2012-05-08

Simple lighting that always works!

I've had many people ask me how do I create lighting that works for every scene.  If you're using indirect illumination or light bouncing, the answer is: there is no lighting that works for every scene.  I will show you a technique that doesn't use indirect illumination, by creating a simple lighting setup that will always work, and renders really fast.  So this setup is really a cheat.  But it can really work to get a project out if your production time is crazy short.  

 Rendering with this technique


This is a trick that I learned from a friend several years ago, and I'm finally coming around to posting about it.  This is also a trick that adds the Ambient/Reflective Occlusion map to your rendering (I also have alot of people ask me how to add AO to a render).  Basically the idea is that you plug the AO map into an omni light, and the occlusion gets added to all of the geometry in the scene.




This trick is done using 1 omni light, and it is the only time that you should ever use an omni light if you're rendering with mental ray.  If you forgot where it is, you'll have to switch from Photometric back to Standard.








The main catch to making this work is that the omni light must be placed at 0,0,0.  If the light is anywhere else in the scene, the occlusion won't line up with the geometry in the scene, and you'll get really psychedelic results!



These are the settings for the omni light. Under Advanced Effects be sure to check Ambient Only.  This will disable the shadow options.  Also check Projector Map, and insert an Ambient/Reflective Occlusion map here (it's found under Maps->mental ray).  To access its settings you can click and drag an instance of the map into a material editor slot.

I usually leave most of the settings at default.  But I almost always increase the Max distance to something like 4' all the way to sometimes 10'.

To see the results of this in your renderings be sure to turn off any exposure control settings.  You can also turn off any Indirect Illumination in the render settings.

That's it!  What I really like about this setup, especially for complex animations, is that there is no light calculating process, and the renders from frame to frame are very stable and consistent.  The soft shadow effect (ao) also adds virtually no extra render time to your finished rendering.

If you have a tight production turnaround, and are concerned about the lighting in a scene not being designed yet, this is a great solution.




Two more renderings with this technique:


3 comments:

  1. That's very good method. It's a technique that you can reproduce in other software. Thanks for sharing.

    I saw this technique some years ago explained by Master Zap. http://mentalraytips.blogspot.com.es/2008/11/joy-of-little-ambience.html

    Something similar explains the Pixar Lighting TD Jeremy Vickery with his DVD http://www.thegnomonworkshop.com/store/product/981/Efficient-Cinematic-Lighting

    I've tried to do this technique with my cartoon shaolin also.
    https://vimeo.com/22657704

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  2. That's interesting. I like the idea. I took a 3d animation course and my teacher showed us another way to do this but it involves more omni lights so I don't expect it to compare. :D

    Other than that, I think this is a pretty useful tip. Thanks. I just started following your blog because it's interesting and I find that whenever I need help with some mental ray work google leads me here...

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  3. Yeah its a great technique, i use it all the time. I expanded a little bit about it here. http://jamiesjewels.typepad.com/jamies_jewels/2012/05/the-making-of-britney-spears-big-fat-bass-backdrop.html

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