[Gdal-dev] Problems with gdal_grid

PikoBoZ piklas at gmail.com
Fri Apr 18 08:12:35 EDT 2008


Hi List
Thanks to Andrey and Tamas for their useful answers about .vrt
I managed to write a simple .vrt and to interpolate my point values using -a
invdist.
I'm now trying to control my layer style and nodata
I understood that i must use the ComplexSource to perform such tasks, as
Tamas show me an example.
Is the ComplexSource must be embedded into the
<OGRVRTDataSource></OGRVRTDataSource>, or must it comes after, or may be in
a different file ?
In fact i don't get the solution to link the VRTDataSource and the
ComplexSource
Any hints appreciated

Nicolas B.


PikoBoZ wrote:
> 
> Hi List !
> 
> I've got troubles experimenting gdal_grid interpolation algoritms
> I want to interpolate ponctual values contained in a point .shp (or csv),
> and to write the result as GTiff
> I use the following command yet:
> 
> [code]
> gdal_grid -a invdist:power=2.0smooting=1.0 -txe 679285 681415 -tye 1837728
> 1840022 -of GTiff -ot Float32 -l vectorial_plume vectorial_plume.shp
> testwrite.tiff
> [/code]
> 
> testwrite.tiff is created but corrupted:
> - It is mono band greyscaled, and i'd like to get a RGB, in the aim to
> apply style
> - It is all black (NoData). I think that gdal doesn't know on which field
> to work on (in the dbf) so it can't interpolate any values !
> 
> So, a few questions is persiting in my mind:
> Is it simpler to interpolate from .shp or to use a .vrt / .csv couple ?
> How can I specify to gdal_grid a data field to interpolate?  
> Is it possible to get a RGB GTiff from gdal_grid and to apply style
> (killing nodata, Min/Max colors...)
> 
> Many thanks by advance
> 
> Nicolas BOZON
> Maths/GIS PhD student
> 
> 
> 
> 
> 
> 

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