Good morning, all.
So I have to do some instructing on Rhino 8, including a lesson on Rendering.
Back when it was Rhino 6 and Rhino 7, the rendering seemed to work fine. However, now that we’ve migrated to Rhino 8, I’m noticing a bug in the program when doing bump mapping. Specifically, applying a leather bump map to a silver material yields what appears to be… a darkened gray material with some extremely black bumps.
I’m using the following version:
Version 8 SR30
(8.30.26103.11001, 2026-04-13)
Educational Lab License
On this version, applying a bump map to a material creates this anomaly where the material is not rendered with the bump map; it’s almost as if the bump map overtakes the model.
I did this experiment in Raytraced Mode:
Here’s the main model (a sphere on the Studio environment with a porcelain ground).
If I apply a Bump map using the “Bump/Normal and Displacement Map” to this, it does the following (notice that the Bump is set to only 1 %) :
If I raise the value to 100, it doesn’t seem to make a significant change; there is still a bump map, but what happened to my nice polished material on the bump map? It seems to be completely replaced. Here’s the bump map at 100:
It seems all subtlety is lost regarding bump mapping. Compare this to the same values but now on just Rendered Mode:
Rendered Mode (not Raytraced) correctly and very slightly bumps out the bump map at 1% value.
Here’s the bump map at 100%.
As you can see, the bump map accurately renders in Rendered Mode, but there’s something making it not render correctly, in Raytraced Mode.
I have devised a solution that can help get the Rendered Mode visuals in Raytraced mode. It seems there’s some kind of bug in the programming with the strength of the value for bump mapping.
Notice that the material was set to “Physically Based”. We’re going to have to switch the type of material to “Custom” in order to get access to some extra values which, I think, are not being handled correctly by the rendering code, and are being multiplied too extremely.
Here are the new settings for the base material (Polished Silver) :
So what I’m going to do is, I’m going to clear the “Leather Grain Bump Texture” off of the Bump/Normal map. And, instead, I’m going to use “more types” option under Bump/Normal mapping, and then click on the “Bitmap Texture” button on the top, the one next to the Import folder icon:
And I’m going to migrate through the Windows User folder structure until I get to the same leather bump texture source (C:\Users\USERNAME_GOES_HERE\AppData\Roaming\McNeel\Rhinoceros\8.0\Localization\en-US\Render Content\Textures\). I’m going to pick “Leather grey_200_DB.jpg”. It is the same leather as the one used for the leather grain texure:
This is how the bitmap loads by default, with a repeat of 1. We’ll be changing that but I wanted to show it.
If I set it to 5 it’s closer to what the Leather Grain looks like. Nevermind that the mapping is different. We’re just trying to end up with a result that looks like the Rendered Mode, but in Raytraced. We can tweak that later.
So yes, let’s set the “Repeat” value to 5 (it is originally 1). We will also set the mapping to WCS/OCS (box style). Now we have this:
As you can see… it still doesn’t look like Silver. It looks like a hard black ruggedness has taken over the material.
However, this is where setting the material to Custom, and setting the material to Bitmap, can help us… because with these values we have access to some settings which I believe are the result of the bug. It seems the bump is being multiplied too strongly so it’s completely taking over the material, even when you set the bump to 1. So… let’s mess with the MULTIPLIER at the bottom of this screen. Go down to “Color Adjustment” and you will see that the Multiplier, Gain, Saturation, and Gamma all have a value of 1.00.
The key here is to change the multiplier to a very small value.
We’re going to set it to 0.0001 and then back back out. Now we can see the bump a little closer to the rendered mode. Here it is at 1 percent:
And here it is, at 100 percent Bump Map:
I firmly believe that something like a decimal value was altered between Rhino 7 and Rhino 8 that’s messed with the bump settings.
If anyone’s had this issue, feel free to chime in. I just updated my Rhino yesterday but this has been an issue since basically Rhino 8 for me. Rhino 7 did a better job with bump maps, it seems…