Changes between Version 34 and Version 35 of WKTRaster/SpecificationWorking02


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Timestamp:
Sep 21, 2010, 7:52:27 AM (14 years ago)
Author:
pracine
Comment:

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  • WKTRaster/SpecificationWorking02

    v34 v35  
    3535'''ST_MapAlgebra'''
    3636
    37  Returns a one band raster as the mathematical expression of another raster band.
     37 Returns a one band raster which pixel values are the mathematical expression of another raster band.
    3838
    39  The resulting raster conserve the size, the georeference, the alignment and the SRID of the provided raster. The pixel type of the resulting raster might be specified. An extra nodata value expression, applying only on nodata values, can be provided.
     39 The expression is any PostgreSQL valid expression returning a number. In the one raster version of ST_MapAlgebra, the value of the current pixel is expressed in the expression by "rast". E.g. "cos(rast)" or "rast / 2"
     40
     41 An extra nodata value expression, applying only to nodata values pixel, can be provided.
     42
     43 In the one raster version of ST_MapAlgebra, the resulting raster conserve the size, the georeference, the alignment and the SRID of the provided raster.
     44
     45 The pixel type of the resulting raster can be specified as '1BB', '2BUI', '4BUI', '8BSI', '8BUI', '16BSI', '16BUI', '32BSI', '32BUI', '32BF' or '64BF'. If the expression results in a value out of the range of the specified pixel type, it is truncated.
    4046
    4147 '''Variants'''