Audi Q7 - first render

[TopNub]

In 2008, when I was newbe in modeling and rendering in 3d's max (it was the V-Ray) my best model was the Audi Q7.

Now, after several years of experience I returned to this model for get expirence in nuke and rendering in Houdini.

Now the results of such:

http://funkyimg.com/viewer.php?img=/2/1228/453/969753audiq7_front_04_finpaint.jpg

I downloaded the shader here - http://forums.odforce.net/index.php?showtopic=406&hl= and I have with him the following issues:

1. Why is this shader does not work with a PBR?

2. Why is the paint gets noisy, even if I remove the flakes of the shader and do a lot of samples in Environment Light? If I put GI Light, the noise is too, but slightly smaller. What the secret of this shader?

Until that day I did just fx in Houdini, please help.

Edited January 22, 2012 by TopNub

[LaidlawFX]

Different noises require different adjustments, but I'm guessing if you are using pbr that is reflection noise on the shader, and you need to turn up reflection quality. This might be do to reflection blure that you turned up. Secondly I would turn up the max ray reflection to 24 or 32 and the min ray reflection to say 2 or 4, This last one will make a significant hit in render time.

A fourth option is to turn down the color limit to say 4, or lower if you can. You will notice if it is a problem withthis, if those specs are of extra-ordinary high values compared to the surrounding pixels. Which may be caused by using an env map to high, or a non-pbr style shader.

If you think it may just be PBR test the shader on a simple default sphere, and remove all the other possible factors. It should just work with PBR, and that type of issue should have disappeared with h10, but the setting in houdini need to be more intuitive.

[Erik_JE]

The shader is from 2002 (old) and probably don't have the necessary BSDF setup for PBR rendering to work.

[LaidlawFX]

Time for an update!

[Erik_JE]

I have some attempt I made at a car paint shader somewhere. I'll see if i can find it.

[LaidlawFX]

The standard mantra surface should get you pretty far. It has all the default PBR stuff working within the surface model.It also has the two layers of reflections you'll need from the car paint(check the help docs for the parameter usage, they have changed up their names from what you might have had prior to h11). and some pretty good fresnel action already(not as intuitive, but it gets the job done). You will have to add the paint specs, but that should be a pretty easy noise layering into the diffuse color and/or base spec layer. I would just look at the control interface of your older shader, as the noise patterns are probably the same, and just go for a mult into color, and see how far that works, then add the paint flex into your spec patterns.

[TopNub]

Thanks for the tips!

I used regular mantrasurface shader, turned in his strongest cover reflection and normal reflection at 0.3. Added chrome and glass. I paint and chrome I have included physical Fresnel.

Strangely, I almost did not do anything, but it is similar to the paint or not?

References:

http://wallpaperstock.net/audi-q7-white_wallpapers_5421_1280x1024_1.html

http://upload.wikimedia.org/wikipedia/commons/8/87/Audi_Q7_TDI_5165_DC_03_2009.jpgThanks for the tips

[LaidlawFX]

I think your asking if the chrome is too close to the paint? One of the things that separated the chrome from paint is the environment for its reflection. For chrome you really need to have a good studio light hdri, or hdr with a lot of white in it to drive the highlights, the base color should be very weak in chrome compared to paint. And paint really needs to have the two reflection layers to make it look correctly. Also for chrome play around a bunch with the fresnel, you may have it technically correct, but you may need to dirty it up with some noise, to make it look "real." Mantra's default are sadly not like Vrays for hard surface so you need to play with it a lot. TO get the material to appear different.

[stu]

You might want to remove the fresnel calculation from the chrome's reflection contribution - it's just about equally reflective regardless as to which direction the faces are pointing in reference to the viewer.