Joan,
I think your expression is wrong.
'kb1.rast+kb.rast'
should be:
'rast1+rast2'
Oddly enough, I would not expect this error message with that error, so
I'm curious wether it will make a change. Could it be there is any more
quotes in the query that we can't see?
Chrs,
Tom
On 22-11-2011 14:24, Joan wrote:
Hi Bborie,
I have used ST_MapAlgebraExpr but I get the error below.
select * from (select ST_MapAlgebraExpr(kb.rast, kb1.rast,
'kb1.rast+kb.rast') as rast from kb_dsm_clip kb, kb_dsm_clip100 kb1)
as r1 limit 5;
ERROR: missing FROM-clause entry for table "kb1"
LINE 1: SELECT (KB1.RAST+KB.RAST)::double precision
^
QUERY: SELECT (KB1.RAST+KB.RAST)::double precision
^
At what point should I add :: double precision, I added it like this
and also got an error.
select * from (select ST_MapAlgebraExpr(kb.rast, kb1.rast,
'kb1.rast+kb.rast')::double precision as rast from kb_dsm_clip kb,
kb_dsm_clip100 kb1) as r1 limit 5;
ERROR: cannot cast type raster to double precision
LINE 1: ...AlgebraExpr(kb.rast, kb1.rast, 'kb1.rast+kb.rast')::double p...
^
Regards
Joan
On 21 November 2011 16:06, Bborie Park <[email protected]
<mailto:[email protected]>> wrote:
On Mon, Nov 21, 2011 at 7:02 AM, Joan <[email protected]
<mailto:[email protected]>> wrote:
> Hello,
>
> When I run the following query
> select ST_MapAlgebra(r1.rast, r2.rast, "rast1 + rast2") from (select
> r1.rast, r2.rast from r1, r2) as foo limit 10;
> I get this error
> ERROR: column "rast + rast" does not exist
> LINE 1: ...t * from (select ST_MapAlgebra(r1.rast, r2.rast,
"rast + ra...
> ^
> What could be the problem? What is the correct syntax for
st_mapalgebra?
> I have PostGIS installed the version updated on 18th Nov 2011.
>
> Joan
Hey Joan,
You'll want to use ST_MapAlgebraExpr or ST_MapAlgebraFct.
http://postgis.refractions.net/documentation/manual-svn/RT_reference.html#Raster_Processing
-bborie
--
Bborie Park
Programmer
Center for Vectorborne Diseases
UC Davis
530-752-8380
[email protected] <mailto:[email protected]>
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