Author Topic: UVW Randomizer Issue  (Read 1194 times)

2022-09-25, 14:11:35

dj_buckley

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See screenshot.  These 3 objects (close up of banquet seating) have the exact same material on them, except the furthermost left one.  The only difference with that one, is the jpeg used for maps are also plugged into UVW Randomizers.

It looks to me as if the normal map is being inverted when plugged through the UVW Randomizer.  Which in turn is making it "shinier".  I've no idea if thats because of the inverted normal map or if it's also inverting any of the other maps i.e. bump, gloss etc.

Max 2021 Corona 8 HF1

2022-09-25, 19:28:37
Reply #1

romullus

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Could it be that you plugged randomizer in incorrect order? AFAIK, its correct position is between normal texture and Corona normal node. It also could be a mismatch between different maps. Double check if every randomizer is absolutely the same, including random seed parameter.
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2022-09-25, 20:14:56
Reply #2

dj_buckley

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I've checked all that, but I'll check again.  As for the correct order, I'll screenshot the shader and post it shortly.

2022-09-25, 20:39:02
Reply #3

dj_buckley

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Shader tree attached for both materials.  As you can see there is a UVW Randomizer for the 'smudges' on both materials.  Other than that, all I've done is add additional UVW Randomizers for the other maps.

All UVW Randomizers have the exact same settings.

Top material is the furthest left object, bottom material is the 2 objects on the right.


2022-09-25, 21:28:14
Reply #4

romullus

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You need to swap places trilanar with randomizer. Correct order is uvwrandomizer->triplanar->material. But i'm not sure if that's the cause of the issue, because that mistake is in both materials. Other than that, everything looks correct.
I'm not Corona Team member. Everything i say, is my personal opinion only.
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2022-09-25, 21:42:04
Reply #5

dj_buckley

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To be honest I could get rid of that smudges layer.  In the composite, the layer opacity is set to '10' so it's definitely not that, but good to know it's in the wrong order.

2022-09-25, 21:43:44
Reply #6

Basshunter

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You need to swap places trilanar with randomizer. Correct order is uvwrandomizer->triplanar->material. But i'm not sure if that's the cause of the issue, because that mistake is in both materials. Other than that, everything looks correct.

Is there any info about this in the Corona documentation? I've been having similar problems when not connecting maps in the right order.

On the other hand I wish it was possible to connect these maps in any order without this being a problem.

Also, as mentioned in other posts, it would be great if we could connect a single ranomizer/triplanar map for all textures instead of needing one for each map. Just like in Vray.

2022-09-25, 22:19:44
Reply #7

dj_buckley

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This article has a very brief reference to the 'order' but only in relation to the triplanar map.  All of the other examples in the article show the randomiser used at the end of the flow, so it is quite confusing https://support.chaos.com/hc/en-us/articles/4957371864977--Corona-Uvw-Randomizer-Map-3ds-Max


2022-09-26, 00:20:38
Reply #8

Basshunter

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This article has a very brief reference to the 'order' but only in relation to the triplanar map.  All of the other examples in the article show the randomiser used at the end of the flow, so it is quite confusing https://support.chaos.com/hc/en-us/articles/4957371864977--Corona-Uvw-Randomizer-Map-3ds-Max

Yeah, quite confusing :c

2022-09-26, 10:09:52
Reply #9

romullus

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It's the triplanar that requires certain wiring order in order to work correctly. UvwRandomizer can be basically in any position you need.

Also, as mentioned in other posts, it would be great if we could connect a single ranomizer/triplanar map for all textures instead of needing one for each map. Just like in Vray.

AFAIK it has been requested many times and it's logged in the support system. I'm pretty sure that sooner rather than later we will have it.
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2022-09-26, 12:04:47
Reply #10

dj_buckley

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Just running some tests with random normal maps.  It seems related to the W Rotation of the UVW randomizer (either that, or i'm not understanding something about how normal maps work).

2 screenshots attached.  Only difference between them is the one that looks 'inverted' has the W Rotation 'To' value, set to 360.

The normal map is taken from Poliigon https://www.poliigon.com/texture/penny-round-tile-texture-sea-mist-hexagons/7327

Edit: Now that I look at it on this example, it seems it's just the light changing direction as the normal map rotates, noticeable on the distant spheres, a downside to normal maps perhaps, an optical illusion??
« Last Edit: 2022-09-26, 12:09:42 by dj_buckley »

2022-09-26, 12:20:08
Reply #11

romullus

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That's correct, when you're rotating normal map, it's the same as if you'd rotate mesh normals themselves. No doubt this will give you all sorts of weird illusions. It is best to leave W rotation alone and stick to U, V randomization only when normal maps are involved.
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2022-09-26, 15:45:10
Reply #12

aaouviz

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That's correct, when you're rotating normal map, it's the same as if you'd rotate mesh normals themselves. No doubt this will give you all sorts of weird illusions. It is best to leave W rotation alone and stick to U, V randomization only when normal maps are involved.

Wow, this is kinda mind-blowing to me. Obvious now that I think about it, but it shows I've been doing things very wrong ever since the UVW randomizer came around.

So what I'm understanding from this is that there isn't actually a way to truly randomize the textures in a traditional format? If I have a diffuse map that matches the normal (ie; wood grain) I can't go and randomize the diffuse W value as this means I'd also have to randomize the normal map W, which results in wrong normals?

I'd either have to revert to bump (greyscale) maps OR not randomise, OR only randomize non-critical elements (such as smudges)?
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2022-09-26, 16:36:44
Reply #13

romullus

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For starters you wouldn't want to randomize rotation of the wood texture regardless of presence or absence of normal map. It's highly directional texture and would look weird if it would be oriented randomly. Anyway, i don't see that as a problem - i use randomizer a lot and i almost never rotate the textures, even if they are simple black and white grunge masks. I find that simple U and V shifting is giving me enough randomization and there's rarely a need to use rotation.
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2022-09-26, 16:40:18
Reply #14

dj_buckley

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I often randomise the rotation of wood but with a Step value of 180.