Changes between Version 10 and Version 11 of WKTRaster/FAQ

Timestamp:

Mar 22, 2010, 11:16:28 AM (14 years ago)

Author:

pracine

Comment:

—

WKTRaster/FAQ

@@ -22 +22 @@
 In a traditional raster system only the global image is georeferenced, not every tile. The system assume that the area covered by the tiles forms a perfect rectangle well aligned on a grid. This is the raster view of geospatial data. However the reality is often different. People use raster data covering area for which the sum of the tiles do not necessarily result in a rectangle. This is the coverage view of raster geospatial data. Having one georeference per tile allow WKT Raster to store raster coverage which are not necessarily rectangular.
 
-They also often need to convert vector data to raster data in order to perform certain operations. If you convert a vector coverage containing gaps or overlaps to raster, you may result in way too much information or in a lost of information. In WKT Raster each vector object convert to a single raster. Having one georeference per tile (or raster) is very usefull to properly support this feature.
+People also often need to convert vector data to raster data in order to perform certain operations. If you convert a vector coverage containing gaps or overlaps to raster, you may result in way too much information in the first case (gaps are filled with data) or in a lost of information in the second case (overlaps are blended or only one polygon is converted). In WKT Raster each vector object convert to a single raster so that there is a one to one correspondence between the two. Having one georeference per tile (or raster) is very usefull to properly support this feature.
 
 '''5 - How come it is possible to store overlapping rasters in the same table? In a raster, tiles should not overlaps.'''