Bump incorrect behaviour Tweet

[doca]

Hello Octaners,
After some time trying to implement Octane in our studio as much as possible as main render engine, I am finding some frustrating things. For most of them, we found workarounds, but one of them that is most frustrating is the way bump works. Octane has beautifully sampled bump, but some serious problems comes after that.
As first, I can not understand if there is zero/mid/water lever for bump? There is no way to keep bump intensity but to offset it's middle level. It is very problematic when you want to mix textures to achieve some effects and even more problematic when you want to mix materials.
To explain what I mean, here are some screenshots with explanations:

lets say I do have two materials with different bumps that I want to mix:

If I do common mix materials with some blending map, I got this result:

In some way, result is ok, bump are blended by texture, just as materials are. But, as you see, bumps are the same level and what If I want to offset zero level of one bump, to achieve some layer effect, like, lets say, painted material over some other? By that I mean this effect:

There is no way to achieve correct result. For this example I mixed bump maps and plugged that mix in both materials, but it can be noticed that whiter material almost lost bump and this way of mixing bump maps is even more pointless if you you further mix materials with more layers.
Currently, as I understand it, bump is controlled by multiplying texture, or through texture intensity, so, by that, there is no zero/mid level for bump, but bump is multiplied/stretched from black color, so middle level for bump is floating. That is obviously not good, correct or user friendly for complex multi layer materials. I posted just one.
So, establishing zero/mid level for bump maps is something essential that render engine has to have.
To further explain complexity of the problem, here is simple example. One bump map, one material. Just in one case I remapped texture by gradient node to range from 0 to 0.5, and in another case I remaped texture to values from 0.5 to1. In normal bump behaviors where bump would have water level on 0.5 color value, those bumps should look the same visually, until we mix two materials with every have one of these remapped bumps. Here is remapped bump compared:

It is obvious that this is not correct.
I do have few suggestions for this problem. One is to have separate bump node with zero level control just like displacement node have, or to have sliders in mix material node for bump zero/mid level for each material, like this:.

Maybe it is not so nice to post how competitor is solving this, but here is an example how Redshift bump node looks:

redshiftBumpNode.jpg (31.08 KiB) Viewed 1365 times

Maybe there is too much controls there, and if you ask me, adding zero level slider for bump somewhere is enough, but having that control is essential.
This is a huge problem and I am really confused how it was not asked/solved earlier.

Best,
Doca

[roeland]

You can put other texture nodes between your bump map and the bump input on the material input. For instance, try bump texture → clamp → bump input on material. If you have separate bump maps for the paint, the substrate and the edges of the paint, you can add them together.

For instance here's a rough setup using procedural textures for the bump maps:

Paint.orbx

(142.6 KiB) Downloaded 123 times

Roeland

[doca]

Thank you Roeland, that is a really cool tip!!!
But, I must say that becomes not so user friendly with little more complex shading networks. For example when you have to mix other two material mixes like this:

Talking, of course, about case where all the materials have bump maps.
And what about even this extreme case:

Your approach is very clever, but in those cases that can be very common in production, it starts to be very messy and hard to follow.
From my point of view, with bump mid level slider in mix material node, all the problems will be solved, without any hacking and that way it will avoid returning back to tweak all the bumps up on shading tree.
Best,
Doca