[gdal-dev] GDAL Error 1: TIFFFetchDirectory:Sanity check on directory count failed . . .

[Even Rouault]

Le samedi 29 janvier 2011 15:16:01, Neil Best a écrit :
> How should I interpret this error?
> 
> GDAL Error 1: TIFFFetchDirectory:Sanity check on directory count failed,
> this is probably not a valid IFD offset
> 
> I saw this in an R session.  I descibe the context on Stackoverflow:
> 
> http://stackoverflow.com/questions/4831882/mysterious-error-from-foreach
> 
> There I describe that I am wrapping a function from library(raster), which
> uses rgdal, with a foreach construct and parallelizing using
> multicore/doMC. I suspect that this and other errors have something to do
> with file I/O but I'm not sure how to interpret them or track them down. 
> Thanks for any suggestions.

Neil,

First, does the opening of the TIFF file with a utility such gdalinfo works 
without emitting this warning ? If it works, then your code is the likely 
culprit, otherwise the TIFF file is corrupted.

I don't know how you use the multi threading, but this could certainly be the 
responsible for the error : you cannot use the same GDAL dataset object from 
multiple threads, even if you just use it for reading. If you want to do 
parallelized I/O, you need to open as many dataset objects as you have threads 
(you can open several datasets pointing to the same file). See 
http://www.gdal.org/classGDALDataset.html#6764788806a1785c97036d1dba064497

Best regards,

Even