Hey,
If I take an object with bump, scale it by 500%, the bump disappears. Vice versa, if I make it smaller, the bump increases. It seems that bump is calculated in world space. Can it be changed to local space, so scale changes don’t affect bump?
Cheers,
Nick D
I think you mean that the bump is not affected by the object scale 
In other words you want it to scale with the object which is not the way it should work.
Bump just like displacement is actual units. Whats white in bump/displace, and with the multiplier set to 1, will be 1 cm in units (if thats what maya prefs is set to). So a multiplier of 0.1 will be 1 mm, etc.
If you convert your bump map to a normal im pretty sure it wont be affected by the scale of the object, but rather just the strenght of the actual normal map (combined with the multiplier again). So then you can scale your object 500 times, and the appearance of the “bump” will be the same.
I think you mean that the bump is not affected by the object scale In other words you want it to scale with the object which is not the way it should work.
Well, this isn’t how Arnold works. Bump and Displacement are all in local space there; so there isn’t a right or wrong way to approach this, just preferences. The advantage of having an option to get bump/disp in local space is that it frees layout to scale objects as they wish, without having to have x number of versions of an asset. It’s more flexible.
V-Ray actually supports that, but it’s not exposed in the UI (that’s how bump works in 3ds Max, so we’ve had to support both modes). I will make a note to add the local bump mode to the drop-down for bump/normal map type.
Best regards,
Vlado
We just enriched VRay and VRayBump materials with a new bump option called “Local space bump map”.
Please check it out using one of the latest nightlies and let us know if it works for you or not.