Hdri and mentalray settings: car lacquer problem

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  07 July 2007
Hdri and mentalray settings: car lacquer problem

Hello again dearest forum,

i have a problem with maya 8.5 and the settings for the hdri and mentalray.
I know that there are no polygon errors on the car, because with other settings there are no artefacts like in the rendering below. In addition to that the hdri image is ok. My problem is, that i can not find the settings effecting these artefacts.

If anyone can help, I'd be most appreciative.

I use the the mi_car_paint_phen shader without Flake_weight, so it should be very smooth.

Thank you
Stefan



Last edited by IIZiPFeLII : 07 July 2007 at 09:08 AM.
 
  07 July 2007
Stefan, that looks to me very much like you got flakes on there.
Try to set every parameter regarding the flakes to zero...

Good Luck - Christoph
 
  07 July 2007
Thanks for fast reply, but every parameter regarding the flakes is set to zero:-(
 
  07 July 2007
That is very odd indeed - this so much looks like the mi car paint flakes...

Do you get the same effect with other shaders?
Tried applying the same material to a new object?
Start the scene from scratch?

Don't know what else this could be...
 
  07 July 2007
hey sixbysixx,

yes, i get the same effect with others shaders and i applyed the same material to a new object as well.

this is the reason why i think that the errors must me a result of wrong mental ray settings.

perhaps i work with a wrong final gather min/max radius setting?

Last edited by IIZiPFeLII : 07 July 2007 at 12:21 PM.
 
  07 July 2007
I have found out that there are no artefacts without additionally light emission.

With Light Emission switched on like this:

Qulity U = 20
Quality V = 20
Samples: 40 / 16
Low Samples: 5 / 2
Vary Focus: 0.800
Disable Black Light
Emit Diffuse
Emite SPecular
Use Ray Trace Shadows
Shadow Color: black
Ray Depth Limit = 2

... there are still the problems.
 
  07 July 2007
Ah - there were some problems with the car paint and IBL light emission, but they looked different and I thought they were fixed with Maya 8.5
Are you using an earlier version of Maya?
The light emission of the MR IBL node is rather crap anyway. I only use it for FG and then add a few additional lights in order to get the metallic effect.
I really hope they rework the whole IBL node soon.
 
  07 July 2007
hey,

no, i do not use an earlier version. I am working with Maya 8.5.
I know the problems in maya 8.0, but these problems really
were fixed.

i am despairing:-(
 
  07 July 2007
First of all, having a flake_exponent of 0 is gonna boost the strength - but it should still be invisible if flake_weight is 0. Hmm...

Set all flake settings back to default- or create a new car_paint_phen and then lower flake_scale to .01 or lower. Tell me what the result is, I'm curious. Hopefully it's more predictable.

-shawn
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  07 July 2007
Hm ... I doubt that your problem has to do with flakes. But if you want flakes not to appear, just leave all flake settings as default and just set flake_scale to zero - flakes are gone.

To me those little round spots look more like your hdr image is a bit noisy. Try to set the filter setting in the Final Gather tab in the render globals to 1 or even to 2.

I am not so sure about these strange triangles. Are the normals on your geometry alright? Do the triangles also appear when rendering without final gather?
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  07 July 2007
Those are flakes, a better question is why they are appearing. The hdri final gather dots just require more samples and maybe up the fg filter. You try my suggestion yet?

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  07 July 2007
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