Bump Strength Question Tweet

[Andreas_Resch]

Hello.

I'm just playing around with bump maps and noticed something. It seems as if the bump strength changes with the size of the object (or amount of 2D transformation). In the image below you can see a closeup of two planes. The left one has a side length of 6cm, the right one 60cm (10 times as much). They both are assigned the same material, except for the 2D Transformation that scales the size of the bump map is adjusted to match the scale. Somehow the bump map is stronger on the larger plane. What could be the reason for that? I also attached the version in Cycles, where the bump strength is the same in both cases (blue material). I've also attached the notes that I used.

[Andreas_Resch]

One more thing. The bump map on the bigger plane also looks way less detailed.

[elsksa]

Hi,

It occurs in, for instance, the mesh-UV/box projections. Changing the "coordinate space" to "World space" will prevent the auto-scaling from happening.

[Andreas_Resch]

Hello.

There are no issue with auto-scaling in the scene. Both object have their scale applied, so they are not seen as "scaled" in the scene. It's about the depth and sharpness differences of the bump map when different values are used in the "Scale" section of the 2D Transformation node.

[EDIT] It seems as if adding a "XYZ to UVW Projection" node solves the issue. I can stick with the "Object Space" there and it looks fine. It's still odd though that the 2D transformation is affected in such a way.

[EDIT 2] Just found out that the "XYZ to UVW Projection" messes up my UV map. So I can't really use that workaround. So it there any other way to solve that?

[Andreas_Resch]

I checked if the issue appears on procedural maps as well and it does. Here's a test with two tile textures. Same texture, different 2D transformations applied. I remember having had the same issue with Luxcore, a few years back. Not sure how that is related but it's quite interesting that both renderers had this issue.

[linograndiotoy]

I just tried here and it looks fine. Any scene to share?

[Andreas_Resch]

Here's a test scene. The larger cube is 10x the size of the smaller one. It uses a Transformation node to get the bump map to the same size as the small one. As you can see, the bump map on the larger cube looks quite different from the smaller one. It's more pronounced and less detailed.

http://www.argfx.at/upload/Octane_BumpTest_01.zip

Here's the same scene but it uses a procedural noise pattern. Same issue.

http://www.argfx.at/upload/Octane_BumpTest_02.zip

[elsksa]

I just tried here and it looks fine. Any scene to share?

The attachment Capture.PNG is no longer available

I believe that's what Andreas meant to showcase.
I'd have to replace the texture file prior to sharing an ORBX.

[Andreas_Resch]

I just posted two scenes in the previous post. I appreciate any tests.

And, yes - if I feed something like a Box Projection or the XYZ to UVW Projection into the image node, it looks fine. Only when I use the scaling alongside an UV map, these issue occur.

[linograndiotoy]

I just tried here and it looks fine. Any scene to share?

Capture.PNG

I believe that's what Andreas meant to showcase.
I'd have to replace the texture file prior to sharing an ORBX.

Anything shared with the team is basically covered by NDA. We would need an ORBX showing the issue so it can be fixed in Standalone.