Linear colour space

[tonytrout]

A good model can just as easily be destroyed by a poor render as a poor one made to look a million dollars with excellent lighting texturing and shading. All my MR renders seem to come out dark and dirty, just had Maya for a few months, so i end up pushing the light intensites and photons all over the place. I have bought some Dt and gnomon DVDs and got myself tied in knots with GI and FG and HDRI and blah blah blah....

How important is working in a linear colour space workflow or can I safely ignore it :) until I have a bit more experience?

[Porkpie Samurai]

If your new to lighting you might want to just try concentrate on getting good results without final gather/gi or ever linear workflow. Try just setting up a decent 3 point light setup with some nice raytracing and work on getting your shaders looking good with the lightsetup.

[El Burritoh]

I think one of the reasons Linear workflow is so poorly understood in many segments of the industry (LOTS of folks don't understand it) is that ... in all honesty ... people "have done without it" for a while now, and still get perfectly acceptable results using a non-linear workflow. So there's not as mad a rush to learn it. Don't get me wrong, I'm all for implementing linear gamma workflows in our studio. But it just hasn't reached the point of being an absolute necessity in many studios' workflows.

I mostly understand the process, but I wouldn't mind a good discussion and explanation of it by people who know it in and out. I know most of us here are modelers, not rendering gurus, but if anyone has insight on this, it would be a great topic! In addition to modeling, I spend at least half my time lighting, setting up passes, and rendering. So any info about this would be useful

[tonytrout]

If your new to lighting you might want to just try concentrate on getting good results without final gather/gi or ever linear workflow. Try just setting up a decent 3 point light setup with some nice raytracing and work on getting your shaders looking good with the lightsetup.

Thanks porkpie

Edit

El_Burritoh. Found this link which explains in quite well, theres some other links in there also which are usefull

http://www.djx.com.au/blog/2008/09/13/linear-workflow-and-gamma/

[gal]

the whole issue with linear workflow is your pipeline.
if you use the standard tools out there, max,maya,mr it depends on your rendering engine. vray (even final render) are easy to convert to linear workflow by a click of a button. mental ray however is a whole different case though in max it's less of an issue. in maya however it's a nightmare workflow with mental ray. no one even knows what the correct workflow is. it's unknown what color swatches you have to gamma correct (specifically the mia, sss shaders) it's all an estimation based on what is logical. however maya is buggy and the implements can, and often are, buggy or not fully working. for example the mia shader ISNT physically accruate it balances values incorrectly sometimes.

when we use mr/maya here we do not go with linear workflow unless it's an interior shot or something that requires heavy indirect illumination bounce then the benefit of linear workflow really stands out over the mess you may have to go through by setting it and converting your textures/shaders as you go along.

there is a huuuuuge thread on cgtalk in the maya rendering forum about mr/vray like rendering 250pages long. they explain gamma or atleast try to explain it and find the best solution. good read.

my suggestion dont try to implement it until maya and the mr translator have it on a click of a button working correctly(2011 doesnt have it working right by the way) unless it's some architectural/enclosed env shot..for those i would use it.

[tonytrout]

Thanks for advice gal :beerchug:, yes Im rendering Maya/MR. Thats a long thread at CG talk, I have read a fair bit of it and one of the reasons I started this thread :) So far as I understand it, I de-gamma textures into Maya unless they are 32 bit EXRs, and adjust the rendering while camera is up-gammaed with a gamma correction, that way I see what I want to see, while MR is working in linear space. Sounds simple but Ill just bang away without it at the moment as advised.

Cheers:thumbsup:

[Infinite]

It would be great to hear about other peoples workflows here with LWF. I know Mike Nash and Luc Begin have mastered it in Max with Mental Ray. I have found it hard to use with MR, VRay it's dead easy to setup.

It has taken me a long time to figure out the process I still havent got it setup correctly in Lightwave and allot of this is due mainly to allot of poor information, incorrect discussions, blogs, posts and tutorials that some people have made. I swear allot of people still don't get it and filter out really bad information, which is damaging for newbies like myself who are still trying to get to grips with it.

There are a few gems out there, I will see if I can dig out the links.

[ZippZopp]

i only have experience with mental ray for maya which is quite convoluted unfortunately and i still don't think i've fully grasped it. I haven't really gotten into maya 2011 which is said to have some fixes for helping with linear workflow.

here's my understanding...

i set first set my framebuffer in mental ray to .454 so it will de-gamma my textures for me when i pull them in. i could leave it at 1, but then i'd have to gamma correct each incoming texture. color swatches have to be done with a gamma correction node in order to be correct, which is a royal pain.

i attach a mia_exposure_Simple to my render camera with gamma set to 2.2.

currently, this is my only real understanding of it and am not sure if i'm done everything correctly or not. I'd love to hear from others. and if anyone has tried out 2011, is it working properly now with color swatches?

[tonytrout]

i set first set my framebuffer in mental ray to .454 so it will de-gamma my textures for me when i pull them in. i could leave it at 1, but then i'd have to gamma correct each incoming texture.

Thanks for this tip Peter, saves me gamma correcting every texture :thumbsup:

[ZippZopp]

no prob, i think this is fixed in 2011 so you don't have to set the framebuffer value, but i'm not totally sure, i haven't used it yet. can anyone confirm this with 2011?

[collings]

i can't confirm for maya 2011 but i'm using the same setup as you Peter.

[BrettSinclair]

I've done similar too zipp zopp. I'm testing 2011. It seems all over the place because they've now added a colour space feature in the render globals and the render viewport. Which don't seem too work hand in hand.

Ie if you adjust colourspace etc in your renderview it doesn't show up in a batch render but if you have adjusted the colour space in the render globals it effects the renderview :banghead:.

I decided too stick with the mia photographic attachment too my cam and degamma the textures individually. I leave the framebuffer alone as that seemed too cause wierdness. Heres a blog I recently ran into where he even confessed too leaking bad info :). But tries too make up for it.

http://www.djx.com.au/blog/2010/03/07/maya-linear-workflow-in-two-steps/

[ZippZopp]

thanks for that link brett. it was my understanding that you could either set framebuffer to .455 so you wouldn't have to run the texture through a gamma correct. i guess i'll leave it at 1 now and run my texture through a gamma correct. however, now with 2011, can you scrap the gamma correct node all together and just use the drop down in the texture node to set your color space?

[BrettSinclair]

No problem Peter. Yea it has a colour space option in each texture node or you could use the render global colour space too set a scene colour space instead. Its a bit confusing at 1st cause they've thrown in more options now. I'm actually not even sure if your supposed too use a lens shader or not :confused:.

If anyone figures this all out please share:p

[collings]

here is a video that i found some time ago on the Newtek discussion forum it was posted by username "Matt" .

Video Tutorial: The Beginners Explanation of Gamma Correction & Linear Workflow (http://www.pixsim.co.uk/video_tutorials/The_Beginners_Explanation_of_Gamma_Correction_and_ Linear_Workflow.zip)
Quicktime H.264 15.4MB Zipped

http://www.pixsim.co.uk/gfx/Explaining_Gamma_Title.png

[ashaiad]

Maya 2011 has a slight shift in the color values (if you use the automated linear workflow )
The interesting part is , the values are correct if you to use a solid color, however with a file texture there is a slight shift as I mentioned above

[MikeANash]

Just been learning how to properly use LWF for V-Ray, I found some helpful tuts on how to correctly use it in V-Ray :)

http://www.youtube.com/watch?v=DUhH1O29SG0

http://renderstuff.com/free-3d-tutorial-using-gamma-2.2.php

[Kel Solaar]

If your new to lighting you might want to just try concentrate on getting good results without final gather/gi or ever linear workflow. Try just setting up a decent 3 point light setup with some nice raytracing and work on getting your shaders looking good with the lightsetup.

Actually, those are 2 different things, working without gi / fg but only pointlights or spots doesn't prevent of working in the correct color space / and or compensate for a poor image viewer ( like Maya render view ). One SHOULD ALWAYS work in linear color space, or at least have the feedback of its image in linear color space. Quadratic fallof is meant to work in this color space, lambert is meant to work in this color space. You will even find it's easier to do old school 3 point light setup in linear color space because the lights react properly

KS

[Mrguy]

Just thought I'd weigh in..

It's taken me quite a while to fully understand LWF. I'm a Maya/MR user and have just now fully wrapped my head around it. I really love using it and use it for the majority of my projects. Some things that it fixes in Maya are the "quadratic" falloff for lights. instead of putting in 200-300 intensity just to see light, intensity gets brought back to a working state and you only have to adjust it from 1-2. I also just recently figured out how to correctly use the preview function within the exposure photographic node, so getting the correct gamma has never been easier.

DJX is extremely helpful and has helped me quite a few times, I probobly wouldn't be at the state I'm in without his blog, but don't think that his way is the end all right way. Take what he's saying and just try to expand on it.

I agree with with the majority of people in saying that although I've gotten nice images without LWF, but now I just have more control over my render using a Linear Workflow, which feels like a breath of fresh air.

[mocaw]

I just stick to linear in SI because it makes life so much easier. Granted, you have to be sure you're sources match etc, but over all it just takes some of the guess work out anyway, esp. if you're used to tweaking things a lot outside of the 3D app in PS, or XYZ compositor in passes.

I still do work for that dinosaur known as print, and for that I just simply don't trust my eyes too much- it's all eye dropper matching etc. up to a certain point since numbers don't seem to lie as much. Luckily those projects don't have a lot of dramatic and dynamic lighting! In the end, if you can, it always seems best to view it on the intended source, and if they are more than one, adjust from there. Often it's also good if you can compare between several of the "same" source IE- two of the same monitors calibrated the same way- just to be sure- if you have that luxury.

Thanks to everyone for posting those videos BTW. Never hurts to review those subjects often spoken of and not well understood (like how to comp AO "correctly"). I'm sure to find my understanding is currently lacking.

[SorinLupu]

Hi guys,

Some time ago I watched those videos about linear workflow ... was the best explanation found "for artists". :)

Maya/Mental Ray: Linear Workflow