About Reduced Resolution Dataset (RRD) files |
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Release 9.1
Last modified September 16, 2005 |
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When you choose to build pyramids, this information is stored in a Reduced Resolution Dataset (RRD) file, with the same filename as the dataset.
A requirement for building an RRD file for a raster dataset is to have write access to the directory where the dataset resides. The RRD file will be created in the same directory as the source dataset when you choose to build pyramids. The next time you add this raster dataset, these pyramids will be used. One exception to this rule is ERDAS IMAGINE files, where the pointer to the pyramids is stored in the image file rather than an auxillary (AUX) file like other formats. In this case you must have write access to the raster dataset and the directory in which it resides.
For decompressed rasters, the minimum RRD file size is approximately 8 percent of the size of the original raster dataset. In certain situations, however, the size of the RRD file created can be larger than the original file, depending on the compression technique used in the original raster file. If your RRD file exceeds two gigabytes, then a Reduced Resolution Dataset External (RDE) raster data file is created as a supplementary file.