[gdal-dev] How to pick on file from a VRT ?

[Vincent Honnet]

Hi,

I would like to do something like a picking on a vrt.
Let me explain:
I have vrt's from GTiff files but there is some holes, areas where there 
isn't any data.
 From an area defined by its coordinates I would like to get the 
information if this area is pointing on a file or not, or at least on 
data or not.
Is there a way to do that ? I'm using GDal 1.7.

Thanks a lot in advance,

Vincent