Error building Embree static ray caster, error message: [EmbreeRayServer::doBuildSDTree] 3: Setting vertex buffer failed

[yavor.rubenov]

Hello,

but I cannot see where it says that button won't work if you have the VrayDisplacementMod applied to the object.

It is there but to be honest - I also missed it on first glance. Forwarded a note to the Docs team to make it a bit more visible as it is an important bit of information.

I also think an earlier reply where someone said, "It's the RAM" didn't help. At no point did I ever get to the limit, or even near the limit, of my RAM. I think what's really going on is a limitation within VRAY that we all keep hitting.

It is a RAM issue but a bit more complex than pure maximum available RAM limit . Let me try to explain how it goes (it will also help with some other questions). When beginning a render V-Ray goes trough all scene objects and generates triangle meshes from them. Displacement is a bit more complex but with defaults (static pretesselated displacement) it ends up being the same. All the triangles of all meshes are stored in one location. Once all those static triangles are gathered we need to build an Embree raycasting acceleration structure. Having all the triangles in one structure has one main benefit - it is faster to trace rays in it.. It has some drawbacks and V-Ray has other options too.

The process of building the Embree raycasting acceleration structure comes next. It needs to process all the triangles (at times more than once) so again for faster processing we need to allocate one *continuous* big chunk of memory for all of them. Embree does its processing, builds the structures and then the big chunk of memory is not needed and freed.

The various messages related to EmbreeRayServer errors happen when allocating that big chunk of memory (well it is not only one but a few big chunks so you can get a few different messages).

A few takeaways:
- While you may have enough free RAM for that big chunk - there is no guarantee that you have a continuous one. We ask the operating system for it and it may or may not have it at the given moment.
- There is no one specific geometry that causes that error itself. It is the total number of triangles and the current memory conditions that lead to it.

I'd like to see a more thorough debug log, it would have really helped me.

There's not much more info to write in the log for that specific error unfortunately. We'll try to add some additional information that could help tracking it down though - I'm thinking about adding some short list like which the 10 geometries with most faces in your scene are.

Best regards,
Yavor

[Vizioen]

There's not much more info to write in the log for that specific error unfortunately. We'll try to add some additional information that could help tracking it down though - I'm thinking about adding some short list like which the 10 geometries with most faces in your scene are.

Well there's the memory tracking, maybe there can be a full list there of objects and their RAM usage? Might also bug the documentation team about that because the link that refers to the memory tracking page is non existing: System - V-Ray for 3ds Max - Global Site (chaos.com)

[Joelaff]

Unless I'm not following anymore but it states in the first sentence: The settings in this rollout control the displacement of objects with displacement materials that do not have a VRayDisplacementMod modifier applied.

It’s there, but some emphasis, like “if and only if” the modifier is not applied might be helpful.

I got this part right away, the part that took me longer to understand is that you can use the modifier to alter settings for the default displacement.

[RobH22]

I'll read all of the threads and try the solutions but I just started experiencing the exact same issue. I couldn't render anyhting over 1920. It came out of the blue and it's one I've never seen before. Because of the discussion above, to me it sounds like it could be a bug in a recent update. I'll report back what I determine.

[RobH22]

Where can I download 'previous versions?' I've found documentation for them and info, but only the latest version has a download link. I'd like to revert back and see what happens.

Edit: Found it. I was looking for Max 2025 and it has no previous versions. I see the tick box for Max 2024's previous releases.

Edit2: After some additional testing I don't think it's a bug not the new release. I reverted back in Max 2024 and still had the problem. I thought then that it might the the 6.5million poly file. But I opened a different file that has 22million polys and it renders fine. There is somehting in my file and it's not 'Displacement' as none of the objects have it. In fact, I converted every object to an Editible Poly to make sure and it still won't render a large file. I'll keep playing. When I figure it out I'm come back and report my findings. Unfortunately none of the ones above help me. I do still find it odd that a few people all of a sudden have this and I've never seen this issue before. Strange coincidence?

[Vizioen]

To be sure it's not displacement you have to turn it off in the render settings, it could still be in a material. If you want you could upload a stripped scene with the problematic geometry and we could take a look.

[RobH22]

Vizioen I appreciate that. I didn't turn it off in the render settings and was unaware I could, so thanks for that oversight on my part. But, I went through all of my materials, there are about 60 and I found one with displacement. It was a Substance. As soon as I unhooked its displacement, things rendered.

But here's the odd part. This is a Substance I've used for a few years on similar models. It's always rendered fine. But last week, with nothing having changed in the file or the material, it didn't. And the issue happened to pop up near the same time as the original date of the @simon_kotowicz post. Super odd.

Anyway, I'm OK now, I can render. If I reconnect the Substance's displacement, no matter how small the displacement is, it fails to render large files. Later I'll redo the Substance but am on a deadline. But at least I now now it "is" definately 'displacement' related and disabling that gets me rendering 4K again.