Bump mapping issues

[vandigital]

I am finding it very hard to get good bump maps in Vray compared to MODO.

Vray often looks flat or like the bump is just wrong. I have to play with gamma and delta forever to get even just a little close to what my MODO versions have. Is there some magic behind this or errors?

Also bump maps in RT CPU do not look the same as in render.

[vladimir.nedev]

Can you attach an example scene or send one to me ( vladimir.nedev [at] chaosgroup [dot] com).

Are you using V-Ray materials with V-Ray or the MODO ones ?
I did a couple of quick tests and the V-Ray and MODO results seem to be very close when using MODO's material.
I tried Cubic and UV map for the bump texture's projection, as well as scaling the bumped object, as well as repeating the UV space.

The V-Ray material will respect the "Bumped normal check" channel from the "V-Ray Light" tab of lights.
I recently changed the default value of that channel to ON, so it matches what V-Ray for Maya does.
Can you try disabling "Bumped normal check" and see if that helps.

Also bump maps in RT CPU do not look the same as in render.

RT CPU and Production rendering use exactly the same code for this. Can you give me a scene for this as well ?

Greetings,
Vladimir Nedev

[vandigital]

Seems all my problems stem from CAD data and the normals associated with them. Because with other scenes made in modo theres no issue really.

You can load up any cad and you will see the network render issues, bump issues and other general weirdness with vray.

[vladimir.nedev]

What format do you use to import the CAD data ? Can you suggest a site where I can download some example files ?

I think the most common issues with geometry is overlapping faces. Can you try running a mesh clean-up command on the geometry and see if that helps.

When overlapping faces are present, the Embree library might build a different acceleration tree on different machines (based on thread scheduling), which results in different buckets.

Greetings,
Vladimir Nedev

[vandigital]

Ya I will try and set aside some time to get you a scene today. With examples from modo to vray.

You can't perform an operation like that or else you destroy surface normals and it will never render correct if you do that. You have to be sure you dont break them so if you move an object in poly mode you will break normals, has to be item level.

[vandigital]

Tried your above suggestion. Slave crashed.

[vladimir.nedev]

Please send me a scene, that's the only way I can possibly fix it.

Greetings,
Vladimir Nedev