[X32Wright]

I dont think you understand the enormity and complexity of tree interaction and the resulting increase in polygon load. Surely there would be programmed to have localized adaptive subdivision when it comes to collision detection based on proximity of a plane to the ground and trees but those would still require enormous resources (CPU,GPU and polygon load). Most GPU today are not made for handling enormous polygon loads but rather are optimized for enormous TEXTURE handling instead as well as shader processing and some geometry calculations. They aren't geared for handling 'interactive' 4 million polygon scenes at all (although they might be able to load that in memory but not interactively) while the CAD workstation cards are (which renders everything accurately and NOT cheat like the game cards which do not render everything), although things are changing.

Computation based on the height will work since they trees and such are placed on 'height field' generated terain as it is already but even with a simple 4 triangle tree that would require more resources and more polygons to pull off IF you want interactivity with the plane instead of a simple collision detection that we have now. I am asuming that the collision detection (plane vs ground or trees collision detection) in the game isnt even collision detection per se but rather based on the coordinates of the plane's axis. IF the computed vector (for the plane) falls beyond the 'ZERO ground axis' the plane is designated as crashed. But this is a guess. Having to apply this to trees is a waste of time. This is why we crash on the large 'invisible trees' (which are 'height displaced geometry' (pancaked) mapped with alpha channels to look like forrests) but pass through the ones that look and feel solid (those with swaying detailed leaves).

As for better craters well, Oleg can always implement bump mapping and procedural displacement (even animated) but didnt chose to do so in Il-2. My guess would be due to the video cards' capability limitations when Il-2 was released.