Exports one or more layers to a new gridded elevation file. If NULL is passed for the layer list, all elevation layers will be saved to the new elevation file, otherwise only the specified layer will be exported. If NULL is provided for the world bounds, all available data will be exported, otherwise only data within the specified bounds will be exported.

The new elevation file create will be in the current view projection as returned by the GM_GetProjection function. You can change the view projection, and thus the export projection, by calling the GM_SetProjection function.

The aExtraFlags parameter allows the specification of any extra options not supports in the aFlags parameter. The options should be specified with the option name, followed by an equal sign, followed by the option value. Most users will pass NULL for this value unless they need a non-default value for an extra option. Currently the following extra options are supported:

VOID_VALUE (GeoTIFF format only) - specifies the void value to use for the export. By default the commonly used -32767 is used, but you can add this parameter to specify any valid signed 16-bit integer to use, like VOID_VALUE=-9999 to use -9999.
ROUGHNESS_LAYER_LIST (WindSim GWS format only) - specifies the layer indices (0-based) for those layers that are roughness rather than elevation in the provided list of elevation layers. For example, if the 2nd and 3rd layers in the list are roughness, use "ROUGHNESS_LAYER_LIST=1,2". Only required if the roughness grids were created outside the SDK and loaded as elevation grids. Otherwise this is automatically determined.
ADD_COLORS (VRML format only) - controls whether or not a color value is written out for each VRML vertex from the input layers. By default this is enabled, use "ADD_COLORS=NO" to disable adding colors.
DELIM (XYZ ASCII grid format only) - specifies the coordinate delimiter to use. The default is a comma, but special keywords of COMMA, SPACE, and TAB are supported. For example to use a space as the delimiter use "DELIM=SPACE". This is supported in the SDK v13.2.0 and higher.

Syntax

Copy

GM_DLL_EXPORTED GM_Error_t32 __stdcall GM_ExportElevationEx
(
const char*                     aFilename,      // Name of new file to create
GM_ElevationExportFormat_t32    aFormat,        // Format to export
GM_LayerHandle_t32*             aLayerList,     // List of layers to export or NULL for all
uint32                          aLayerCount,    // Number of layers in list (0 for all)
const GM_Rectangle_t*           aWorldBounds,   // World bounds to export or NULL for all
sint32                          aPixelWidth,    // Width in samples of new image
sint32                          aPixelHeight,   // Height in samples of new image
GM_RasterExportFlags_t32        aFlags,         // Export flags
GM_ElevUnits_t8                 aElevUnits,     // Elevation units for export, if applicable
const char*                     aExtraFlags     // Additional text-based flags for some formats (use NULL for defaults)
)