Memory overflow while using VrayDisplace

[Blakk76]

Hello there.
Recently I`ve faced interesting problem, I was doing kinda "landscape thing" and I have BW bitmap 6000x4000 pixels used as a map for VrayDisplace mod. And I simply couldn't render whole sequence at once, because after about 100-120 frames render was stopped because of various errors. Error messages were different, like "Cannot write image attributes" etc. but the main reason was lack of memory. 32gb of ram are filled 100% and render stops after that, on the memory graph I can see "steps" each frame eats some memory, then next frame adds some more etc...untill whole memory is filled.
Is there a way to avoid this situation? or some workaround with memory filling up?

[Blakk76]

Here you can see "ladder" memory usage, like stuff used for previous frame is still kept in the memory and so on...

[joconnell]

Have you got a moving camera? I'd convert the bitmap to a multires exr to drop come memory, also what's your edge length set at in the vray displace and what's your render resolution?

[Morbid Angel]

Blakk76, you are most likely subdividing the geometry too much.

[Blakk76]

Blakk76, you are most likely subdividing the geometry too much.

only 2000000 triangles
the thing is, it is keeping all the previous data in the memory, like frames are piling up for some reason, I don't see any logical reason for that...it's the same displace, no animation of meshes or someting, only single moving camera

[Blakk76]

Have you got a moving camera? I'd convert the bitmap to a multires exr to drop come memory, also what's your edge length set at in the vray displace and what's your render resolution?

moving Free Cam, I use 2D Mapping (landscape) with default 4 pix edge

[joconnell]

I'd go to 3d and turn view dependent on so you can have worse quality in the background and better quality closer up. We normally use bigger edge lengths than 4 on our environments too, vray will do some clever normal mapping stuff to add in bump detail for anything that wasn't done by polygons. I find sometime's it's better to pre subdivide the mesh using turbosmooth or tesselate in quad mode so vray has less to manufacture.

Another possibility is to do something horrible and just make yourself a gigantic mesh using a high poly grid and the displace modifier, then collapse it to an edit mesh and save to it's own scene or to a vrmesh cache. Xref it back in so you're not saving it every time in the case of edit mesh. Vray can handle a loooot of polygons and this might give you more predictable memory overheads.

[Morbid Angel]

only 2000000 triangles
the thing is, it is keeping all the previous data in the memory, like frames are piling up for some reason, I don't see any logical reason for that...it's the same displace, no animation of meshes or someting, only single moving camera

where did you get that poly count from? Vray does not print any triangulation info.

[Blakk76]

where did you get that poly count from? Vray does not print any triangulation info.

you are right, its the cound of polys before VrayDisplacement, but its still strange, why it eats memory so progressively, like each frame is completely new yet without releasing previous memory

[Morbid Angel]

basically if you use 3d displacement / subdivision and subdivide too high this will happen. You can force vray to subdivide to inslanely high value and run out of ram. Are you using 3d subdiv / displacement? if so, clip the max subdivs to 4, set the view dependent off and set it to a value of 1, and see what happens.