Vray + Multiscatter + Max Crashing During Render

[theeastcoastwest]

Hello,

 

I have been having a seriously annoying issue with the Multiscatter plugin as of late. Relatively small scene without too many scatter objects.

 

Vray 2 updated.

Max 2012

Multiscatter 1.1.xx (on a different machine can't remember specific release)

Vray memory set to dynamic @ 10000 gb

All Materials Vray.

 

Intel chipset

12gb ram

ati graphics

 

So, the problem is during light cache calculation, max just crashes completely. The scene is roughly 550k polys, which is on the low side for what my machine usually is handling. I am using MS to scatter 1 bunch of grass, and one unique tree. So after my scene was crashing, I exported just my house model out and started anew. Grass scattered on simple plane, I'm just testing some new models, and set to max 100,000 instances.

 

It was rendering fine, then I added in the tree to another plane and it started crashing. I also had 1 other unique tree in the scene at this point, but it was not being scattered. I set the tree that I was scattering to have a max of 35 instances. CRASH.

 

I re-opened the scene and deleted everything except the original plane and grass scatter objects, that was rendering successfully, and it still crashed.

 

I cannot for my life figure out why it is crashing, and especially what I am doing that makes a scene that was rendering fine at the beginning, start crashing max.

 

Anyone have any ideas?

 

I am strongly considering just going with another scatter plugin.

[icube]

Light Cache is very fast algorithm, but there are some drawbacks. Light Cache needs much more RAM than other V-Ray GI algorithms. MultiScatter is tool for creating huge amount of geometries which also needs RAM.

therefore there is a big chance to encounter problems (very slow rendering or crashing) when you use LC with MultiScatter.

 

So using Light Cache in exterior visualisation consumes lots of memory wherever you are using MultiScatter or not,

and its just our very general recommendation not to use it, unless you really know what you are doing and have tons of memory.

[theeastcoastwest]

Thanks for the advice. I wasn't really aware that light cache used such a larger amount of Ram compared to other GI solutions.

 

I figured out the problem though, and it wasn't a memory issue.

 

Multiscatter can't handle normal maps in the bump slot for some reason? Regular maps work fine in there. Some of the models I was scattering were using normal maps in the bump slots.

 

Cooking with grease now though!

[icube]

its documented in the manual, this is V-Ray issue not MultiScatter

http://docs.rendering.ru/en:multiscatter#using_normalbump

"Please check that you are not using NormalBump with V-Ray, use VrayNormalMap instead (please refer to V-Ray support for this issue)"

[theeastcoastwest]

Wow, I missed that completely. Thanks a lot for that tid bit. I'll try to swap out controllers next time and see if it avoids the crashing issue. It is a bit odd, however, that vray will render the maps fine until I proxy and scatter them.

[icube]

Basically speaking, it may render fine with small CPU or RAM errors, which may be unnoticed when rendering a single object, but when you multiply it thousands or millions times with MultiScatter that problem will just grow exponentially and crush the system

[moreans]

Thanks alot man

its documented in the manual, this is V-Ray issue not MultiScatter

http://docs.rendering.ru/en:multiscatter#using_normalbump

"Please check that you are not using NormalBump with V-Ray, use VrayNormalMap instead (please refer to V-Ray support for this issue)"