[gdal-dev] VRT ComputeStatistics fails because of self-reference

[Even Rouault]

Matt,

thanks for the report. I'm a bit surprised this hasn't been reported before as 
it dates back to 1.10.0. Anyway, I've created a ticket 
http://trac.osgeo.org/gdal/ticket/5468 for that issue and pushed a fix for 
1.10, 1.11 and trunk branches.
I cannot think to a workaround, apart from upgrading from sources.

Even

> Hi all,
> 
> I'm trying to compute statistics on a VRT file using the python
> band.ComputeStatistics method.  I'm using GDAL 1.10.1 on a Windows 7
> 64-bit box.
> 
> First, I create a VRT clip of a larger raster using gdal_translate, e.g.
> 
>    gdal_translate -of VRT -projwin <sub_window> in.tif out.vrt
> 
> Then, in Python, I try to compute statistics:
> 
>    ds = gdal.OpenShared('out.vrt', gdalconst.GA_ReadOnly)
>    rb = ds.GetRasterBand(1)
>    (min, max, mean, std) = rb.ComputeStatistics(False)
> 
> This fails with many messages of:
> 
>    ERROR 1: VRTSourcedRasterBand::IRasterIO() called recursively on
>      the same band.
>    It looks like the VRT is referencing itself.
>    ERROR 1: test.vrt, band 29: IReadBlock failed at X offset 1, Y
>      offset 3
> 
> I can replicate the same behavior by first creating the VRT using
> gdal_translate and then calling gdalinfo -stats on it.
> 
> I see in the code that I'm triggering the bAntiRecursionFlag within the
> GetMinimum and GetMaximum member functions, but unclear how this is
> coming about.
> 
> thanks for help,
> matt
> 
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