[GRASS-user] v.rast.stats skipping polygons. Why?

[Hernán De Angelis]

Hola Vero,

Thank you. There were a few repeated or shared categories but not as 
many as skipped polygons. The problem was with the data like many 
extremely small lakes and a too coarse raster resolution to capture all 
of them them. This is solved now.

All well, thanks again

/Hernán


Den 2023-10-31 kl. 23:47, skrev Veronica Andreo:
> Hola Hernán,
>
> Do your polygons have repeated/shared cat values? That might be one 
> potential cause according to the Notes in the manual: 
> https://grass.osgeo.org/grass83/manuals/v.rast.stats.html
>
> just my 2 cents
> Vero
>
> El mar, 31 oct 2023 a las 6:35, Hernán De Angelis via grass-user 
> (<grass-user at lists.osgeo.org>) escribió:
>
>     Hi all,
>
>     I have a vector layer with 97015 polygons (lakes in real life)
>     many of
>     which are complicated, with islands. The layer has been cleaned using
>     v.clean (during import, and after as well). I then run
>     v.stats.rast to
>     pick statistics from a raster. This works well for about 3/4 of the
>     categories while about 1/4 are skipped. Why?
>
>      From v.stats.rast:
>     WARNING: Not all vector categories converted to raster. Converted
>     73078 of
>               97837.
>     Processing input data (73078 categories)...
>
>     I see that v.to.rast has no problems converting polygons to raster
>     (only
>     visually checked). A test running v.rast.stats using the rasterized
>     vector reports:
>     WARNING: Not all vector categories converted to raster. Converted
>     97015 of
>               97837.
>     Processing input data (97015 categories)...
>     That is, it converts all polygons.
>
>     I have cleaned, and rebuilt topology to no avail. Also calling
>     v.rast.stats using layer (1) and type (centroid) did not change
>     the results.
>
>     Am I missing something here? Why is this happening and what can be
>     done
>     to calculate raster statistics for all polygons?
>
>     Thanks in advance!
>
>     Hernán
>
>
>     v.category report is:
>      > v.category input=lakes option=report
>     Layer/table: 1/lakes
>     type       count        min        max
>     point          0          0          0
>     line           0          0          0
>     boundary       0          0          0
>     centroid   97837          1      97015
>     area           0          0          0
>     face           0          0          0
>     kernel         0          0          0
>     all        97837          1      97015
>     Layer: 2
>     type       count        min        max
>     point          0          0          0
>     line           0          0          0
>     boundary       0          0          0
>     centroid      21          2          2
>     area           0          0          0
>     face           0          0          0
>     kernel         0          0          0
>     all           21          2          2
>
>
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