Bump converter issue with 3D procedural maps

[romullus]

Corona 4 final

Bump converter works incorrectly with 3D procedural maps set to either object XYZ or world XYZ coordinates. As if it requires UV coordinates to render 3D maps. Attaching examples of procedural map plugged into bump directly and through bump converter.

[pokoy]

Good catch, I saw something similar a few times but wasn't sure if it's just a case of 'that's how it is'...

[maru]

As if it requires UV coordinates to render 3D maps

It does.

Note: the CoronaBumpConverter relies on UVW mapping, so if an object does not use UVW maps, or if they are incorrect, it may produce artifacts, or may not work at all.

Sauce: https://coronarenderer.freshdesk.com/support/solutions/articles/12000039641

[romullus]

I see, so it's probably not a bug, but rather limitation? Well, at least now i know.

[Juraj]

Whoa, good I read this in time. I was also wondering why my BumpConverted Noise Maps (WorldXYZ) suddenly look only correct on half the objects in scene, I only recently upgraded those materials to BumpConverter as the result from procedurals is superior but...this is big trouble.

So is it necessary technical limitation ? Maybe it should come with warning or something. Can this be improved ?

[maru]

Moved to feature requests. Let's see what happens next. :)

[romullus]

Let's see what happens next. :)

Let me guess, it will be moved to resolved feature requests board? :]

[maru]

@Romullus: as far as I understand this happens if the object actually DOES have correct UVW mapping, right? So for example, you have some custom geometry with planar UVW mapping so that some diffuse texture is mapped correctly, and then you apply a procedural map to create bump. In such case the diffuse texture will be applied correctly (e.g. a bitmap based on planar mapping), but the bump will be incorrect? Is this pretty much what happened to you?

I found out that the Bump Converter actually produces better results with procedural maps when there is no UVW mapping (e.g. if you put "UVW Mapping Clear" modifier on top of your stack). Maybe this could be a valid workaround?

[romullus]

Object has UVW mapping, yes, but it is pretty messy (i guess that's what makes those issues). Unfortunatelly i can't remove UV coordinates, as it's needed for other channels and fixing them is pretty much impossible. I wonder if it would work if i'd set map channel to something that has no set UVs, would that work?

[maru]

Yes, but as you can see in my screenshots the map channel for my noise map is greyed out. I have no idea why, maybe some procedural maps can only be set to channel 1???
You could instead set all other maps' channels to other than 1, but I can imagine it could be a lot of work.
Maybe the bump converter could have a switch to either consider UVWs (useful for bitmap textures) or ignore them (useful for procedurals like here). I will report this in our internal tracker anyway, because clearly there are some issues here, or at least some confusion.

(internal id=364151177)

[romullus]

Ah yes, that's logical, 3D procedurals does not need UVs, so map channel is unaccesible. I'll try your suggested workaround with moving Uvs to another channel and clearing channel 1. Thanks!

[maru]

Ah yes, that's logical, 3D procedurals does not need UVs, so map channel is unaccesible. I'll try your suggested workaround with moving Uvs to another channel and clearing channel 1. Thanks!

Let me know if it helped. It could be actually useful for other users.

[romullus]

Sorry, didn't have time to test that yet. I'll try not forget to do that and will share my experience.