Hi. New to Houdini, long time Maya/Max/Modo user (looking to replace all of them, hopefully). Please excuse the beginner question, I'm sure I'll even get the terminology wrong.

I've imported an FBX coming from Mudbox that turns out to be much too large (correct size in mudbox) - I had to scale it down to .001 to make it “real size”. My problem is that in my (vray) material, all values also need to be scaled down to almost nothing to not look extreme. My bump values are around 0.001. I tried to “clean” transform, didn't work, then I removed the pre-transforms and parented the geometry to a scaled down null (I read somewhere that that was the way to do it) - didn't work.
I feel like there's something fundamental I'm missing. In Max and Maya you can just freeze transforms, but in Houdini I'm being followed by the scaling and can't seem to do anything about it. How do I fix this? I don't want to scale down the FBX in some other program before import, since i'll be updating the model in mudbox often (then exporting it).

Thanks.

Parenting to a null, or scaling the subnet containing the imported FBX is the right way to go, especially if your imported scene contains many objects.

There's not much you can do to get around needing to scale values that correspond to world space distances. Freezing transforms/removing pre-transform has nothing to do with shading space which takes place in a collapsed space.

Multiplying by a scene scale part of the process of importing assets created for different working scales. It should not be an issue to use small numbers as floating point numbers preserve precision, regardless of how many zeros are after the decimal.

Bump/displacement map values can be used as-is when displacing in object space. The principled shader unfortunately does not expose the control for switching to object space displacement. The control is on the displace along normal node, which can be found buried many levels inside the principled shader. Subsurface values will always need to be multiplied by the scale factor, as there is no object space for subsurface scale.

Thank you for explaining. I'm using vray's own shaders and in every other program V-ray uses object space, but apparently not in Houdini. After reading your answer I found that V-ray has settings for units, I'll try that the next time I'm in Houdini. Thanks again.

But, just so I understand correctly; if I use different models from different sources (sculpts from mudbox, hard surface from modo etc) that exports with different sizes, there is no way in Houdini to make the scales consistent? I will have to use different scales depending on which material/model I'm currently working on?