Changes between Version 64 and Version 65 of WKTRaster/SpecificationWorking01


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Timestamp:
Dec 16, 2009, 11:36:29 AM (14 years ago)
Author:
pracine
Comment:

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  • WKTRaster/SpecificationWorking01

    v64 v65  
    211211
    212212 A ST_ConvexHull(raster, 'WITHNODATA') variant SHOULD NOT TAKE the NODATA value into account. It generally returns a square or rectangle polygon that can be rotated or not depending on the rotation of the raster. If the raster is not rotated ST_ConvexHull(geometry, 'WITHNODATA') is (almost) equivalent to ST_Envelope(raster).
     213
     214 '''Implementation details'''
     215
     216 The first variant ST_ConvexHull(raster) could be roughly implemented with a SQL or PL/pgSQL function looking like 'SELECT '
    213217
    214218'''ST_Shape(raster) -> polygon geometry''' - Returns a geometry encomparsing every pixel having a significant value (different than the NODATA value).