V-Ray Fur crashes 3ds Max

[sheehan_partners_nm]

I have a large open area where I am trying to create 3d grass with Vray fur. It is constantly crashing my scene as the grass is eating all my 32gb of Ram.
What is the best way to optimize memory consumption? Is there any difference if I create the grass using native vray fur, VS scattering around grass elements with Forest Pack?

[sheehan_partners_nm]

No response? How do you guys even render forests and landscapes? They have way more trees!
I took away the fur grass, had to use just a dumb flat texture. I kept in my scene just the trees, vray proxies of course, it consumed all the ram and crashed again!.
Any advice? I am stuck..

[Alex_M]

I don't think the reason for the issue is the scale of the scene. You could easily render really big scenes like forest and such with 32 GB of RAM if you plan it smart and use proxies.

Try to isolate the issue by rendering the scene in groups of objects. Start with rendering everything without proxies and heavy objects. If the RAM consumption is normal, hide everything except the proxies. If the RAM fills up and crashes your rendering, break up the proxies in smaller groups and test each group individually until you find the culprit. Sometimes objects would just break and go "defective" and cause weird stuff to happen during rendering, potentially crashing it. You might have such objects in your scene.

Another reason could be the use of displacement. I had a scene recently where I had displacement on a 10x20m pavement surface and because of some uncollapsed modifiers (I think it was a Shape Merge objects) the RAM would fill all the way up and crash Max. I just converted the Shape Merge object to Editable Poly and reapplied the VrayDispalcement modifierand which fixed the RAM issue. So see if you don't have something similar going on.

Or your scene is just really really huge and even with proxies it won't fit in 32 GB of RAM.

[sheehan_partners_nm]

Hey Alex, thanks for replying!
I did the test. Only the building with the geometry renders fine 18000x1500 pixel for VR in less than 20 minutes.
When I turn on the grass made with Vray Fur, renders fine in small areas. If I turn on all of it, 32gb of ram are not good enough anymore.
Then I jumped to check the proxies. I have trees and bushes. Trees are more in number, heavier in size and render fine as well. If I turn on the bush proxies, then I have a problem. They are the problem. I replaced it with another model of 3d bush, no issue.... There was something bad in the first proxie that eats all the ram. Good to know....
Do you know if there is a difference in making grass with fur or scatter 3d grass? Which one consumes less memory?
I still need to add the grass, as it looks so fake with a flat texture in VR

Thank you.

[Alex_M]

You're welcome, I'm happy you sorted it out.

As for the grass, I just use Forest Pack so I can't really comment on using Vray Fur. I've used it some time ago but on smaller surfaces like front lawns and back yards. It worked pretty well. Not sure how it would behave on very big surfaces though. So maybe just test and see.

[sheehan_partners_nm]

Got it! Ok, will test another day when I'm not under a deadline. Maybe someone from Chaos can tell us which way is better, from a technical/software point of view. They would know....

[svetlozar.draganov]

Then I jumped to check the proxies. I have trees and bushes. Trees are more in number, heavier in size and render fine as well. If I turn on the bush proxies, then I have a problem. They are the problem. I replaced it with another model of 3d bush, no issue.... There was something bad in the first proxie that eats all the ram. Good to know....
Do you know if there is a difference in making grass with fur or scatter 3d grass? Which one consumes less memory?

It might be a good idea to send this that scene and proxy for investigation, it could be a bug that needs to be addressed.
Did you checked the quality of the geometry of that bush for some bad data like overlapping faces, flipped normals etc?

Regarding the choice between V-Ray Fur or other grass alternatives like Forest Pack, MultiScatter etc, I'm not 100% sure but as far as I know even though they are working with dynamic geometry it's being translated to a static geometry once passed to V-Ray for rendering which is no longer dynamic geometry. V-Ray Fur however is truly dynamic geometry which is only generated when needed and removed as soon as it's no longer in usage, so it should be a more memory optimized than its scatter alternatives. This statement of course is only applicable for bucket-rendering, for progressive rendering that shouldn't make any difference because it doesn't benefit from dynamic geometries since everything should be loaded into the memory during the whole rendering process.
Let me try to find someone from our Dev Team to confirm if the above is 100% true.

[sheehan_partners_nm]

It might be a good idea to send this that scene and proxy for investigation, it could be a bug that needs to be addressed.
Did you checked the quality of the geometry of that bush for some bad data like overlapping faces, flipped normals etc?

No, I didn't check the quality of the model. It is a 3d bush I bought online. If you give me your email, I can send that to you for investigation.

V-Ray Fur however is truly dynamic geometry which is only generated when needed and removed as soon as it's no longer in usage, so it should be a more memory optimized than its scatter alternatives.

This is what I thought as well, something Vray native should be more optimized than an external plugin. That's why I created my grass with Fur in first place.
Thanks for your answers Svetlozar!

[svetlozar.draganov]

You may send the scene to support@chaosgroup.com
Please include a link to this thread so we could track where it comes from easily.

[sheehan_partners_nm]

Just did. Thank you!