Changes between Version 61 and Version 62 of WKTRaster/SpecificationWorking01
- Timestamp:
- Dec 16, 2009, 11:06:54 AM (14 years ago)
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WKTRaster/SpecificationWorking01
v61 v62 190 190 '''Function definitions for WKT Raster 0.1.6''' 191 191 192 '''ST_Box2D(raster) -> BOX2D''' Returns a BOX2D representing the maximum extents of the geometry.192 '''ST_Box2D(raster) -> BOX2D''' - Returns a BOX2D representing the maximum extents of the geometry. 193 193 194 194 This function replaces ST_Raster_to_box2d() and should be used for the "raster AS box2d" cast. It should also be used instead of ST_raster_envelope when creating indexes in gdal2wktraster.py (to be tested). 195 195 196 '''ST_Envelope(raster) -> polygon geometry''' Returns the minimum bounding box for the supplied raster, as a geometry.196 '''ST_Envelope(raster) -> polygon geometry''' - Returns the minimum bounding box for the supplied raster, as a geometry. 197 197 198 198 If the raser is rotated, the envelope is a non-rotated box enclosing the rotated raster. … … 200 200 This function should replace the actual ST_raster_envelope() function which is wrongly named. 201 201 202 '''ST_ConvexHull(raster) -> polygon geometry''' Returns the minimum convex geometry that encloses every significant pixel from the raster.202 '''ST_ConvexHull(raster) -> polygon geometry''' - Returns the minimum convex geometry that encloses every significant pixel from the raster. 203 203 204 204 By default the resulting polygon TAKES the NODATA values into account. The resulting polygon enclose only pixels having a significant value (different than the NODATA value). The ST_ConvexHull(raster, 'WITHNODATA') variant DO NOT TAKE the NODATA value into account. It generally returns a square or rectangle polygon that can be rotated or not depending on the rotation of the raster. If the raster is not rotated ST_ConvexHull(geometry, 'WITHNODATA') is (almost) equivalent to ST_Envelope(raster). 205 205 206 '''ST_Shape(raster) -> polygon geometry''' - Returns a geometry encomparsing every pixel having a significant value (different than the NODATA value).206 '''ST_Shape(raster) -> polygon geometry''' - Returns a geometry encomparsing every pixel having a significant value (different than the NODATA value). 207 207 208 208 This polygon geometry might contain holes if some internal areas of the raster contain pixels with NODATA values. 209 209 210 '''ST_AsPolygon(raster) -> polygon geometry set''' Returns a set of geometry, one for each group of pixel having the same value.210 '''ST_AsPolygon(raster) -> polygon geometry set''' - Returns a set of geometry, one for each group of pixel having the same value. 211 211 212 212 The shape of each polygon should exactly follow pixels edges. … … 216 216 This function should be used with precaution on raster with float pixel type as it could return one polygon per pixel. This kind of raster should be reclassified (using the planned ST_Reclassify(raster,...) function) before using ST_AsPolygon(). 217 217 218 '''ST_AsSmoothPolygon(raster) -> polygon geometry set''' Returns a set of geometry, one for each group of pixel having the same value.218 '''ST_AsSmoothPolygon(raster) -> polygon geometry set''' - Returns a set of geometry, one for each group of pixel having the same value. 219 219 220 220 The shape of each polygon is smooted to remove stair effects.