I'm using both packages and generally concur with the comments above.<br>IMO Vapor is better at subsetting data fields and has superior volume rendering capabilities. For those with experience with visualisation tools the ability to control lighting, and hand tool transfer functions etc is useful. The trajectory analysis capability is a big plus ( adding capability to derive system relative trajectories wld be a bonus for meteorological analysis). It would be good to have more derived variables available and built-in map capabilities, but I would not like it become as complicated and <a href="http://multi-purpose.as">multi-purpose.as</a> IDV. The capability to export to open source plotting packages (rather than the expensive IDL) wld be helpful.<br>
On a modest, now outdated, single processor PC with a recent, cheap ($30-40) GeForce 256 Mb card it works well.<br>Echoing Leigh's comment- Vapor is superior if you want to view your visualisation problem from a fluid dynamical viewpoint.<br>
I've been working on a high-resolution simulation of a 'real case' intense ana-cold front (I think this is your area)-if you'd like to see some images let me know,<br>regards,<br>David<br>