Changes between Version 25 and Version 26 of WKTRaster/SpecificationWorking02


Ignore:
Timestamp:
09/03/10 14:23:10 (14 years ago)
Author:
pracine
Comment:

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  • WKTRaster/SpecificationWorking02

    v25 v26  
    1818== '''Objective B02x - Implement better support for NULL, Empty, !HasNoBand(rast), !HasNoBand(rast, band) and !BandIsNoData rasters in all functions.''' ==
    1919
    20  Each function shoul better handle NULL rasters, empty rasterm rasters with no band and bands only filled with nodata values.
     20 Each function should better handle NULL rasters, empty rasterm rasters with no band and bands only filled with nodata values.
    2121
    22  * Generally, when NULL rasters are provided, return NULL. If the function involves a second non NULL raster and something can be done with it, do it.
    23  * Generally, when empty rasters are provided (ST_IsEmpty, width=0 or height=0), return an empty raster. If the function involves a second non empty raster and something can be done with it, do it.
    24  * Generally, when a !HasNoBand(rast) or a !HasNoBand(rast, band) raster is provided return a raster with no band but with the right extent. If the function involves a second raster having a band or the band, treat the first missing band like a !BandIsNoData.
    25  * A !BandIsNoData raster is a normal raster but many functions can be optimized with this type of raster.
    26  * All functions having missing the requested information (about its extent when it is a NULL or an empty raster or about its band when it is a !HasNoBand(rast) or a !HasNoBand(rast, band) raster) should return NULL or a documented value.
    27  * Try as less as possible to return EXCEPTION (or ERROR).
     22  1) Generally, when NULL rasters are provided, return NULL. If the function involves a second non NULL raster and something can be done with it, do it.
     23
     24  2) Generally, when empty rasters are provided (ST_IsEmpty, width=0 or height=0), return an empty raster. If the function involves a second non empty raster and something can be done with it, do it.
     25
     26  2) Generally, when a !HasNoBand(rast) or a !HasNoBand(rast, band) raster is provided return a raster with no band but with the right extent. If the function involves a second raster having a band or the band, treat the first missing band like a !BandIsNoData.
     27
     28  4) A !BandIsNoData raster is a normal raster but many functions can be optimized with this type of raster.
     29
     30  5) All functions having missing the requested information (about its extent when it is a NULL or an empty raster or about its band when it is a !HasNoBand(rast) or a !HasNoBand(rast, band) raster) should return NULL or a documented value.
     31
     32  6) Try as less as possible to return EXCEPTION (or ERROR).
    2833
    2934'''ST_IsEmpty(rast) -> boolean'''