Changes between Version 62 and Version 63 of WKTRaster/SpecificationWorking01

Timestamp:

Dec 16, 2009, 11:15:21 AM (14 years ago)

Author:

pracine

Comment:

—

WKTRaster/SpecificationWorking01

@@ -192 +192 @@
 '''ST_Box2D(raster) -> BOX2D''' - Returns a BOX2D representing the maximum extents of the geometry.
 
+ The only difference with ST_Envelope(raster) is that ST_Box2D(raster) returns a BOX2D, not a geometry.
+
  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).
 
@@ -198 +200 @@
  If the raser is rotated, the envelope is a non-rotated box enclosing the rotated raster.
 
+ The only difference with ST_Box2D(raster) is that ST_Envelope(raster) returns a geometry, not a BOX2D.
+
  This function should replace the actual ST_raster_envelope() function which is wrongly named.
 
 '''ST_ConvexHull(raster) -> polygon geometry''' - Returns the minimum convex geometry that encloses every significant pixel from the raster. 
 
- 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).
+ 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).
+
+ A ST_ConvexHull(raster, 'WITHNODATA') variant SHOULD 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).
 
 '''ST_Shape(raster) -> polygon geometry''' - Returns a geometry encomparsing every pixel having a significant value (different than the NODATA value).
 
- This polygon geometry might contain holes if some internal areas of the raster contain pixels with NODATA values.
+ This polygon geometry might contain holes if some internal areas of the raster contain pixels with NODATA values. By opposition ST_ConvexHull(raster) never contains holes.
 
 '''ST_AsPolygon(raster) -> polygon geometry set''' - Returns a set of geometry, one for each group of pixel having the same value.
@@ -216 +222 @@
  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().
 
+ This function is at the base of the first version of ST_Intersection which compute the intersection between a raster and a geometry.
+
 '''ST_AsSmoothPolygon(raster) -> polygon geometry set''' - Returns a set of geometry, one for each group of pixel having the same value.
 
@@ -226 +234 @@
 
 
-'''ST_Intersects(raster|geometry, raster|geometry)'''[[BR]][[BR]]
-'''ST_Intersection(raster|geometry, raster|geometry, ‘raster’|’geometry’)->raster/geometry'''[[BR]]
+'''ST_Intersects(raster|geometry, raster|geometry)'''
+
+'''ST_Intersection(raster|geometry, raster|geometry, ‘raster’|’geometry’)->raster/geometry'''
 
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