realistic car paint method from the Guide

Hi,

I am currently trying to integrate a CG car into a scene and want to
apply the method that Stu explains in the cars section of Chapter 4 in the Guide (only contained on the DVD) to get a realistic car paint look. It seems to be a great method to render out different passes in the 3D application and to combine them in After Effects.

The "Multi-Pass!" paragraph explains which render passes are
needed from the 3D-app and then gives a detailed explanation of how to control the reflections of the car paint with the levels effect. I am missing some explanation of the entire setup, namely

- in which order to compose the layers of the different render passes ?
- what blending modes and/or track mattes ?
- which layer should the levels effect be applied to ?

I am really wondering why this crucial info is missing while all other parts of the approach are perfectly explained in detail. It almost seems as if some paragraphs got accidentally lost.

I am guessing the following setup:

- diffuse layer with blending mode "normal"
- on top of it the specular layer with blending more "add" and track matte "luma" (or luma inverted)
- on top of that the normal/fresnel layer (invisible, used as track matte) with the levels effect applied to it

Any better suggestions?

Best regards,
Mathias

Dont know the answer specifically, but this might help?

http://www.cgsutra.com/adobe_after_effects_tutorials/render_passes/compositing_render_passes_after_effects.php

Thanks for the hint! The tutorial uses different kinds of render passes than described in the book, but probably there are many ways to do it. I think it depends a lot on the scene.

My scene currently looks as follows.

Here is the video.

There are still several things to improve. Any suggestions are welcome.

Mathias -

Thank you for posting this. I think it's a good start, but there are a number of things that are not yet working.

The Porsche has no shadow, and the reflections look wrong as well. There's a giant white sky and I don't see any of it on the surface of the car. I do see the reflection of foliage which seems to have no relationship to the fields that surround the car. Also, the perspective seems wrong.

Next, the fields and road are obviously texture maps. It's all too even and it's easy to see the pattern of repeats. Make bigger maps! Mess them up more. Also, it appears that the road is half a road that's been mirrored, so any imperfections on one side are repeated on the other. These are all giveaways that you've done this in the computer. Again - mess it up more! The real world should be your guide. Right now the whole thing looks like a matte painting from The Wizard of Oz, only without Munchkins. Smile

Finally, the police car. This is working the best for me, but it suffers from the same problem that everything else does. It's too clean! Cars don't look this good fresh from the factory! What you want is a grunge pass as part of your multipass render sandwich. Also I'd like to see a shadow and/or a reflection interaction with your actor - even if it's subtle. The edges seem a bit sharp. Perhaps you could soften them a bit. Maybe add a bit of video grain. And the green - particularly on the hood - feels too bright.

But I really think your first step should be to get your digital camera and go out and study how things look in the real world. How cars look when they've been washed and waxed a bunch of times and have thousands of infinitesimal scratches and a little dust - even when they're "clean." Look at some fields. Roads are never completely clean - there are oil stains and roadkill and cigarette butts and random cracks and bits of grass and so on. Perfection is a giveaway that we are not looking at reality, and the only way to get really good at duplicating reality in the computer is to become a student of how the real world actually looks, something you can't do in front of your monitor.

Hope this helps.

Arthur

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Thank you for these detailed comments!

I will definitely add a shadow for the Porsche and try to improve the reflection. So far the reflection consists only of a layer of clouds that I generated with After Effects Fractal Noise Effect. I am not sure whether I am able to improve the perspective since the Porsche is no 3D model.In principle I had to re-shoot the Porsche with a camera-movement that is in sync with the After Effects camera but I have no idea how to get a smooth upwards move (I have no crane or something similar and matching the movement by hand was already a pain when I did it for the guy in front of the police car).

I will try to improve my textures too. I hesitate a little to enlarge my textures since the fields consist of several hundred After Effects layers and the final render took about 24 hours.

For the car I in fact already have a kind of grunge pass, but I guess it should be a little more opaque.

Your comments are really a great help. As soon as I change something and find the time to render it, I will post the new version.

Mathias

Hey guys,

You appear to be correct mmohl, there seems to be something missing from the PDF. Let me see if I can help here.

You use the frontlit plastic render as a track matte for the chrome render. Then dial in the Levels effect on the top layer as described in the PDF.

Does that help? Sorry again for the omission.

-Stu

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