Volumetric Lighting on Maya/Mental Ray 2008

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Nemesis_41

Nemesis_41

Snore PHD
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Since i have to do the lighting in my project.. i decided to go with volumetric lights to get the so called "God Rays" :P.

The problem is that i cant post my scene here as its a copy right issue and we aren't supposed to release it to the public..lol

Now my major issue is getting the parti_vol shader attached to my cam to work right. I've been trying this for a while but i'm just not able to get good results..lol

Kippu helped me out by sending me a few links.. but my output isn't working.. maybe im missing something?

Workflow: HD720 Cam> mental ray options > vol.shader > parti_vol shader > light linked to 3 spot lights in mode 0(parti_vol mode)

This setup seems to work better with a directional light but i'm not able to control the r,g1,g2 options too well.

R = favoring between g1 and g2 settings

g1 and g2 = distance of scattering between each other.

Help!

Examples :

bigstockphoto_Rays_Of_The_Sun_73840.jpg


foggy_forest_1680x1050.jpg
 
I dunno so advanced stuff but I did learn in Digital Tutors ka tutorial you can use fog and it has the same result :D ....
 
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^ not really.. volumetric lighting is difficult yes but i doubt the result is as accurate with fog. thanks anyways :)
 
Erm yea you would have to do the tweaking ... I did it for a lame pen stand with 3 pends in it and the light source was a lamp ... if you want for a forest well I'll have to model a forest first and then try :P
 
Scorpy said:
Erm yea you would have to do the tweaking ... I did it for a lame pen stand with 3 pends in it and the light source was a lamp ... if you want for a forest well I'll have to model a forest first and then try :P
Click to expand...

Already have a modeled forest scene.. i tried faking it.. crap quality.. so i ditched it :bleh:
 
SoMxNemesis said:
Already have a modeled forest scene.. i tried faking it.. crap quality.. so i ditched it :bleh:
Click to expand...

You don't actually need to render the forest, just the lighting which can be composited back into shot. Change the settings so that the forest does not render, but so that the light and shadows still do. ;)
 
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PiXeLpUsHeR said:
You don't actually need to render the forest, just the lighting which can be composited back into shot. Change the settings so that the forest does not render, but so that the light and shadows still do. ;)
Click to expand...

oh yeah.. :! :bangin: ..i never thought of that..lol thanks PP.
 
Ill try to do it with some basic pillars and see if I have any success in getting the final result ..
 
Eh I tried .... but I just couldnt get the god rays ... I used tall cylinders to act as pillars and used spot light ..... then I increased the angle of the spot light considerably and used fog ... rendred with mental ray .... but the god rays just arent coming :/ .... I will have to do more tweaking
 
^^ you should still try and use volumetric lighting as you can add volume on top of having objects to shine through. The tress do not have to look real, just enough to shine light through. :)
 
PiXeLpUsHeR said:
^^ you should still try and use volumetric lighting as you can add volume on top of having objects to shine through. The tress do not have to look real, just enough to shine light through. :)
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btw ... I dunno what volumetric lighting means ... :p .... i just saw god rays hence I tried to help :P ... can you explain what it means :D ? and I didnt understand what you were trying to say .... objects to shine through O.o ... damn I need to stop those modelling tuts and go to rendering :/
 
Another idea - try using a gobo (projector alpha map or so) for the light, it should work very well with a volumetric light.
 
Scorpy said:
btw ... I dunno what volumetric lighting means ... :p .... i just saw god rays hence I tried to help :P ... can you explain what it means :D ? and I didnt understand what you were trying to say .... objects to shine through O.o ... damn I need to stop those modelling tuts and go to rendering :/
Click to expand...

The wikpedia explanation posted by floccy explains it well. If you use objects (like trees) to shine the light through (to make God rays and shadows) and also volumetric lighting with a good shadow map, you should be able to tweak some nice lighting. I was suggesting to SoMxNemesis that instead of rendering the tree's, he may get better results just rendering the light as a separate layer by making the tree's invisible to the rendering engine (or camera render view) and then compositing them into the footage after... with maya or a video compositer like after effects or shake or nuke or something similar.
 
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