Changes between Version 38 and Version 39 of WKTRaster/SpecificationWorking02


Ignore:
Timestamp:
09/21/10 08:04:55 (14 years ago)
Author:
pracine
Comment:

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  • WKTRaster/SpecificationWorking02

    v38 v39  
    3737 Returns a one band raster which pixel values are the mathematical expression of another raster band.
    3838
    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"
     39 The expression is any PostgreSQL valid expression returning a number. This expression can contain any user-defined function. 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'
    4040
    4141 An extra nodata value expression, applying only to nodata values pixel, can be provided.
     42
     43 It is not possible yet to refer to neighbour pixel values.
    4244
    4345 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.