[postgis-devel] ST_MapAlgebraExpr: Wrong output for Y-data with 'UNION'

[dustymugs]

On 11/21/2011 04:00 AM, Tom van Tilburg wrote:
> Hi List,
>
> Can someone confirm wether I'm doing this wrong or the ST_MapAlgebraExpr
> is doing it wrong:
> I have two overlapping rasters that I want to add to eachother. The
> non-overlapping parts should be included as well and therefore I use
> 'UNION' in the ST_MapalgebraExpr function.
>
> This is my code:
> ====================
> WITH sub as(
> SELECT
> raster1.rast As rast1,
> raster2.rast As rast2,
> ST_MapAlgebraExpr(
> raster1.rast, 1,
> raster2.rast, 1,
> 'rast1 + rast2'::text, NULL::text, 'UNION'::text,
> 'rast2'::text, 'rast1'::text, NULL::Double precision
> ) As rast3
> FROM
> raster1 ,raster2
> )
>
> SELECT
> ST_Ymin(St_Envelope(rast1)),
> ST_Ymax(St_Envelope(rast1)),
> ST_Ymin(St_Envelope(rast2)),
> ST_Ymax(St_Envelope(rast2)),
> ST_Ymin(St_Envelope(rast3)),
> ST_Ymax(St_Envelope(rast3))
> FROM sub
> ;
> =========================
> Result:
> Rast1 Ymin/Ymax
> 443752.035; 456237.035;
> Rast2 Ymin/Ymax
> 446707.035; 456242.035;
> Union Ymin/Ymax
> 443747.035; 456237.035
>
> Whereas the expected output would be:
> Union Ymin/Ymax
> 443752.035;456242.035
>
> (The X-data is outputting correctly).
>
> Regards,
> Tom

Tom,

Can you try r8215.  I believe it has been resolved.  The calculation for 
the upper-left corner in the UNION case was invalid.

-bborie