big mesh

[Ibear888]

I'm working on a landscape file including meshes that cover several acres. The file size ranges from about 400mb to 2gb depending on what 3dm files or Blocks I bring together.

When adding trees and other 3D models, whether from V-ray cosmos or commercial suppliers, Vray frequently crashes. I'm trying to use vrmesh, vrscene, vrmat and blocks to minimize file size.

I'm finding 3D file downloads contain a huge number of vertices. I'm using Rhino mesh Reduce to reduce the size. If I reduce an oak tree from 2,000,000 vertices to 50,000, which sounds like a big reduction, it may or may not crash. If I reduce the mesh to 2000 vertices, the tree looks sick.

What is a v-ray manageable number of vertices for a far away mesh object? For a close to camera object? How does overall file size interplay with v-ray crashing? Is there a practical limit?

I find bits of advice here and there, but is there a book or guide somewhere to the secrets of large file management? Trial and error is not working well.

Any advice or tutorial suggestions are appreciated.

Thanks, Jeff

[rene_rapati]

I have a landscape model of ±60 square km. It consists of tens of thousands of meshes. The model is about 1,6GB.
And yes Rhino and/or V-ray become very slow when I work on this model. Saving takes a few minutes.

I think this is normal behaviour.

Are you using v-ray scatter to place your trees in the model?
I have used this in combination with a lot of trees/rocks/plants form the cosmos browser. And although there are some serious problems with scatter and other v-ray geometries, this seems to work a lot better than to add lots and lots of trees as blocks.
Using displacement geometries can also cause a lot of lag...

One other thing that may help is to place your landscape near the origin (0,0) of the model.
Initially my model was about 45km away from the origin. When I tried to render it, the textures were all wrong. Moving everything near the origin fixed this problem.

Using linked blocks could significantly help working on large models, but unfortunately this causes all kinds of trouble with v-ray geometries.

[Ibear888]

Rene, thank you for the comments.

I came across this thread from one year ago ... Error : Exception in CORE: Internal error. Please save and restart as soon as possible! My experience is very similar. One time a render takes 20 seconds and another time it takes 5 minutes - or crashes.

I receive the out of core crash regularly. I've broken files into smaller files to use as blocks where I work on one block while inserting others for geometry references. This has not significantly helped. V-ray seems to function more reliably when I'm not using blocks and when the file size is less than about 300mb, which is not very practical for my work. My machine has 128gb of ram and two 4090, but the model worked better in the preceding vray and rhino versions with 32gb of ram and two 1090ti cards.

I have not tried scatter, yet. I'd like to have more predictability before engaging another feature. I've tried splitting a 1GB file into two 500mb files and making one a block and inserting it in the other. Not effective. I've tried the vrmesh, but it does not retain materials. I've tried vrscene, but it appears to slow things down. I've tried making a vrmesh into a block with its materials and had some success. I've tried saving a vrmesh as a vrmat - does not retain materials outside of the original file. I have reduced all downloade meshes to less than 50k vertices - maybe they need more reduction. I've set chaos assets to low resolution. I've not been able to get to where I could have success inserting many tree blocks. My landscape meshes are only about 3000 feet from the origin. Generally, I"m turning displacement off until I get past the out of core crashing. I'd like to have a better understanding of how v-ray is handling the cosmos assets.

I've signed up for a one hour meeting with tech support, but does anybody know of a reliable expert resource for hire? Too much trial and error.

thanks again
Jeff

[rene_rapati]

Which v-ray version are you using? And which rhino version?
In have been using the latest v-ray 6 update 2.4 for the last few months. This version is (very) far from perfect, but crashes a lot less than the previous versions. Most of the previous version were so bad I could not work with them without crashing rhino multiple times per hour. The error you encounter has not shown up for me for a long time now.

I would strongly advise you to explore the possibilities of v-ray scatter. As I said, this helped me a lot with dressing up my landscape.

Having used AutoCAD for a long time, I am used to using xrefs (linked blocks) to counter problems with large models. Using this approach with v-ray is almost impossible due to the problems with linked blocks. Unfortunately using normal blocks with v-ray geometries is also not ideal.
My approach for the last few weeks has been to separate the model into smaller parts which I work on separately. Only when they are finished I combine them in one large model. I usually copy from one file to another instead of importing or inserting as a block. This way it is less likely that v-ray geometries are suddenly missing form the model.

[Ibear888]

Rene,
I am using v-ray 6 version 2.4. Interestingly, where I am beginning to have success has been evolving toward the same direction as your comments. I deleted vrmats and vrmesh as blocks, reduced files size to eliminate all types of blocks and reimported chaos assets. I"m finding proxy vrmesh seems to work within the file it originates, but affiliates with instability when imported to another file. I regularly reset the asset editor and vfb (inconvenient, but helps). It seems that once I strip out blocks and other objects or materials not originating in the open file, that I have better results. An inefficiency, as you have found, is that I will have to bring the smaller files back together each time I need to render or work on a larger area.

I have yet to distill this into a paradigm of predictability.

I'll try the scatter feature and report.

Thank you for your comments.
Jeff

[rene_rapati]

[...]
I have yet to distill this into a paradigm of predictability.
[...]

Be careful not to spend too much time on this. New problems are introduced with every update it seems... So a workflow that might work now, might not work for the next update.
I have spent countless hours trying to finish my projects by working around the bugs, but most of the time I only noticed too far in the process that other things were still going wrong.

I sincerely hope that the next update will fix the problems with linked blocks. This was promised to me before, but has not made it to updates yet. Using linked blocks should really help working on large projects.

Did you already have the one hour meeting with tech support? I'm interested to know if they have a specific workflow for large models.

[Ibear888]

I sunk a lot of time into trying to make blocks and imports work. Now - I"m loading most assets from Chaos Cosmos rather than the Library (vrmat, vrmesh or vrscene) and using no blocks. Things are working much better.

I think the Library contained v-ray 5 materials and assets which do not play well with v-ray 6. (The v-ray Library of materials, vrmats and vrscenes is inefficient since - for me - it is not showing easily observed previews.) If I purchase a 3D model, such as an oak tree, it can be trouble. It seems to work best to reduce and repair the mesh, assign materials to it myself and Copy it within the file rather than make it into a block. My focus was on converting an import mesh to a vrmesh or vrscene (within a block or not) to import to another file. Commonly crashes. I'll try creating a vrmesh and repeating it (more than two or three times) in its home file.

I've not yet had the one hour meeting. I did submit two files as inter-related blocks totaling about 1GB - tech support said they found no problem - but I don't know how they tested it or to what extent they tried to render it. I ran the V-ray render times and my machine appears to run correctly.

If I get more info about large file operation, I'll be sure to post it.
thanks,
Jeff