[gdal-dev] Zonal statistics with GDAL/StarSpan

[Greg Ederer]

Thanks, Brent.  I'll give this a whirl.

Cheers,

Greg

Brent Fraser wrote:
> Greg,
>
>  OpenJump is a good topology/geometry fixing tool.  Load your 
> shapefile and do Tools->Generate->Buffer, set the Buffer distance to 0 
> to clean up the polygon vertices.  I seem to recall it may have a 
> problem preserving attributes when the results are saved as a 
> shapefile, but you may be able to just use the new .shp portion with 
> the old .dbf and .shx if the resulting geometry records are not 
> re-ordered.
>
> Brent
>
>
>
> Greg Ederer wrote:
>> Brent,
>>
>> My Google search didn't turn up much of use (most of the results were 
>> PostGIS-specific).  Do you know of a tool that would tell me which 
>> feature(s) have problems?  Do you know of a tool that might be able 
>> to fix these polygons?
>>
>> Thanks!
>>
>> Greg
>>
>> Brent Fraser wrote:
>>> Greg,
>>>
>>>  It means the GEOS topology library is having problems with geometry 
>>> of your input shapefile.  Most likely related to duplicate vertices 
>>> (or near-duplicate) in a polygon.  Do a Google for "side location 
>>> conflict".   It would be nice if it spat out the FID of the 
>>> offending polygon...
>>>
>>> Brent
>>> Greg Ederer wrote:
>>>> Hi Brent,
>>>>
>>>> Thanks for the example.  Here's what I got:
>>>>
>>>> Macintosh-4:starspan_tests gregederer$ starspan2 --progress --RID 
>>>> none --vector 
>>>> /Users/gregederer/servers/geoserver_data/data/shapefiles/Admin/afadmn2n.shp  
>>>> --raster rfe_2006_04_pct.tif --stats  results.txt avg
>>>> starspan: --out-prefix: ?
>>>> Type `starspan --help' for help
>>>>
>>>> I then added a --out-prefix, like so:
>>>>
>>>> Macintosh-4:starspan_tests gregederer$ starspan2 --progress --RID 
>>>> none --vector 
>>>> /Users/gregederer/servers/geoserver_data/data/shapefiles/Admin/afadmn2n.shp  
>>>> --raster rfe_2006_04_pct.tif --stats  results.txt avg --out-prefix bar
>>>> starspan: --out-type: ?
>>>> Type `starspan --help' for help
>>>>
>>>> I then added '--out-type table' (I found in the source that valid 
>>>> --out-types are: table, mini_raster_strip, mini_rasters, 
>>>> rasterization):
>>>>
>>>> Macintosh-4:starspan_tests gregederer$ starspan2 --progress --RID 
>>>> none --vector 
>>>> /Users/gregederer/servers/geoserver_data/data/shapefiles/Admin/afadmn2n.shp  
>>>> --raster rfe_2006_04_pct.tif --stats  results.txt avg --out-prefix 
>>>> bar --out-type table
>>>> Number of features: 550
>>>> starspan_csv:   1: Extracting from rfe_2006_04_pct.tif
>>>>        0% terminate called after throwing an instance of 
>>>> 'geos::util::TopologyException'
>>>>  what():  TopologyException: side location conflict -8.25 23.1536
>>>> Abort trap
>>>>
>>>> Any idea what the TopologyException indicates?
>>>>
>>>> Thanks!
>>>>
>>>> Greg
>>>>
>>>> Brent Fraser wrote:
>>>>> Greg,
>>>>>
>>>>>  I've used StarSpan to do similar things; in my case I wanted 
>>>>> "mode" not "avg".  Using v1.2.01 (I don't think I made major mods 
>>>>> to the source):
>>>>>
>>>>>     starspan2.exe --progress --RID none --vector boundaries.shp  
>>>>> --raster big.tif --stats  results.txt mode
>>>>>
>>>>> I edited the resulting results.txt text (csv) file and used GDAL's 
>>>>> ogr2ogr to do a join on the shapefile's DBF file based on the FID.
>>>>>
>>>>> Brent Fraser
>>>>>
>>>>>
>>>>> Greg Ederer wrote:
>>>>>> Hello all,
>>>>>>
>>>>>> I'm a GDAL newbie.  I have a shape file containing subnational 
>>>>>> boundaries for Africa.  I have a raster containing rainfall for 
>>>>>> Africa.  I need to pull out the spatial average of rainfall for 
>>>>>> each of the subnational units.
>>>>>>
>>>>>> I think that I might be able to pull this off using StarSpan.  
>>>>>> But, the docs on the StarSpan wiki do not line up with the 
>>>>>> current version of the program (the changelog mentions that 
>>>>>> certain command line switches have been eliminated, and others 
>>>>>> added; but it doesn't say what the new switches do, or how to use 
>>>>>> them).  I am digging through the StarSpan sources to try to 
>>>>>> figure out how to use it.
>>>>>>
>>>>>> Does anyone have any suggestions as to how I might get the needed 
>>>>>> data using GDAL (with, or without StarSpan)?
>>>>>>
>>>>>> Thanks!
>>>>>>
>>>>>> Greg
>>>>>>
>>>>
>>>>
>>
>>


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