Opened 5 years ago

Last modified 4 years ago

#1662 new enhancement

[raster] Make a ST_Extent(raster) aggregate taking rotation into account

Reported by: pracine Owned by: pracine
Priority: medium Milestone: PostGIS Future
Component: raster Version: trunk
Keywords: Cc:

Description

Right now we can use ST_Extent(rast::geometry) to get the non rotated extent of a set of rasters but we might want to get the rotated extend instead.

This aggregate should be based on a _st_extent(raster, raster) doing basically the samething as ST_MapAlgebra(,'UNION') when it precompute the size of the resulting raster.

This could then be used by the GDAL driver or any process needing to precalculate the size of a coverage before burning tiles in it.

Change History (6)

comment:1 Changed 5 years ago by pracine

Could or should be called ST_RotatedExtent instead...

comment:2 Changed 4 years ago by dustymugs

Isn't this just a union on the set of convex hulls?

comment:3 Changed 4 years ago by pracine

No because the union does not necessarily result in a nice rectangle if some tiles are missing. here we want the same kind of object as the result of ST_Extent but rotated.

comment:4 Changed 4 years ago by dustymugs

So, 5 vertices in the polygon. Call ST_ConvexHull(geometry) with the final union...

comment:5 Changed 4 years ago by dustymugs

Actually, ST_Extent(rast::geometry) returns the correct (rotated if raster is rotated). The raster cast to geometry uses ST_ConvexHull().

comment:6 Changed 4 years ago by dustymugs

Milestone: PostGIS 2.1.0PostGIS Future
Note: See TracTickets for help on using tickets.