[postgis-users] raster intersect with polygon resulting in false NULL value

Wed Aug 21 12:54:35 PDT 2013

Her table constraints indicate that the NODATA value is properly set to
-9999.

-bborie

On Wed, Aug 21, 2013 at 12:51 PM, Tim Keitt <tkeitt at utexas.edu> wrote:

> Gdal is honoring the no-data value encoded in the raster file, but postgis
> is not. I see this problem in a lot of code out there.
>
> THK
>
>
> On Wed, Aug 21, 2013 at 2:26 PM, Hailey Eckstrand <
> haileyeckstrand at gmail.com> wrote:
>
>>  Hello,
>> I am trying perform aggregate statistics on a raster vector overlay with
>> a polygon of 192 sub polys. Many of the resulting 192 mean values are
>> correct.. however, I am encountering that one vector overlay mean is NULL
>> which I know to be incorrect. The polygon and raster are in the same
>> projection and when I look at them in QGIS they are overlaid correctly and
>> I can see that the polygon is over top of ~30 raster cells that are all the
>> value 3 (it is not over top of any NA values). One thing that is sort of
>> fishy is that QGIS is reading the raster statistics and no data value
>> incorrectly (values included below) compared to the base ascii raster
>> gdalinfo which is included below.
>>
>> My query:
>>
>> select bid,(ST_SummaryStatsAgg(ST_Clip(rast,1, geom, true))).mean
>> FROM aet_1,(select * from zben_allwshds where bid = 61) foo
>> WHERE ST_Intersects(rast, geom)
>> GROUP BY bid
>> order by bid;
>> NOTICE:  The two rasters provided have no intersection.  Returning no
>> band raster
>> CONTEXT:  PL/pgSQL function "st_clip" line 39 at assignment
>> NOTICE:  Could not find raster band of index 1 when setting pixel value.
>> Nodata value not set. Returning original raster
>> CONTEXT:  PL/pgSQL function "st_clip" line 41 at assignment
>> NOTICE:  Invalid band index (must use 1-based). Returning NULL
>> CONTEXT:  PL/pgSQL function "raster_summarystatsstate" line 9 at
>> assignment
>> SQL function "raster_summarystatsstate" statement 1
>>  bid | mean
>> -----+------
>>   61 |
>>
>>
>> Query which returns all the Summary Stats (order of stats is count | sum
>> | mean | stddev | min | max)
>>
>> select bid,(ST_SummaryStatsAgg(ST_Clip(rast,1, geom, true)))
>> FROM aet_1,(select * from zben_allwshds where bid = 61) foo
>> WHERE ST_Intersects(rast, geom)
>> GROUP BY bid
>> order by bid;
>> NOTICE:  The two rasters provided have no intersection.  Returning no
>> band raster
>> CONTEXT:  PL/pgSQL function "st_clip" line 39 at assignment
>> NOTICE:  Could not find raster band of index 1 when setting pixel value.
>> Nodata value not set. Returning original raster
>> CONTEXT:  PL/pgSQL function "st_clip" line 41 at assignment
>> NOTICE:  Invalid band index (must use 1-based). Returning NULL
>> CONTEXT:  PL/pgSQL function "raster_summarystatsstate" line 9 at
>> assignment
>> SQL function "raster_summarystatsstate" statement 1
>>  bid | st_summarystatsagg
>> -----+--------------------
>>   61 | (,237,,,3,3)
>>
>>
>>
>> The raster was loaded into postgresql with the raster2pgsql tool:
>>
>> raster2pgsql -s 3005 -I -C -M aet_1.asc -F -t 100x100 public.aet_1 | psql
>> -d NWBC
>>
>> gdalinfo of the loaded raster:
>>
>> gdalinfo aet_1.asc
>> Driver: AAIGrid/Arc/Info ASCII Grid
>> Files: aet_1.asc
>>        aet_1.asc.aux.xml
>> Size is 2331, 2895
>>  Coordinate System is `'
>> Origin = (173461.904000000009546,1929781.912000000011176)
>> Pixel Size = (400.000000000000000,-400.000000000000000)
>> Corner Coordinates:
>> Upper Left  (  173461.904, 1929781.912)
>> Lower Left  (  173461.904,  771781.912)
>> Upper Right ( 1105861.904, 1929781.912)
>> Lower Right ( 1105861.904,  771781.912)
>> Center      (  639661.904, 1350781.912)
>> Band 1 Block=2331x1 Type=Float32, ColorInterp=Undefined
>>   Min=0.000 Max=9.000
>>   Minimum=0.000, Maximum=9.000, Mean=1.955, StdDev=2.375
>>   NoData Value=-9999
>>   Metadata:
>>     STATISTICS_MAXIMUM=9
>>     STATISTICS_MEAN=1.9546895049572
>>     STATISTICS_MINIMUM=0
>>     STATISTICS_STDDEV=2.3747620319231
>>
>> Incorrect QGIS Raster Statistics:
>>
>> STATISTICS_MAXIMUM=1.2341209168929e+033
>>
>> STATISTICS_MEAN=5.9293249344197e+031
>>
>> STATISTICS_MINIMUM=-9999
>>
>> STATISTICS_STDDEV=2.4574481861697e+032
>>
>> NODATA VALUE= -32768
>>
>> PostGIS raster info:
>>
>>   rid serial NOT NULL,
>>   rast raster,
>>   filename text,
>>   CONSTRAINT aet_1_pkey PRIMARY KEY (rid),
>>   CONSTRAINT enforce_height_rast CHECK (st_height(rast) = 100),
>>   CONSTRAINT enforce_max_extent_rast CHECK
>> (st_coveredby(st_convexhull(rast),
>> '0103000020BD0B000001000000050000001D5A643BAF2C0541FCA9F1D2EB7D27411D5A643BAF2C0541FED478E935723D41448B6CE7954B3141FED478E935723D41448B6CE7954B3141FCA9F1D2EB7D27411D5A643BAF2C0541FCA9F1D2EB7D2741'::geometry)),
>>   CONSTRAINT enforce_nodata_values_rast CHECK
>> (_raster_constraint_nodata_values(rast)::numeric(16,10)[] =
>> '{-9999}'::numeric(16,10)[]),
>>   CONSTRAINT enforce_num_bands_rast CHECK (st_numbands(rast) = 1),
>>   CONSTRAINT enforce_out_db_rast CHECK (_raster_constraint_out_db(rast) =
>> '{f}'::boolean[]),
>>   CONSTRAINT enforce_pixel_types_rast CHECK
>> (_raster_constraint_pixel_types(rast) = '{32BF}'::text[]),
>>   CONSTRAINT enforce_same_alignment_rast CHECK (st_samealignment(rast,
>> '0100000000000000000000794000000000000079C01D5A643BAF2C0541FED478E935723D4100000000000000000000000000000000BD0B000001000100'::raster)),
>>   CONSTRAINT enforce_scalex_rast CHECK (st_scalex(rast)::numeric(16,10) =
>> 400::numeric(16,10)),
>>   CONSTRAINT enforce_scaley_rast CHECK (st_scaley(rast)::numeric(16,10) =
>> (-400)::numeric(16,10)),
>>   CONSTRAINT enforce_srid_rast CHECK (st_srid(rast) = 3005),
>>   CONSTRAINT enforce_width_rast CHECK (st_width(rast) = 100)
>>
>>
>>
>> Install info:
>>
>> PostgreSQL Version 9.1
>>
>> postgis_full_version:
>>  POSTGIS="2.0.1 r9979" GEOS="3.3.8-CAPI-1.7.8" PROJ="Rel. 4.8.0, 6 March
>> 2012" GDAL="GDAL 1.9.2, released 2012/10/08" LIBXML="2.7.8" TOPOLOGY RASTER
>> (1 row)
>>
>> QGIS version:
>> 1.8.0-Lisboa
>> Compiled against GDAL/OGR
>> 1.9.2
>> Running against GDAL/OGR
>> 1.9.2
>> GEOS Version
>> 3.3.8
>> PostgreSQL Client Version
>> 8.3.10
>>
>>
>> Sorry for all the extra information, I just don't know what people need
>> to know to help. Thanks in advance!
>>
>> Hailey
>>
>>
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>>
>>
>
>
> --
> http://www.keittlab.org/
>
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