Inverting bump

[MANUEL_MOUSIOL]

I have to create a shader for this paint/foil called Duropal (in Germany at least) and I thought I would just slap a berconnoise in the bump map. It turns out it is harder to get the right pattern than I thought.
I found some somewhat close vrscans but the bump goes into the wrong direction to get this look (bump goes out and not in with the vrscans).
Is there a way to invert the bump? if not, can it be coded on your side, please?

[Ivaylo Katev]

well, i did a fast experiment, but i'm not very happy with the result, perhaps i recognize the material as leather and see it still with the usual bump.

[MANUEL_MOUSIOL]

Yeah, this looks like it is just lit from a different direction. Like normals are inverted

[kosso_olli]

Yeah, this looks like it is just lit from a different direction. Like normals are inverted

Well, is this not what you asked for in the first post?

[MANUEL_MOUSIOL]

This is actually a confusing picture. When looking at it at a glance, it looks like the bump is inverted alright. Take it into Photoshop, switch between the two pictures and you will see that the leather still doesnt look like its debossed, it is still embossed but highlights and shadows are in different places. You get that when your normal maps colors are switched.
So this is not what I asked for. I want those debossed lines to be emboss and the bulky emboss parts to be debossed when inverting the bump. Like when you give the bump in the vray material a negative value.

[Ivaylo Katev]

Single image is not enough to recognize the real height/normal map , but if the material is known, you assume the correct normal map, and in your eyes it looks like you can recognize it.
But in animation the ambiguos interpretation disappears and the eye recognizes the correct heights.Can you tell me the name of the material that you want to invert?

[MANUEL_MOUSIOL]

You might be right.
let's test it out
Paint_blue_grain_matte_s and paint_0001.vrscan
Thanks!

[Ivaylo Katev]

paint_0001 has a good chance, but i will try this monday

[MANUEL_MOUSIOL]

is it a very complicated matter?
could this feature be implemented in the UI?

[Ivaylo Katev]

Let first see if it's useable at all

[Ivaylo Katev]

the original paint0001
https://vimeo.com/345216294
the inverted paint0001
https://vimeo.com/345216459

[MANUEL_MOUSIOL]

Looking good, don't you think? Thanks for the video for easily understanding.

[Ivaylo Katev]

Yes, i think there are no major issues. Unfortunately not all the materials can be inverted, only the ones created by specific pipeline. Perhaps you have noticed that the material that i inverted (paint0001) is significantly smaller than the other one (Paint_blue_grain_matte_s). The reason is the lack of side views in the smaller material, it's using height map and paralax to represent proper behavior for shallow observation angles. This technology is the dominant one in the last two years, it has two major advantages - the lower size and the sharper result (because all the images blended in the rendering have equal size). Of course not all materials can be represented in this way, but fortunately the big majority can, and now we use the full scan only in rare cases when the material has special features. So, this feature (the h-map inversion) can't be implemented as render switch, it modifies the material, not the rendering. Currently i did it using the software that builds the materials, but is's only for internal use, so i will prepare a separate tool that does the transformation.

[MANUEL_MOUSIOL]

I see. But couldn't you implement the switch only on the condition of the proper scan process? You would probably have to tag all the materials though.
but it would definitely make things easier than using a separate to make a new inverted material (which would also take up space as ever inverted one would have to be saved separately...)
or is it generally not possible to do it in-engine?

[Ivaylo Katev]

The reason to chose this way is not because not all the materials can be inverted, it's easy to detect the condition and disable the switch. Considering all the possibilities, i just found this way better, there are multiple reasons, the rendering speed - in the shader would be slower, the robustness - the shader implementation would be bug prone, and of course to not force the users to update or to use nightlies.