Crazy Homeless Guy Posted October 10, 2009 Share Posted October 10, 2009 Anyone have good tips or a tutorial for atmospheric "God Rays" casting into interior spaces? Yes, I could paint it in Photoshop, but I am more interested in rendering out a separate pass in MR and compositing that in Photoshop. Then I would use that pass to paint them to the look I want. I have briefly messed with the "Beam (Lume)" shader, and the "Parti Volume (Physics)" shader with little to no luck. I am not sure if that is the direction to keep working with, or if I should look elsewhere. Below is a link to an extreme example of what I am trying to create. http://upload.wikimedia.org/wikipedia/en/7/7c/Crepescular_rays_in_saint_peters_basilica.JPG Link to comment Share on other sites More sharing options...
rmccoy Posted October 10, 2009 Share Posted October 10, 2009 Can you use a volumetric fog? not sure how it's done in mental ray. I remember reading a tutorial about achieving that effect Link to comment Share on other sites More sharing options...
rmccoy Posted October 10, 2009 Share Posted October 10, 2009 try this tutorial http://3dsmaxrendering.blogspot.com/2009/03/parti-volume-shader.html Link to comment Share on other sites More sharing options...
Crazy Homeless Guy Posted October 10, 2009 Author Share Posted October 10, 2009 Nice find. I will run through it shortly. Link to comment Share on other sites More sharing options...
TheAllusionisst Posted October 10, 2009 Share Posted October 10, 2009 One of Jeff Patton's tutorials on the parti shader" http://www.mrmaterials.com/jeffs-blog/78-partiwoohooo.html Link to comment Share on other sites More sharing options...
Crazy Homeless Guy Posted October 10, 2009 Author Share Posted October 10, 2009 (edited) Thanks for the additional link. Here are my initial results with more or less the default settings for ray dispersion. Trust me when I say my render times are not winning any speed awards. Currently my render times are increasing by 4 when I apply this. Granted, I just dialed in settings that I knew would give me good results based on the tutorials posted. I need to go back and tweak the settings for quality vs speed. I did manage to assign this shader as a render element, and apply it in post. See the second image below. However, this only saved 10 seconds in the render time. Minimal, but does give me the control I will be looking for when I go to use this in production. I did loose some of the atmosphere around the Parti Volume rays that were created when they were rendered separate from the beauty pass, but as you can see when comparing the first image and fourth image. The atmosphere can be painted in post with a screen transfer layer fairly easily, as shown in the fourth image. EDIT: Replace my use of the term glare in the composited images with volume rays. I did have glare enabled when rendering these, but there impact on the overall image was minimal. I think. Though I had it disabled when rendering the background plate for composite, so the glare may have actually contributed to the lost atmosphere that had to be painted in later. Edited October 11, 2009 by Crazy Homeless Guy Link to comment Share on other sites More sharing options...
SandmanNinja Posted October 10, 2009 Share Posted October 10, 2009 I think it looks great, Travis. I've been wanting to do an Ancient Temple with God Rays bursting through the holes in the roof - think I've found the way to do it now. Good job. Link to comment Share on other sites More sharing options...
Macer Posted October 11, 2009 Share Posted October 11, 2009 Thanks for the info. I've been meaning to come up with a good solution to achieve this effect in my own workflow for ages, but just never got around to it! Link to comment Share on other sites More sharing options...
pixelperfectg Posted October 11, 2009 Share Posted October 11, 2009 You can also use the default volume effects with mental ray. See #18 in my FAQ: http://forums.cgsociety.org/showpost.php?p=2921693&postcount=2 Generally speaking the parti-volume will be more accurate while the default volume effects will be a bit faster to render. Also FWIW I have a video on the topic here: http://www.thegnomonworkshop.com/includes/bundles/jpa_bundle.php#fragment-3 Link to comment Share on other sites More sharing options...
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