The others have had some pretty good ideas about this. My question to you
is: What are you comparing against? What file format are you receiving data
in?
One problem you are up against is how are you going to get the original
volume? If you have IGES, SW has to translate it just to find it's volume.
You might use Rhino if you have it since it is going to leave the data
pretty much alone on translation.
The other thing I would watch for is a file where fillets and other
difficult geometry may have been replaced by surfaces in the original.
If you have the luxury, try bisection when doing volumes. In other words,
compare:
A. Both wholes
A1. Left half
A1a. Left half top
A1b. Left half bottom
A2. Right half
A2a. Right half top
A2b. Right half bottom
and so on. If something is moved you will eventually find it this way. Again
you need a way to do this in both the source system and SW.
Also, benchmark the source system volume calculation with SW.
Also, you could use a system like Rhino to overlay both the original and
translation.