I Hate Mr Area Light ...

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  12 December 2006
I Hate Mr Area Light ...

Right, I dont want to raise any quarrel about vray and MR, or any offense, but this is the fact I encouter everyday, and I must say: I hate MR area light.
I know when I say that, many will say: NO, it s great, it could give soft shadow,fast setup with physical light, It could emit photon, it.... etc... Right, I know it s useful, but I still hate it.
I will go straight to the mater
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First, you could view this pic of slipknot66 vbmenu_register("postmenu_1962277", true); . This is great pic of lighting, shading, rendering
http://www.cgnetworks.com/gallerycr..._1091670128.jpg
But, please look at the ceiling near the door, do you see the noise, the strange noise...
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Another look at dagon tutorial
http://www.treddi.com/forum/index.php?showtopic=8436
You may have known it, you could follow this tutorial and tell how could you advoid all the noise at a aceptable time.
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You may say that: No, it s acceptable time. So I will give me simple case, an interior render
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First, I want to give vray and MR the sample condition and render method. I know it seem craz. But the balance method I think is

method of Vray is

Quote:
  • Vray 1.5 core
  • IRR + Lightcache + expotional color mapping.
  • AA is -1,2 adaptive with area filter
  • 1 Vraylight + directional light for sun.
  • Vray grey diffuse only material


And MR is

Quote:
  • MR 3.5 core
  • GI + FG + buffer.api for color mapping
  • AA is -1.2 with box filter
  • 1 MR area light,-physical light- emit photon + directional light for sun
  • ctrl_shading grey diffuse only with mib_photon_basic. I think this is fastest shader for diffuse color testing only.

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And now, the only thing left, I try to compare render time and area light noise eliminating
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First, a picture of MR

32 sample in area light for noise reduction :(. Time 2.19 min
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Second, a picture of Vray

12 sample (sub-div) in area light for noise reduction. Time 2.04 min
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I dont want to discuss about math of 2 renderer, but only look at the way each solve with noise
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  • Vray area light distribute noise the overall pic, and sample raise help us eliminate noise
  • MR area light distribute noise the overall pic but noise is more density at the area light edge. That s way we raise sample, the noise at other is out, but the noise at light edge still remain and a very high sample still not kill all of them...
====
It s just my comparision and at this time, I cud not find a way to elimiate the noise with less time. Or maybe my technique is too bad to use MR :(.
But the fact area light noise distribute and how to reduce them in MR is terrible
================
PS: This may be a long thread, hope anyone cud read throgh and help me find a way to get off this stuk :(. A method such as reduce contrast threshold and raise light sample is okie, but I dont want to trade so many render time like that :(

Last edited by ghostlake114 : 12 December 2006 at 01:40 PM.
 
  12 December 2006
ghost, your comparison is a little bit strange on my eyes:

-if you want to compare mr_arealight with vr_arealight why you introduce so much factors?
a better approach could be to disable the Global Illumination and tonemap, and compare the difference in a simple raytracing render
another approach could be to use just the Irradiance Cache (IRM-vray, FG-mray), with similar settings (the FG in mray3.5 is very similar to the vray IRM) and compare the difference in a quasi-gi mode
i made this kind of tests many times, i could say, the new mray area lights can be faster in some scenes and slower in others.. rendertimes aren't so different compared to the vraylights

-you may use an harder scene to test, or an higher resolution, because 10/15/20 seconds on a 2minutes rendering scenes aren't really important (could be a matter of faster/slower exporter etc), try at least a 15/20 minutes test
 
  12 December 2006
Please, can you post your MR Area Light (Hi - Limit - Low) Samples? You'll probably find the solution there...With a 25 -2 -5 setting I usually get good results in not much more rendertime.

Quote [dagon]: -you may use an harder scene to test, or an higher resolution, because 10/15/20 seconds on a 2minutes rendering scenes aren't really important (could be a matter of faster/slower exporter etc), try at least a 15/20 minutes test - END Quote.

You're right dagon, but he's probably pointing at the grainy shadows on the ceiling of his test room with MR, compared to the clean soft shadows of the Vray version; ghostlake spent much rendertime to obtain a grainy result with MR. That's the matter I think...
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Last edited by fabergambis : 12 December 2006 at 03:51 PM.
 
  12 December 2006
Originally Posted by fabergambis:
You're right dagon, but he's probably pointing at the grainy shadows on the ceiling of his test room with MR, compared to the clean soft shadows of the Vray version; ghostlake spent much rendertime to obtain a grainy result with MR. That's the matter I think...


i saw, but the adaptivity of the new mr area light (in maya8) works quite well, so, you can increase the samples without a great cost for rendertimes
comparing 2 minutes with (let say) 3 minutes is not a great idea for a good test, especially if you have so many factors in your scene
 
  12 December 2006
@dagon:
I include too many factor for the real comparision in working. GI+FG is the good solution for interior like IRR+Lightcache. The tonemap is only additional for quality purpose.
AA and filter is in the same condition
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With all that thing, the area light in each renderer works so different. The way MR light distribute noise and eliminate them is really problem that I want to show.
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I could say in this case, I even raise high sample of MR area light to 100 and low is 25. The noise still somewhere in the light edge.
------
Ya, light edge noise distribution is so anoying, compare with overall noise distribution of Vray light.
==
 
  12 December 2006
i have a completely different opinion, and i'm quite sure of what i'm talking about
if you include GI in your test you can't control the time contribution due to the area light sampling, especially if you use such a low rendertimes!
low samples at 25 make me think you dont know what you are trying to do, because in a diffuse scene the low sample is not working (is the samples level for reflective/refractive surface, where you see reflective surfaces in your render??)
and the low sample actually increase a lot the FG map calculation

and this is a demonstration that less factors = less mistakes
 
  12 December 2006
Ya, high sample only test (100). But I do not get all what you say. What do you mean with "include GI in your test you can't control the time contribution due to the area light sampling, especially if you use such a low rendertimes". I include GI+FG just want to give a total test in a real work, not an independent test only with Area light.
===
The Vray is for demonstrating only, show how vray deal with light sample in a real work.
 
  12 December 2006
Originally Posted by ghostlake114: I include GI+FG just want to give a total test in a real work, not an independent test only with Area light.

and this is the problem, because if you wanna test how an area light work you have to start with a basic light setup, without GI and without any other factor (like a direct light, for what?)
how do you think the GI+FG setup changes the behaviour of an area light (if you use it correctly!)?
 
  12 December 2006
For this simple scene, I try to keep GI and FG in smooth render without GI artifact. As you could see, the only left is the noise come from area light. I do not think this come out from MR area light. --- SORRY, GI AND FG, not MR area light, MY MISTAKE CUZ THIKING WHEN TYPING
The fact, I also view many interior render (not yours, dagon ), and they share the same problem as slipknot66 in my first post, the weird noise artifact in area light edge :(

Last edited by ghostlake114 : 12 December 2006 at 07:06 PM.
 
  12 December 2006
Originally Posted by ghostlake114: For this simple scene, I try to keep GI and FG in smooth render without GI artifact. As you could see, the only left is the noise come from area light. I do not think this come out from MR area light.
The fact, I also view many interior render (not yours, dagon ), and they share the same problem as slipknot66 in my first post, the weird noise artifact in area light edge :(


yeah, and this is due to the lack of previous mr area lights (points)
the new adaptive system works very good, i can post an example in an heavy scene
 
  12 December 2006
Quote:

yeah, and this is due to the lack of previous mr area lights (points)
the new adaptive system works very good, i can post an example in an heavy scene


===
It seems interesting, adaptive system. Could you be more specified, dagon...
 
  12 December 2006
ok, this is an example of what i'm talking about

Vray 1.5 RC2 for 3d Max
AA:
Adaptive Subdivision -1 2
Mitchell size 4

vraylight

samples 8 (default) 10:44


samples 25 15:48




Mray 3.5 for Maya
AA:
-1 2
Mitchell size 4

physical area light

samples 8-1-1 (default) 3:13


samples 32-1-1 5:56


samples 256-1-1 9:33
 
  12 December 2006
Sorry dagon, so you raise the sample to 256 for noise eliminating
So what do you mean about adaptive system in new MR 3.5 ???
===
By the way, the render time in this case is so cute .
 
  12 December 2006
heya dagon
never used vray but i have a feeling vray somehow uses the indirect ilumination map ( "fg" ) to smooth out the noise in the shadows...?

could you test vray with
> a indirect illl OFF and area shadows ON scene and
> a indirect illl ON and area shadows ON scene
to clear this up?

salut,
calin
 
  12 December 2006
i mean, with the new area light you can increase the samples without high-time costs
this was impossible in the past area light (point), i usually used some kind of tricks (AA/contrast threshold/ect)
the real difference between the mr area light and the vray lights is visible in simple scenes (like your), the mr area light dont like a surface too close to the light (like the windows) the vraylight instead works better (seems like a cutoff to the closest object, if they aren't important)

but if you move you exclude the vertical part of the windows to the shadows and you scale a little bit down your area light the mray render can be much faster
 
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