Rhino 8 Mac raytracing acting strangely when applying bump

[Dobey]

As I moved from Rhino 7 to 8 I noticed that when applying a bump it looks off as if there was too much contrast when being raytraced, despite the ‘rendered’ view looking good. I have tried tweaking various values with different models.

[Japhy]

Hi Dobey

Here is a helpful thread. Bump textures not rendering at all - #2 by nathanletwory

Note that there is bug we are tracking as well Bump textures not rendering at all - #2 by nathanletwory

[Dobey]

@Japhy

Bump textures not rendering at all - #2 by nathanletwory

Thanks that thread did help ( in my case the value had to be lower than 1 for the bumpstrengthfactor)

[encephalon]

@Dobey

As I moved from Rhino 7 to 8 I noticed that when applying a bump it looks off as if there was too much contrast when being raytraced

bump is actually broken entirely for a long time now. try changing the intensity percentage. i would be surprised if you see much of a difference.

Bumpy Bump?

hi @nathanletwory i remember having to set RhinoCycles.BumpStrengthFactor to something much higher for this to work in v8 now the bump does not change at all, setting between bump 1 and hundred in the regular bump setting makes almost zero difference beside some slight different shading effects and tweeking RhinoCycles.BumpStrengthFactor makes also close to zero difference. [Screenshot 2025-08-17 at 18.46.29] above set to Value 100 [Screenshot 2025-08-17 at 18.47.10] this one is set to Val…

[hitenter]

I didn’t need to do any rendering since quite some time. Last time was when RH8 was just released. I did rely a lot on materials that use bump mapping. I recently opened the files from that project again because I wanted to quickly test the render performance of my new 5080 and noticed right away that the objects looked very strange - very much like shown in the upper right of the four viewport screenshots here in the first post.

I think this is unacceptable. Bump mapping isn’t some niche feature, it is very basic and all renderers make use of it. The user should be able to reopen his work and achieve the same render results every time - obviously. It took weeks of tinkering to get a certain look from the renderer/cycles, now this is all totally gone.
Luckily I don’t need to do rendering currently, for now I just wanted to have a quick look at the performance. However come January/February, I will need to pic this work up again and I do need to be able to reproduce the exact same render results.
I think we can expect this to be fixed asap - I’m really baffled about why something like this isn’t addressed with a quick hotfix release as soon as it is noticed.
I have no problems when bugs or changes that cause the renderings to look different happen when moving to a new Rhino version or during the WIP phase but surely not within the life cycle of one release version.