OpenSubdiv does not match in vray standalone

[jovcem]

Im having trouble matching a look with open subdiv properties in a vrscene file.
I cant match the look from 3ds max with openSubdiv modifier with osd_subdiv_* properties on a GeomStaticMesh node.

This is how the render looks from vray standalone, the lines on the lower part are not straight, this is with the property osd_preserve_map_borders=0

This is with the property osd_preserve_map_borders=1 similar issue but in different place


These are renders from 3ds max, with their openSubdiv modifier

This is the correct render

And this is also from max but with changed setting for the UV smoothing, I guess vray uses something similar because its showing the same issue



I have looked into other threads and probably there is no way to get this right, but maybe it could be implemented in a future release.
I have attached a zip file with the scenes in max and vrscene

[jovcem]

Can somebody confirm that this could not be replicated in Vray Standalone.

[jovcem]

Any alternatives for this issue?

[hermit.crab]

Thank you for the provided scene and excuse the late answer. First of all, there seems to be a difference between the provided 3ds Max file and the exported .vrscene. From what I tested, I couldn't manage to reproduce the differences even with V-Ray NEXT; the issue was only visible with the provided .vrscene. I noticed that when exporting a .vrscene from the 3ds Max file, the "osd_subdiv" parameters are not written in the fresh export (possibly they're manifested differently). What seemed to remove the crooked lines is either setting the "osd_subdiv_level" to 1 or removing all the osd_subdiv and osd_preserve parameters. If this is not satisfactory, do send a matching 3ds max file and .vrscene so we can continue testing.

[jovcem]

Yes, when exporting vrscene from 3ds max it does not write osd_subdiv settings, I added them manually. This is how I got the vrscene:

1. I exported vrscene from 3ds without openSubDiv modifier
2. Added the osd_subdiv parameters manualy

Now I compared that scene with 3ds max scene with openSubDiv modifier.

If I export the scene from max with the openSubdiv modifier and without manually adding the osd parameters in vrscene I get good result.
But that means that the subdivision is baked in the vrscene, and thats what Im trying to avoid, my end goal is to have smaller files.
So far it seems impossible to do, unless you make an update in a future version.

[alexander.kazandzhiev]

Hi

The 3ds Max displacement modifiers are applied directly to the geometry and V-Ray receives the geometry with the displacement applied. It gets written in the .vrscene too. If you would like to use a render time displacement it should be done with VRayDisplacementMod: https://docs.chaosgroup.com/display/...isplacementMod in case you don't want the subdivided geometry in the .vrscene.
I've checked that there are some OpenSubdiv options e.g. "preserve map border" that are not exported and this should be fixed, so I'll make note for this.

Best regards,
Alexander