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

[Matt Gregory]

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