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#1
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I can count to potato!
Join Date: Aug 2004
Location: SC, USA
Posts: 2,733
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Hot topic - Linear workflow in 3dsmax (Mental Ray & V-Ray)
I know some of you (especially the Vray folks), are familiar with the "new" linear workflow tweaks. Last night I spent some time reading these concepts and I must say that I think I'll start implementing some of the ideas.
Here's the original information on linear workflow:
http://throb.net/site_main/LinearWorkflow.html
Then this information also helps to clarify the process:
http://www.gijsdezwart.nl/tutorials.php
IMHO, it's basically like adding linear exposure control to Mental Ray (or any renderer I suppose)...but since MR only works with logarithmic exposure control...it's great to have another option.
I'm attaching a test that shows the difference. In the adjusted gamma render, I get a nice even light distribution on the interior & exterior. Of course the exterior has some over bright areas..but this was just a test (no real tweaking on the light levels, materials, etc).
So, set aside a little time to review the links above and see if this is something that helps to improve your workflow. |
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December 7th,2005, 10:04 PM
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#2
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Administrator
Join Date: Nov 2003
Location: Jacksonville, FL
Posts: 4,974
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Damn man this is impressive information...mucho brownie points
__________________
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steven d. papke
vizdepot.com, owner
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Awesomeness
When I get sad, I stop being sad and be awesome again....true story.
Barney Stinson
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December 8th,2005, 03:52 AM
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#3
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the nice moderator..
Join Date: Jul 2004
Location: UK, Manchester
Posts: 2,389
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Jeff, that's good info - I've adjusted gamma setting in the Preference Settings before - never tried it with MR.
How did you get that nice green tint glass at the back? - I would expect it to be black - because your environment is black...
jana
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December 8th,2005, 10:07 AM
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#4
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I can count to potato!
Join Date: Aug 2004
Location: SC, USA
Posts: 2,733
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That green color is just the refraction of the HDRI environment. I forgot to use a special shader to eliminate that. For me, it's an unwanted artifact because I only want the glass to reflect the environment, and not show up in the refraction.
In the MR shader thread at CGtalk, A fellow by the name of Stephen Gustafson (aka -Vormav-) has supplied several shaders that he's written for MR. One of them prevents this refraction...and allows glass to only show the reflection. It's a very handy shader.
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December 8th,2005, 10:57 AM
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#5
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Used Register
Join Date: Dec 2003
Location: Tampa
Posts: 1,978
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Would you still change gamma form the default 1.0 on the render save, if it was corrected in the preferences already?
__________________
John 8:12: "Then spake Jesus again unto them, saying, 'I am the light of the world: he that followeth me shall not walk in darkness, but shall have the light of life,"
Cesar Lopez
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December 8th,2005, 11:05 AM
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#6
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I can count to potato!
Join Date: Aug 2004
Location: SC, USA
Posts: 2,733
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Yes. When you save an image, if you leave it at "use system default" it will be saved with gamma 1.0. Even if you have changed the gamma in the preferences. At least that's how it worked here. I couldn't figure out why my saved images didn't match the actual frame buffer render...it was that darn gamma setting when I'd save the image. I'd never even noticed that setting being there! lol.
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December 8th,2005, 11:25 AM
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#7
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Used Register
Join Date: Dec 2003
Location: Tampa
Posts: 1,978
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Good to know, thanks.
__________________
John 8:12: "Then spake Jesus again unto them, saying, 'I am the light of the world: he that followeth me shall not walk in darkness, but shall have the light of life,"
Cesar Lopez
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December 27th,2005, 03:02 PM
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#8
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Registered User
Join Date: Dec 2005
Location: Seattle, WA
Posts: 29
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I gave this a shot in a scene I've been working on, adjusting the gamma in the preferences and the bitmap input gamma both to 2.2 as the article suggested and it did lighting up the darker areas of the scene but I noticed it also washed out a lot of my color.
Any suggestions as to something I could do differently to keep my colors vibrant? Or perhaps I didn't read carefully enough and missed something. I'll take another go at it after work and perhaps post my results.
-Mad.
**Edit**
It may just be the types of lights I'm using and their intensity that's blowing the color out of my renders.
I did a test render using a cornell box with the correct gamma and this is what I came up with:
Last edited by gone.mad : December 27th,2005 at 09:17 PM.
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December 28th,2005, 09:39 PM
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#9
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Registered User
Join Date: Jun 2004
Location: Charlotte N.C.
Posts: 561
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Jeff, i have been using Gamma correction since viewing chris DVD Interiors. I also notice even with gamma correction, my labtop displays the image differently from the desktop. dont know for flat screens. For more information on linear work flow check out the chaos forum
Cecil
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December 29th,2005, 01:55 PM
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#10
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I can count to potato!
Join Date: Aug 2004
Location: SC, USA
Posts: 2,733
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Yup, you lose a good bit of the contrast when using the 2.2 gamma correction. However you also lose a lot of the nasty color bleed issues. Some quick contrast adjusting in Photoshop will help darken the shadows.
I'm attaching some cornell tests of mine. These are also using a photometric area light with raytrace shadows & GI only (no FG).
DGS materials with no reflectance.
Red wall = R:0.5, G:0.01, B:0.01
Green wall = R:0.01, G:0.5, B:0.01
White walls = R,G,B all set at 0.9
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January 18th,2006, 12:13 AM
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#11
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Twilight Render Addict
Join Date: Sep 2005
Location: Milwaukee, WI, & Rovinj, Croatia
Posts: 396
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gone.mad, and/or j.p.,
Could you please post your Cornell box in a format Viz4 can open? I would really like to practice with it. Thanks.
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January 18th,2006, 06:06 AM
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#12
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designer
Join Date: Jun 2004
Location: south africa Gauteng
Posts: 1,669
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well, im working on-gamma 1.8.................3ds max actually states that it should be 1.75-gamma
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Nothing in life is HARD to do, it only takes TIME-MARIUS ERASMUS
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January 18th,2006, 09:49 AM
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#13
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Used Register
Join Date: Dec 2003
Location: Tampa
Posts: 1,978
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I prefer 1.5, I find higher gets washed out.
__________________
John 8:12: "Then spake Jesus again unto them, saying, 'I am the light of the world: he that followeth me shall not walk in darkness, but shall have the light of life,"
Cesar Lopez
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January 18th,2006, 09:58 AM
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#14
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It never hurts to help!
Join Date: Oct 2004
Location: Netherlands
Posts: 2,131
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Ins't it the same effect as increasing your ambient?
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Laurens van Harten
Home: AMD 64 X2 3800+, 2Gb DDR, GeForce 7600GT 256Mb.
3dsMAX 2009, ADT 2009, Photoshop CS3
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January 18th,2006, 10:14 AM
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#15
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Moderator In Training
Join Date: Feb 2004
Location: Traverse City, MI USA
Posts: 1,363
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You guys need to read this page: http://www.gijsdezwart.nl/tutorials.php
as well as the 3 links at the bottom of that page.
For starters, make sure your monitor is calibrated correctly. To calibrate, you need to set your whitepoint, then your blackpoint, then adjust the driver so that your monitor displays a gamma of 2.2. Then, using the linear workflow as described will work.
If you don't do this, then everything you do on your system (MAX gamma, PS adjustments, etc.) is a bandaid, and everything that you send out will be non-standard. |
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