OTOY Forums

Hi,

I'm experimenting with the new volume rendering features and I've encountered a confusing issue. I noticed that all the renders I was doing through the Modo plugin appeared blockier than expected. Eventually I realized the voxel resolution is down-scaled once it enters the Octane plugin. To test, I imported the smoke1.vdb from http://www.openvdb.org/download/ and rendered it in Modo and exported the scene to Octane Standalone for comparison. The exported voxels are lower res. I don't know how to get good voxel shading in Modo, but the actual grid seems to be the resolution of the original file, so the down-scaling seems to happen on the way into Modo Octane.

Any ideas why this happens?

EDIT: btw I'm using 3.4.4.114, I tried it before upgrading as well, forget which version that was. I'm using Modo 10.2.

The following pre-release tries to resolve this issue. Can you ple let me know how you go with it?

https://render.otoy.com/customerdownloa ... _64bit.exe

3.4.4.115
- Reworked the Unreal Shader conversion as per the node layout provided by user "jonathan"
- The Environment Map gamma and invert channels are now read from the current frame rather than frame 0, so can now be animated
- Fixed bug when editing the Modo Material for a Volume which was causes an Octane Log error
- Changed the loading of VDB files to increase voxel resolution

Paul

There was an issue with the installer from the above link. The corrected link is https://render.otoy.com/customerdownloa ... _64bit.exe

Paul

Tested some more, and it works with the new build - Thanks!

I'm curious though, what causes the resolution to change? I tested on a huge voxel grid just now and the resolution seems to actually have increased after going through Modo Octane:
http://screencast.com/t/dah5IocSRa
http://screencast.com/t/m0QUnNKF

Tested some more, and it works with the new build - Thanks!

I'm curious though, what causes the resolution to change? I tested on a huge voxel grid just now and the resolution seems to actually have increased after going through Modo Octane:
http://screencast.com/t/dah5IocSRa
http://screencast.com/t/m0QUnNKF

In summary - Octane is not reading the VDB directly. Instead, the plugin is querying the .VDB file through Octane to get the resolution, and this resolution is then being used to sample each point in the volume in Modo. Unfortunately Modo places .VDB files differently to Octane - so it's necessary to get the "Modo version" of the Volume information, rather than simply supplying Octane with the .VDB filename in order to get Octane to match Modo. If the increase in resolution is an issue, let me know (and provide the .vdb you are using for testing) and I can try to get a closer match.

Paul

Thanks for the explanation. I haven't noticed any actual issues so far, but I've only just started playing with it. The voxel res is 25% larger but I'm not sure if that affects render times much, and I doubt I'll use assets of that size frequently.