Changes between Version 32 and Version 33 of WKTRaster/SpecificationFinal01


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Timestamp:
08/27/10 12:31:47 (14 years ago)
Author:
pracine
Comment:

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  • WKTRaster/SpecificationFinal01

    v32 v33  
    220220 2) If the first test returns TRUE, it checks if the geometry returned by ST_ConvexHull(raster) intersects with the geometry.
    221221
    222  3) If the second test returns TRUE, it checks if the geometry returned by ST_Polygon(raster, integer) intersects with the geometry. This test is slower since it involve the computation of the raster shape and it might involve the geometry shape. This test takes NODATA values into account. i.e. A geometry intersecting only with a NODATA value area of a raster is NOT actually not intersecting with this raster. This behavior may be controled by limiting the test to certain conditions as stated below.
    223 
    224  Variant 4 proceeds in a very similar way except that convex hulls of both rasters are computed and compared in step 2) and both shape of raster are computed and compared in step 3).
     222 3) If the second test returns TRUE, it searches for a with value pixel touching the geometry. As soon as one pixel with value is found the function returns TRUE. A geometry intersecting only with a NODATA value area of a raster is NOT actually intersecting with this raster. This behavior may be controled by limiting the test to certain conditions as stated below.
    225223
    226224 If you want to limit the intersection test to the first condition, simply use the && operator. The raster and the geometry will be casted to their respective bounding box (box2d objects):