[gdal-dev] VRT pixel functions on tiled vrt

[William Kyngesburye]

So, a vrt of a vrt?

I wanted to avoid that, because as I understand the source, it reads each raster in the derived band as a single numpy array, which would be all the tiled rasters together.  Most of the vrts that I want to process this way are huge, GBs.

I guess I can make a derived band vrt of each tile, then merge those together as a normal vrt.

I already tried running gdal_calc.py on the normal vrts to do the same thing into a geotiff, but it takes forever, while the pixel functions (also python) appear to be much faster.

> On Apr 26, 2018, at 12:41 PM, Even Rouault <even.rouault at spatialys.com> wrote:
> 
> On jeudi 26 avril 2018 08:22:05 CEST William Kyngesburye wrote:
> > I'm trying to add a pixel function (Python) to a vrt where there are
> > multiple rasters (ComplexSource) tiled together (that is, not stacked like
> > an RGB image).  When I translate the vrt to a tif, only the first
> > ComplexSource is processed, the rest on the raster is set to 0.
> > 
> > I got the basics of the functin from the vrt docs, and it does work, for the
> > first raster tile.  Maybe the python notation for calculating the numpy
> > array is wrong?
> > 
> > The original vrt is created from gdalbuildvrt.  This is the vrt thru the
> > first 2 rasters:
>  
> William,
>  
> in a VRTDerivedRasterBand, the sources are considered to be a stack, and in_ar[0] will return the first source and in_ar[1] the seconded one.
>  
> What you need to do is create a regular tiled VRT, and use that one has the single source of a VRTDerivedRasterBand
>  
> Even
>  
> -- 
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-----
William Kyngesburye <kyngchaos*at*kyngchaos*dot*com>
http://www.kyngchaos.com/

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