[GRASS-dev] [grass-code R][506] v.what.rast should be able to use other methods like bilinear

[grass-dev at grass.itc.it]

code R item #506, was opened at 2007-10-08 09:26
Status: Open
Priority: 3
Submitted By: William Perkins (perk)
Assigned to: Nobody (None)
Summary: v.what.rast should be able to use other methods like bilinear   
Issue status: None
GRASS component: vector
Operating system: all
Operating system version: 


Initial Comment:
I would like to be able to sample a raster map using bilinear interpolation at points in a vector map.  I want the resulting raster value to end up in an attribute column of the vector map. With existing 6.3 tools, this becomes a several step process. 

v.what.rast does what I need, but only with nearest neighbor sampling.  I could use v.sample, but that creates a new map/table, and the only way to get the attribute back to the original map is to use an SQL join, which is unsupported in dbf and sqlite databases.  v.drape could also be used, but it also creates a new vector map, which has to replace the original, and sometimes the raster information does not make sense as a Z-coordinate.

I've made some changes to v.sample so that it will update a column (and not create a new map).  However, I think the cleanest approach would be to have a new option for v.what.rast.  Furthermore, IMHO, v.rast.what should, through options,  do whatever v.sample does and v.sample should be be eliminated.  

Thanks.

Bill

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