Changes between Version 21 and Version 22 of WKTRaster/GDALDriverSpecificationWorking

Timestamp:

Feb 17, 2011, 3:08:34 PM (13 years ago)

Author:

pracine

Comment:

—

WKTRaster/GDALDriverSpecificationWorking

@@ -86 +86 @@
 
 Once constructed the basic structure (GDALDataset object and related GDALRasterBand objects), you need to choose the strategy for raster data reading/writing:
+
   * ''Natural'' block oriented r/w: The driver reads/writes data in equal sized blocks. The potentially more efficient way of r/w data. Really, the natural block size for this dataset is chosen during GDALRasterBand creation. So, '''it's driver's responsibility to provide the desired value for block size'''. To use this method, your driver must provide an implementation of [http://www.gdal.org/classGDALRasterBand.html#09e1d83971ddff0b43deffd54ef25eef IReadBlock].
+
   * Region oriented r/w: The driver reads/writes arbitrary regions of data. It's a potentially less efficient method, because you have to take care of '''data type translation''' if the data type of the buffer is different than that of the GDALRasterBand. You also must takes care of '''image decimation / replication''' if the buffer size (nBufXSize x nBufYSize) is different than the size of the region being accessed (nXSize x nYSize). To use this method, your driver must provide an implementation of [http://www.gdal.org/classGDALRasterBand.html#5497e8d29e743ee9177202cb3f61c3c7 IRasterIO].
+
+ '''Pierre question:''' In which case "the data type of the buffer is different than that of the GDALRasterBand"?
 
 Clearly, there's no best method for reading/writing data in our case. In the ideal case of regulary blocked rasters, with no overlapping and same grid for all tiles, the block oriented r/w is the more appropiate strategy. But in the rest of the cases, a more general r/w method must be provided.