[Gvsig_english] Sextante profiles on gvSIG

[fla83tn at libero.it]

Hi to all,
I am experiencing some problems with the profile command of Sextante 
extension.
I would like to know why the computation of profiles requires the 
knowledge of
x and y pixel dimension. Now I will explain myself more widely:


If I have two layers, a DEM and a shape, I know which points are part of the 

intersection of the two. 
With such information I could already add the z-
dimension to the shape (taking it from the DEM raster),
without taking into 
account the x and y pixel dimension. Am I wrong?
I would like to avoid to 
download a DEM at its full resolution to have the correct x and y pixel 

dimension, 
and thus, saving a lot of networking time (required for the 
download of the image).

Best regards,
Flavio