fake stone artifacts

Started by Dune, September 24, 2014, 06:41:06 AM

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Dune

Any idea why this can happen?

Kadri


Interesting.Haven't seen that kind of error.
Does it happen all the time when you render it Ulco?
I mean when you render it ones more is it the same?

Maybe an Alpha issue?

Dune

It renders the same all the time. I'll probably put it up at alpha as well....

Oshyan

Have you used the Check Animation button or changed any of the Subdiv settings?

- Oshyan

Dune

#4
Nope, I'll try that.

Edit: then it's even worse (with animation checked and adopted). By the way; there's no turning back once the animation check has changed stuff, is there? Unless you use undo right away, of course.

Dune

I think it has to do with a rather unorthodox way of blowing up stones by an added displacement shader fed by color. By the way, what is 'Exception caught in juRenderNode::FinishRender Render 01'?

j meyer

I've had that effect when playing with voronoi bubbles and had
another way of adding displacement,so may be it's something
else.Reminds me of some results you can have when working with
hard contrast and high variation values in a PF. Somehow at least.
Not of much help,sorry.

Oshyan

It seems like you're just trying to displace a surface too much; you're going from a very small area (pre-displacement) to a much larger area and the renderer has a limit on how much it will subdivide the geometry (for performance reasons, to avoid runaway render times on rendering extreme displacement, etc.). The limit is reasonably high and most of the time it's not an issue, but it does seem to show up on stone displacements more often, possibly because they're at such small scales and being displaced more heavily often-times. So your intuition was more or less correct, and the solution would be to reduce the disparity between pre-displacement and post-displacement scales (so to speak), if possible. I hope that's clear (and accurate) enough.

- Oshyan

Dune

In fact, that is entirely what I thought after thinking about it. Strange thing is that it doesn't affect all blown up stones, but that may have to do with the 'size of the origin and fractals afterwards'. Or something. I did add a XYZ node after it for additional smallscale displacement, but that is apparently not enough for a new calculation. Nor is a compute terrain/normal with small patch. I'll keep this restriction in mind, thanks Oshyan.

fleetwood

#9
I've had a similar thing when using stacking of positive displacement offsets. I was just guessing it had to do with the displacement exceeding the polygon level of the surface in those areas so I backed off on the offsets.

Example :

Dune

Yeah, it seems we have to take care with those blowups  ;)