AO bug/error

[Gruender]

Hi,

does anybody now how to get rid off those artifacts?

And include/exclude lists seem to be reversed.

Cheers ...

[Eddoron]

A bit hard to see.
My first impulse would be to crank up the samples.

[Gruender]

I pushed up the samples to over 100 and the effect didn't change.

[Eddoron]

Could you tell/show us what exactly it is, maybe show the geometry and material settings? There must be a way to fix it.

[Gruender]

Nothing fancy...

[Beanzvision]

Phong tag?

[iacdxb]

I tried a old file and AO is working fine.

Can you drop your and what you want to achieve....?

Thanks.

[Gruender]

Phong tag has no limitation, this effect happens with low or high poly count and seems „show“ every single polygon. 
I wanna achieve a smooth transition in the shown area for heated metal reflection.

[iacdxb]

You mean like this tempered metal... attached....?

Many ways, I think best is make UV and make texture and apply.
OR... try with some multi color gradient and some scratches texture.

...

[Gruender]

Thx for that hint, I know different ways to achieve it, but I am curious how to avoid those artifacts.
That is why the topic is AO and not temperate metal on weldings.
Maybe someone from the developement team can lift the curtain.

Cheers...

[Eddoron]

I was able to replicate the effect. I tried the object with the basic UVs and cleaned up UVs. It's pretty much the same.
My conclusion is that it's highly scale dependent and sampling doesn't do much, even at max values.
The sampling areas are not properly "connected"/smoothed into each other. I, as a non-programmer, see this as an interpolation problem.
Color spreading can make it a lot better but it can go off rails into unwanted areas and at some more distant AO'd areas, the artifacts still appear.
Spreading is not the same as smoothing, so there might be an option that is missing. Sampling is afaik just affecting the accuracy.

There sure are a lot of workarounds for that, though baking AO gave me the best results, even with the standard c4d baker.(btw you can convert the AO bake into a vertex map and it might be more flexible than a bitmap.)

A curvature shader should be best for that task.(hope we get one)

[houska]

Hey guys! Just wanted to chime in before we find some time for this report!

It seems to me that this problem might be connected to geometry, so anything from incorrect normals and badly created geometry to Corona not interpreting valid geometry in a correct way. If I were you, I'd try to play with the phong tag settings or remove it altogether.

[Gruender]

I tried different settings in phong tag, but that doesn't have any effect.
Furhter more I checked vertex normals and everything looked fine. Every other render effect (fresnel, mapping, bump) looks alright, so I don't think it is because of bad geometry.
It looks like every poly is handled seperately.

But thx for your reply anyway!

Cheers

[Eddoron]

Hey guys! Just wanted to chime in before we find some time for this report!

It seems to me that this problem might be connected to geometry, so anything from incorrect normals and badly created geometry to Corona not interpreting valid geometry in a correct way. If I were you, I'd try to play with the phong tag settings or remove it altogether.

I had the same effect with clean subD modeled geometry. Phong tag didn't change anything.

[houska]

Can we see a scene, guys? I tried it and everything looks fine to me (don't mind the weird geometry on the caps...)