainProvider.) |
| MemberwiseClone | Creates a shallow copy of the current Object. (Inherited from Object.) |
| PreloadExtent |
Loads the terrain data in a given CartographicExtent into the terrain cache.
This method does not return until the terrain data is fully loaded. All terrain data within the extent is loaded into
memory, even if doing so would exceed the TerrainCacheGroup'sMaximumSize. Furthermore, the loaded terrain data is locked
in memory (meaning it will not be unloaded) until the user calls UnloadExtent(CartographicExtent).
This method is safe to call from any thread.
(Inherited from RasterTerrainProvider.) |
| ProcessCoordinates |
Performs any additional processing of coordinate values prior to using them to load sets of posts
or for interpolating heights. This method is only called if NeedsSpecialCoordinateProcessing
is .
(Inherited from RasterTerrainProvider.) |
| ToString | Returns a string that represents the current object. (Inherited from Object.) |
| UnloadExtent |
Unloads the cached terrain data for a given CartographicExtent.
This method unloads all cached regions where any part of the region falls within
the extent. It does not return until the regions have been unloaded. However,
if a region within the extent is being used in another thread while this method
is executing, the region may be reloaded immediately after this method unloads it.
This method is safe to call from any thread.
(Inherited from RasterTerrainProvider.) |
RemarksThis TerrainProvider has a few limitations that prevent it from reading all USGS DEM files:
- Only the "geographic" ground-planimetric reference system is supported.
- Only the WGS84 horizontal datum is supported.
- Only the local mean sea level (MSL) vertical datum is supported. If the vertical datum is unspecified it is assumed to be MSL.
Attempting to load an unsupported DEM file will result in an InvalidDataException.
See Also