RpfDataSet.RasterCachePolicy Property
Gets or sets a value indicating the type of raster caching the dataset should use.
Syntax
public RasterCachePolicy RasterCachePolicy { get; set; }Property Value
Default: None
A value indicating the type of raster caching the dataset should use.
This property can only be modified before the dataset has been initialized. Attempting to modify it after initialization will cause an exception to be thrown.
Remarks
Some Carmenta Engine datasets can create a raster cache to speed up access to the raster data. The raster cache will be created the first time the dataset is loaded, and saved to a file in the directory specified by the IndexPath property.
If this property is set to Overviews, the dataset will read all dataset files and sort them into groups with identical raster properties (format, color table et cetera). For each of these groups it will create a tile pyramid of raster overviews, each level down-sampled by a factor of 2 from the previous level. All the overview tiles for all pyramids will be saved to the raster cache file. When the dataset needs to read low-resolution raster data for a zoomed-out view scale, it can read just the required overviews instead of the original, high-resolution data. This can dramatically increase reading performance for zoomed-out view scales.
The overview functionality provided by Overviews is similar to the GDAL overviews supported by GdalDataSet (see GdalDataSet.CreateOverviews). It is recommended to use Overviews, because it can often create larger, more efficient overviews.
If this property is set to Full, the full resolution data will also be saved to the cache, in addition to creating and saving overviews as described above. This will require additional disk space, but it can increase performance significantly if the original data is stored in a format that is slow to read, like GridASCII or poorly tiled TIFF files. With this type of raster cache, the original data will never be accessed again, unless you also specify VerifyIndexFiles, or change the properties of the dataset.
If this property is set to None, no raster cache will be created, and the dataset will always read from the original data files.
Platforms
Windows, Linux, Android