Hi Matt,

If 3dresample changes the data type of the warp field to float, that would defintely cause problems.  Unfortunatley I don't have a readily available program to that could resize the warp fields to match a new target size.  

But I am surprized that 3dwarper is not working for the 512x512x97 size.  The only think I can suggest is to use the original size images (512x512x97) but give 3dwarper the following additional option: -iter1 0

This will prevent the proram from using the full resolution.

Babak