Changes between Version 229 and Version 230 of WKTRaster/SpecificationWorking03


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Timestamp:
Jul 27, 2012, 1:26:53 PM (12 years ago)
Author:
pracine
Comment:

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  • WKTRaster/SpecificationWorking03

    v229 v230  
    9090 See also: [wiki:WKTRaster/MapAlgebra Notes taken by David Zwarg during the Montreal Code Sprint 2011] and ticket #860.
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    9393== '''Objective FV.25 - Optimized version of two rasters ST_MapAlgebra()''' ==
    9494
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    9797 * The prototype of an optimized version, trying to set those large areas of nodata values as well as areas where only one raster is present (this is the case when unioning two contiguous non-overlapping rasters) as a block (not pixel by pixel or in a "memset manner") is still in development. See http://trac.osgeo.org/postgis/browser/trunk/raster/scripts/plpgsql/st_mapalgebra_optimized.sql The idea is to set blocks of the resulting raster using ST_SetValues() (described in [http://trac.osgeo.org/postgis/wiki/WKTRaster/SpecificationWorking02 Objective 2.0.05]) instead of processing one pixel at a time. This is somewhat similar to setting a large block of memory with memcpy() or memset() rather than setting a buffer one value at a time. The resulting raster is divided into rectangular block with the _MapAlgebraParts() function.
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    99100== '''Objective FV.26 - ST_Difference() and ST_SymDifference() based on ST_MapAlgebra(raster, raster)''' ==
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    106107 See at the end of [http://trac.osgeo.org/postgis/browser/trunk/raster/scripts/plpgsql/st_mapalgebra.sql plpgsql/st_mapalgebra.sql][[BR]]
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    109110== '''Objective FV.27 - Integrate different custom functions, to be used with ST_MapAlgebraFct(), to extract values from a coverage''' ==
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    141142  * from a line coverage could also be LENGTH_MAX, LENGTH_MIN, LENGTH_RANGE, LENGTH_SUM, LENGTH_MEAN, LENGTH_STDDEV, LENGTH_OF_BIGGEST_VALUE, LENGTH_OF_SMALLEST_VALUE, LENGTH_OF_MOST_FREQUENT_VALUE, LENGTH_OF_LEAST_FREQUENT_VALUE, VALUE_OF_LONGEST, VALUE_OF_SHORTEST, VALUE_OF_COMBINED_LONGEST, VALUE_OF_COMBINED_SHORTEST. To be continued...
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    143145== '''Objective FV.28 - Add some function interpolating a raster from a geometry layer''' ==
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