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 Post subject: Maya rendering problem
Unread postPosted: Tue Feb 09, 2010 1:24 am 
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Hi I'v noticed this problem before some time - maybe 3 months. When I have reflective surfrace witch is behind transparent surfrace - Maya (5.0) don't calculate reflections on it...

On the first image (opened doors) glass have 1.52 refraction index, refraction limit is set to 6 (default) and reflection limit is 1 (default).
Drum have 0.95 reflectivity and no refractions, red ball have reflectivity set to 0.85 and also no refractions. All materials are phong.

Second image have same material/ rendering parameters but doors are closed. Visual deformations of space behind glass are fine, but no reflections at all. Also render times are not adequate 0:18:15 vs 0:03:56.

This is only small object witch will not have impact on whole scene, but I want use glass doors and then effect is huge.

Any hints please?


Attachments:
File comment: No reflections at all :(
bubon2.jpg
bubon2.jpg [ 16.38 KiB | Viewed 738 times ]
File comment: Reflections are nicely visible
bubon1.jpg
bubon1.jpg [ 40.79 KiB | Viewed 738 times ]

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Unread postPosted: Tue Feb 09, 2010 4:11 am 
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Usually 3D software has some sort of "ray recursion limit" that sets the maximum number of bounces/refractions for any single ray. This is to prevent rays from bouncing back and forth many times, which would slow down rendering. If that limit were set too low, it might explain why you're not seeing reflections in the sphere through the glass. Have you tried changing the Reflection Limit to 2 or 3?


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Unread postPosted: Tue Feb 09, 2010 4:28 am 
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My guess is also the reflection limit. Try something higher like 10-12 to rule that out.


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Unread postPosted: Tue Feb 09, 2010 10:57 am 
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yes, and keep in mind that that limit will also affect render times

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Unread postPosted: Tue Feb 09, 2010 12:37 pm 
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Tradaaa :)

My fault - I'v set reflection limit in material editor for drum (chrome) to 4 but I'v not changed it for doors (glass) so it was still 1.
I think that that limit is reached when ray "hits" front of glass doors, so none reflections inside :(
But after tweaking it looks mutch better - this render have reflection limit set for all three reflective materials to 8 - it is bit bright but tweaking is now no problem.
Speed impact is not so tragic. This render tooks 0:41:43 while normal use of O2. If maya have all power of my system it can easily goes down under 0:30:00. Also I'm not planning to look inside "wash machine" (I can't remember right word).

Thanks guys many times


Attachments:
File comment: Reflections are visible behind glass
bubon3.jpg
bubon3.jpg [ 19.75 KiB | Viewed 695 times ]

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Unread postPosted: Tue Feb 09, 2010 1:36 pm 
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Although longer paths will gather more radiance, the excessive brightness look non-physical. Does the metallic reflector have a reflective coefficient below 1 (it should) or is there a light source in there?


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Unread postPosted: Wed Feb 10, 2010 5:19 am 
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Yes reflective coeficient is below 1 - but maya also have "light absorbance" in raytrace/refractive settings witch is default set to 0. I'll try some renders with different parameters to see how it changes.

And no, I don't have light source inside - light is only one default render light from maya (I think it's directional light with no dropoff).

Solution was quite simple - addiding light to scene. I'v addedet directional light with bitmap shadows and vuala: magic is done!

Rendering of this image take - 17 mins when O2 was only rendering and 37 mins when playing music and browsing web (also resolution of shadow map was increased from 1024 na 2048)


Attachments:
File comment: Now, everything looks right - problem solved
bubon6.jpg
bubon6.jpg [ 15.55 KiB | Viewed 652 times ]

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Unread postPosted: Wed Feb 10, 2010 8:27 pm 
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tomo wrote:
17 mins when O2 was only rendering and 37 mins when playing music and browsing web


hehe, never saw that kind of bench :D

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Unread postPosted: Thu Feb 11, 2010 8:46 am 
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Very nice. Looks good.


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Unread postPosted: Thu Feb 11, 2010 9:51 am 
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Wow that's bee-yoo-tee-ful! :shock:

Did you use Maya's built in renderer, Mental Ray, or something else?

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Unread postPosted: Thu Feb 11, 2010 10:33 am 
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vishnu wrote:
Wow that's bee-yoo-tee-ful! :shock:

Did you use Maya's built in renderer, Mental Ray, or something else?

I hope it is not a irony. I'v user maya build in render - becouse mental ray take me long to setup - lights, bit another using of materials and not even talking about rendering times :(

Object (all scene) is *very* simple, so only thing witch can do it nicer/ original was that drum. For better underestand of material setting look in maya how it is made - only one disadvantage for anybody curious will be Slovak language used when naming. I recomend using "select objects with material" from material editor to get imagination...


Attachments:
File comment: Scene with similiar lightning and materials. Notice that the red ball contains 30% of all polygons ;)
pracka.tar.bz2 [77.87 KiB]
Downloaded 25 times

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Unread postPosted: Tue Feb 23, 2010 11:53 pm 
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Personally I think Mentalray will yield far superior results than software, however
memory/system resource management is crucial in order to prevent Maya from crashing on you.



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Unread postPosted: Wed Feb 24, 2010 7:27 am 
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I hate to say it but the rendering looks exactly like Bobo dropped her ball into the washing machine ;)


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