[raster] ST_AsRaster aggregate function

[robe]

Pierre,

Not sure if this is what you had in mind when you said "Burn In" function in your talk. A common need I have which I am sure is that of many BI analysts is the need to show simple thematic maps in reports.

What came to mind to me was an aggregate ST_AsRaster function that takes a set of geomval rows (or multicolumn geom, value) and builds a raster. Basically a reverse of the ST_DumpAsPolgons function.

 http://www.postgis.org/documentation/manual-svn/RT_ST_AsRaster.html This would make it trivial to do a query such as

SELECT ST_AsPNG(ST_AsRaster(gval),300,300) As mymap
FROM (SELECT ROW(ST_Union(geom), SUM(pop))::geomval As gval
FROM sumregion
GROUP BY region_name) As foo;

Which is big considering many report writers allow their picture box controls to be bound to query fields. We might have a new crowd of BI analysts looking to get a piece of PostGIS action.

[pracine]

This is ST_UnionToRaster as planned in Objective FV.19 of the future specs:

http://trac.osgeo.org/postgis/wiki/WKTRaster/SpecificationWorking03

It is dependent on the two raster version of ST_Mapalgebra which is being developed.