Displacement GI

[fAEkE]

We have tried displacement for leather bump on a couple of car seats and the rendertime increases alot due to swapping geametry when calculating the GI solution. Is there a way to fix this? The only good solution we have come up with is to calculate the IR map without displacement and then render the final image with that map and displacement. The result is the same, but with alot better rendertime.

If this is the only good solution, then it would be awesome to be able to turn of displacement for the GI.

[rivoli]

have you tried adjusting the dynamic memory limit?

[fAEkE]

Increase dynamic memory so vray won't swap as freaquently? No I don't think so, have to try that. It was a while ago we did this test tho so I'm not sure. But still, turning of GI on the displacement modifier would be an awesome feature since you don't need it for such small bumps, and it would also save memory.

[rivoli]

by default the limit is 400mb (vray 1.5 at least), which is simply not enough for most scenes. but yes, I agree that in a case like this, if you can pre calculate the gi solution, it can speed things up.

[fAEkE]

Ye default is 400 still, and set to auto. I made a new test and the result was the same.

First I tried to apply a vray displacement modifier (2d mapping) and vray did not unload geometry while calculating GI, and the rendertime was pretty good, but the modifier breaks my Cad mesh.. so I tried to use material displacement instead (3d mapping) and then vray began swapping like crazy and rendertime went up ALOT. I've tried lower displacement settings and use 1200mb dynamic memory instead, but the renderimes are still extreme.

[jacksc02]

Is the mesh made in max or another CAD programme?
The mesh might need to be subdiveded some more to help the displacement modifier work more efficiently

[fAEkE]

The mesh is unfortunately made in another app and I can't edit it at all.

[jacksc02]

you can add a modifier on top of the stack if the mesh is file linked in

[super gnu]

why cant you edit it? selecting the parts that have displacement on them and adding a subdivide modifier wont change the look of the geometry, but can make massive differences to rendertime when doing displacement. also depending on how much ram you have in your machine, it normally makes sense to use as much as you can for dynamic memory (until you can see your ram getting close to max limit in the task manager) i generally find i can use about 3000 mb of my 6gb.. but then most people have more ram than me.

[fAEkE]

For some reason we can't edit our cad meshes in max. If we add a modifier to it or change to editable poly the mesh just breaks. Some faces will be darker than others, both in viewport and in the renderings.

I found a workaround by misstake a couple of minutes ago. I duplicated the geometry, put a edit mesh modifier and then a vray displacement modifier on top of that. Then the mesh didn't break.. but I hade to duplicate the geometry first, otherwise it breaks :/.... now I don't have an issue with swapping anymore, but rendertimes are a bit high.. but that will just need some ordinary tweaking.

[super gnu]

definbitely reccomend a subdivide modifier on top of the edit mesh... should definitely help with rendertimes.

[fAEkE]

Still can't do that

[super gnu]

strange.. ive brough lots of geometry into max in my time, but ive always managed to get something editable in the end. did you try the "collapse" tool in max? or snapshot perhaps?

maybe the meshes could be exported differently from whatver app they come from?.. from your descriptions of darker faces it sounds like bad normals, and..probably quite a messy mesh youve landed with. particularly if youre planning to animate, id reccomend getting to the bottom of this bit, as a bad mesh can really crap up an animation.

[fAEkE]

Yes your right, the mesh is a mess and it's a normal problem as far as I know. We get the mesh like this, and so far I've just accepted the quality as it is. I'll bring this up with my colleagues to see if it's possible to fix it. And I'll look into the snapshot tool, I'm not familiar with it. Thanks, I'll be back when I get some results

[fAEkE]

I've talked to a colleague and he explained the cad to mesh normal problem.

@super gnu
Have you imported cad to a fairly low poly mesh in max, and then been able to edit it without normal problems?