Volumetric Grid Rendering

[Kalmandru]

Hey Guys, I' ve got a couple of questions regarding rendering the volumetric grid in Vray. First of all, is there some more in depth documentation except the vray for maya documents, maybe some tutorials explaining the workflow, and some more in depth explaining of the parameters? Secondly, I'm not getting anything in the render elements, nothing in the normals, velocity and depth pass! I activated seperate channel for Volumetric Normals and Standard channel for Volumetric ZDepth in the Render Elements, but nothing appears! Do i have to create a new render element, or whats the workflow, so that the volume grid appears in the render elements? Do I have to render in Progressive or Bucket Mode? Do I have to set the Render Mode for the Volume Grid other than Volumetric? I tested switching to Volumetric Geometry and Progressive, but then i can't render anymore, because i get the following Error message:

Unhandled exception occurred, will exit render loop. Unhandled exception c0000005

Had a look in the forums section, but couldn't find any helpful info!

appreciate any feedback or in depth information
Thanks Guys,
Chris

[georgi.zhekov]

Hello,

You will need to use Volumetric Geometry mode in order to get proper Render Elements with VRayVolumeGrid.
As for the unhandled exception - are you using the latest V-Ray version?

If you use the latest V-Ray version and it's still crashing - can you please send a scene to support@chaosgroup.com with V-Ray version, Maya version and OS details so we can find out what is wrong?

Thank you,

[Kalmandru]

Hey georgi,

thanks for the reply. We are currently running on Vray 3.52.01. Should we update?

I have another question regarding Volume Grid rendering: i created a new render layer and wanted to override the visibility of the Volume Grid by activating the Matte Surface, so that the Grid renders as a black matte, but the secondary rays are visible. But when i render the matte doesn't seem to work/override! How can i use the Volume Grid as a matte for my render Layer?

thx Chris

[georgi.zhekov]

Hey - it should work with 3.52 so if possible please send the scene to support so we can debug it.

As for the mattes - this still need to be implemented for volumetrics I'm afraid.

It should work for meshes though.

[Kalmandru]

Hey georgi,

thanks for the info. I have one more question gegarding the Volume Grid rendering: Which Render Elements do i have to output, so that our compositing department can rebuild the beauty in Nuke! I there any special things to watch out? Can Smoke and Fire for example be seperated by render elements?

thanks, have a good weekend

[georgi.zhekov]

The separation of Fire and Smoke is a bit tricky as we don't have dedicated Render Elements for them yet. Using the VRayAtmosphere pass you can get the Fire and Smoke together. You could extract just the fire using the VRaySelfIllumination element. And after that by subtracting the Fire you can get the smoke.

[Kalmandru]

Hey georgi,
thanks for the info. I have another question regarding volume grid vdb sequence rendering via deadline. We have a shot with a frame range of 100 frames, but the explosion is only at the end of the shot, for the last 30 frames. Now when we submit the scene to the farm, the clients crash and give error messages, saying they can't find the cache files for the frames were there are no cache files, because we don't need them there! What can we do about that, is ther any parameter or checkbox we have to enable, or do we have to set something particular in houdini or the vdb sequence? Can we set/clamp the cache sequence in vray. Here' the error message from deadline:

2017-09-07 17:59:14: 0: STDOUT: [2017/Sep/7|17:59:14] V-Ray warning: [PhoenixCachePlugin] Frame data 1122000 can't be loaded from V:/VFX/STKC_StarTrekCorvan/Projectfiles/457/006/3dfx/Houdini/Explosion_LargeScale/vdb/stkc_457_006_3dfx_Explosion_v004_fch/Explosion_005/Explosion_005.#####.vdb.

2017-09-07 17:59:14: 0: STDOUT: [2017/Sep/7|17:59:14] V-Ray warning: [PhoenixSimPlugin] No simulation data for time 1122!


Thank you
Chris

[Kalmandru]

i would really appreciate a quick anwer, deadline for project is tomorrow!!

thanks

[georgi.zhekov]

You can try and disable the "Strict Error checking" in the Advanced options of the Deadline submission. This will ignore the warning and it should render.