The Linear Workflow Challenge....!

[landrvr1]

I'm relatively late to the LWF party, and have used it with success on exterior scenes. However, I've really been struggling with those scenes in which their is little or no access to the natural daylighting provided by and HDRI dome and/or VRay sun. I do a lot of office interior work, and the deeper you go into a space the harder it is to get LWF to actually look decent. In fact, LWF for scenes without daylight access seem pretty dreadful in the tests I've done. Lack of constrast, a common complaint, is the biggest problem.

 

What I'm wondering is this...does LWF make sense when you have little or no daylight in the scene? Has anyone gotten it to work? Can anyone get it to work? That's the challenge...

 

While using VRayDirt as an occlusion pass could help, I want to avoid this... Let's keep it as pure as possible. The test images have been unretouched. There's a VRay Sun outdoors, but no HDRI. A standard VRay light has been used in the interior. A VRay camera has been used for all shots, with no changes to exposure in the different tests. All other VRay settings are pretty standard stuff. I'll post them if necessary.

 

 

larger image:

http://www.802studio.com/LWF/LWFtest.jpg

 

 

There's a far greater richness in tone and contrast in the non-LWF example at the above left. Note the subtle yet all important shadow just under the pillow on the bench. None of the other LWF tests even seem to pick this up that well! The shadow under the small laptop stand in front of the bench is also deep and well defined. There's simply an overall loss in contrast with LWF - at least in my examples. Certainly the non-LWF could use some increase in exposure to bring out the whites, but overall it's a much better place to start than the others.

 

I'm perfectly comfortable sticking with nonLWF for interior scenes, but this has really been bothering an associate and I for quite sometime; especially when you look at Alex Roman's Auditorium - which was done in LWF without the benefit of any exterior lighting! He's getting beautiful midtones and great contrast right out of the box - without any ambient occlusion layer or tricks:

 

http://en.9jcg.com/comm_pages/blog_content-art-166.htm

 

Any suggestions or tips would be most helpful.

[Ismael]

http://www.jamesshaw.co.nz/blog/?p=155

 

The lighting in your sample is too even. How are you lighting the space?

[Bruce Hart]

Just a couple of thoughts - I shifted from Mental Ray to Vray a few years ago now, and found a myriad of different workflows on-line. Like you I played around with dropping the secondary GI level down (after reading a tutorial). However this is a bad idea. The problem I really had was many of my materials were too bright - resulting in too much light bouncing and a subsequent lack of contrast. These days I set "White" for example to 220.

 

Personally I use a Gamma of 1.8, to achieve some contrast but of course this is not "correct".

[Francisco Penaloza]

I think there is a missed interpretation of concepts here, check the link that Ismael posted and try to understand the concept not just focus on the workflow.

Using day light or HDRI or IES does not equal LWF.

if everything is setup the right way, your image would look fine, maybe you don't have the right lighting in your scene, or your GI solution is to low.

there is not LWF if you are using Exponential Color mapping, because you are limiting the bright and dark areas with Exponential, that's what it made for, the same thing with reinhard

Now from the artistic point of view, LWF does not equal a good image always, that's why VRay has all the possibilities, because it is up to the artist to use what ever he think will make the image look better.

if you want us to help you with your image, please post your render settings, what are you using as a first and second light bounce, how many samples and so on, for what I see it seams that you have low sample and high interpolation, that's one of the typical setup that looses the detail or AO in the corners, have you tried using enhance detail in your irradiance?

[Nic H]

there are more variables at work than your colour mapping settings

what lights? how many?

what materials? bitmap? rbg colours? how bright?

 

your setting and examples are so out of wack its hard to know where to start. dont fiddle with secondary bounce and leave those dark and bright multiueplers alone for the time being

[Scott Schroeder]

I'm perfectly comfortable sticking with nonLWF for interior scenes, but this has really been bothering an associate and I for quite sometime; especially when you look at Alex Roman's Auditorium - which was done in LWF without the benefit of any exterior lighting! He's getting beautiful midtones and great contrast right out of the box - without any ambient occlusion layer or tricks:

 

Any suggestions or tips would be most helpful.

 

Alex Roman does heavy post work on his renders, which is where a lot of his color and contrast come into play. Quite honestly, the out of Vray render should be a base that you take into post and do all of your final adjustments there. It is much faster to dial in your contrast in post than it is in the render process. Don't think that your fresh from Vray render has to be the image you send to your client. It should be 80-90% there and the rest comes later.

 

 

The most common mistake in LWF is double correcting your gamma, then making wacky settings adjustments to adjust for the first mistake. Are you 100% certain you are not accidentally double correcting your gamma? There really is no need to for some of those multiplier settings that you have, unless you are feeding the image through the gamma process multiple times.

[landrvr1]

Tnx gents for all the comments. It's truly appreciated. I thought I'd do a couple of test shots in which there is an override material of white. I suspect that part of the issue is how the bitmaps/RGB colors are being handled and I want to eliminate that from the equation for now.

 

In both examples:

There's a single VRay light (mesh) rectangle that follows the interior plan.

White is RGB @ 220.

VRayCam was used in both, but f-number was raised in the LWF example to compensate for the stronger light spread.

 

The settings jpg below is for the LWF version..

I'm doing a linear color mapping here...no fidgeting this time, lol.

 

While I certainly realize there's usually an enormous amount of post work that's done to bring out the contrast and mids, I've seen raw examples out of VRay with linear in which the contrast is much better than what I'm achieving - in spaces with no bright light source such as what you'd get with a sun in a HDRI dome. In fact, Alex Roman's auditorium is a great example of this:

 

http://en.9jcg.com/comm_pages/blog_content-art-166.htm

 

Look at that raw render example and note that tiny but fantastic shadow at the first seat closest to the camera -Right between the folded up seat and the back. There's a beautiful, VERY distinct shadow happening there.

[Francisco Penaloza]

Since you are using Alex Roman tutorial as reference, did you noticed that he put a VRay Light in every single light equipment? even in the ceiling lighting instead of using a mesh he placed several lights filling the space. Why this? well because this way you'll get the same effect that it may happens in real light, some areas will be very lit others no, you'll get contrast, color variance, that's what make a image more pleasant, if you lit your scene with a giant light, the shadows won't be right, everything will be evenly lit, it will look just the way you are showing.

Take your ceiling plan (CAD) and see where the architect places the light equipment, and place the lights there, if you get very dark areas, then start to putting filling lights, but start flowing the architect plans.

Also your interpolation on IRR is to high IMO, again check Roman's settings, do not just copy them but analyze and try to understand the relation between samples and interpolation that's the key for details in shadows.

Also when you save your image if you save a JPG you need to save it with gamma 2.2 if you save it as float 16b or 32b you need to save it a gamma 1.0

From your image your LWF is doing exactly what it supposed to do.

[Scott Schroeder]

Your washed out image is pointing to double correction of gamma as one of your problems.

 

You might want to consider using "don't affect colors" if you are using your current gamma settings.

[landrvr1]

@Francisco, yes I noticed that about Alex's setup. I've tried that approach as well in a couple of different ways:

 

Used accurate IES data for those light fixtures and placed them according to the reflected ceiling plan. No real change.

 

I've also done a series of smaller VRay plane lights scattered throughout the space - approximating the placement based on the actual fixtures - and that also offered no real change.

 

I agree with your assessment that LWF is doing exactly what it's supposed to do...!

[landrvr1]

Your washed out image is pointing to double correction of gamma as one of your problems.

 

You might want to consider using "don't affect colors" if you are using your current gamma settings.

 

 

Hmm, not following the 'double correction of gamma' comment. ? When unchecking don't affect colors it certainly gives me an overall darker image with more contrast; which can be altered in post...

[Francisco Penaloza]

Hmm, not following the 'double correction of gamma' comment. ? When un checking don't affect colors it certainly gives me an overall darker image with more contrast; which can be altered in post...

 

Yes and not, when you check don't affect colors what it does is VRay uses your gamma corrections (Set up to 2.2) to calculate GI but it does not burn this in your image so you can keep working in a linear environment in post production, that's why the image look dark, Gamma 1.0

When you un check that option, VRay is burning this corrected gamma 2.2 in to your image.

that's why VRay buffer has the option SRGB that you need to use if you are turning on this option.

Again with the best intention I strongly recommend you to read the manual of VRay, or online help from 3dspot.com and understand the bases of LWF, I can see that you are confused with what you know now. if the Linear workflow is set it up right, and lighting is ok your image should work fine, no dark image, no washed out renders.

I can tell you to setup Max to 2.2 gamma, leave output to 1.0, setup VRay to gamma 2.2 use linear color mapping, and check do not affect colors and also use SRGB button in VRay buffer, but if you not understand the "way", then when you have lighting problems like now, you'll have too many variables that you won't know where to start, and again having a giant self illuminated polygon in your ceiling wont give you the lighting that you are trying to archive, believe me.

[Francisco Penaloza]

as a side note I know excellent Viz Artist that do not use LWF at all and still they produce great images, if you think your method works better for you, for all means go with it. if you can produce quality work nobody will question your workflow. I am just giving my opinion because you mentioned that LWF does not work, just to be clear, I think is a problem or process and application, not a problem of concept.

[Bruce Hart]

As mentioned by Fancisco - what is the status of your SRGB button in these renders? Or are you using the Max Frame buffer?

[landrvr1]

Again with the best intention I strongly recommend you to read the manual of VRay, or online help from 3dspot.com and understand the bases of LWF, I can see that you are confused with what you know now. if the Linear workflow is set it up right, and lighting is ok your image should work fine, no dark image, no washed out renders.

I can tell you to setup Max to 2.2 gamma, leave output to 1.0, setup VRay to gamma 2.2 use linear color mapping, and check do not affect colors and also use SRGB button in VRay buffer, but if you not understand the "way", then when you have lighting problems like now, you'll have too many variables that you won't know where to start, and again having a giant self illuminated polygon in your ceiling wont give you the lighting that you are trying to archive, believe me.

 

 

Believe me when I tell you that I've read an ENORMOUS amount of material on LWF. I understand both the concept and what the settings do..sorry if I've led you to believe otherwise. Whether or not the 'Do not affect colors' is checked or unchecked is, I believe, irrelevant to getting better contrast from deep interior scenes with little or no natural lighting - straight out of VRay. Burning the gamma into the image is a technique used by many people, but plenty also leave that for post...

 

aversis talks about this quite a bit:

http://www.aversis.be/tutorials/vray/vray-20-gamma-linear-workflow_03.htm

 

 

The purpose of this thread was, in all honesty, to throw down a challenge: Can anybody actually get fantastic contrast and depth image using LWF with little or no access to daylighting? PRE-POST!

 

There's been a lot of great comments and tips, but so far the challenge still stands! Ronen Bekerman's site is fantastic and I visit often. Yet, not a single 'making of' that uses LWF shows anything but scenes with access to powerful outdoor lighting rigs - where getting amazing shadows and beautiful contrast is...well...easy!

 

I want to see someone create a LWF interior scene with NO access to daylighting, in which the shadows are deep, contrast is rich, and no post work is used.

 

I'm more than willing to share my file if anyone is interested.

[Francisco Penaloza]

post the scene then, I am up to give a try.

[notamondayfan]

LWF does not equal amazing lighting and rendering.

 

Having direction, contrast, and planning how to light the space is the key here. If it were my scene I would either be dragging light from the background to foreground, creating gradients of light from front to back, or I would light from left to right, casting shadows onto the left wall. LWF is about controlling the falloff from light to dark, not about creating interesting lighting.

 

Dean

[landrvr1]

@Dean, I agree completely with what you're saying.

 

 

Let me also add this into the mix: I do quite a few films with office spaces like these; where the camera is moving around all over the space in various shots. Setting up any sort of special lighting rig that would really only work in still shots just isn't practical so the solution has to be a universal one for the entire office space. There's plenty of interesting techniques I could employ with that shot, but the rig would have to be moved for every new camera location and that's just not possible with the deadlines. I'm getting the file ready for upload...

[landrvr1]

Here's a download link to grab the scene. If you get some great results the only thing I ask is that you post your settings and/or offer another download. I'm eager to learn how to do this, and hope this thread will help others as well. Tnx!

 

https://hmi.box.com/s/epjjcdsb124be516ja9d

[beestee]

The purpose of this thread was, in all honesty, to throw down a challenge: Can anybody actually get fantastic contrast and depth image using LWF with little or no access to daylighting? PRE-POST!

 

What is the purpose of dismissing post-processing for a workflow in which it was intended as part of the process?

 

The benefits of LWF all come from lack of contrast in the rendering phase. Better light reach in low-lighting situations, faster light solving by the render engine, and more range of control over the tones and contrast in post.

 

Here is a quick raw render test for no post-pro contrast using LWF:

 

And the wireframe:

 

Here is the image saved out with improper gamma adjustment at export:

 

Here is some minor post-pro levels adjustment:

 

These were all produced with "baked gamma" linear workflow.

Edited July 30, 2013 by beestee

[Scott Schroeder]

Your whole set up is going to fight any sort of contrast by nature of what you are rendering. Open space office/cubical farm plans have extremely even lighting in reality. You won't see much light contrast if you walked into that place when it is built in real life, so don't really expect anything to be eye-popping when you render.

 

I'm sure we've all seen the Gamma 1 vs 2.2 grayscale image.

Where in all of that glorious gray of 2.2 are you going to get contrast? The answer is in bestee's post.

 

What is the purpose of dismissing post-processing for a workflow in which it was intended as part of the process?

 

The benefits of LWF all come from lack of contrast in the rendering phase. Better light reach in low-lighting situations, faster light solving by the render engine, and more range of control over the tones and contrast in post.

 

You are going to spend days trying to get that 10-20% contrast out-of-the-box in Vray that would have taken you literal seconds to do in post.

[Ernest Burden III]

I'm sure we've all seen the Gamma 1 vs 2.2 grayscale image...

 

Gamma 1 is the bomb

[Francisco Penaloza]

Here is a quick test, I did used your giant light but I did reset all your rendering values and used my typical ones. Still can get cleaner result but this one render fast, how you can see there is enough range to play with this image, those very bright areas by the windows are typical of Linear color mapping but they can easily fixed in post if you keep the image in a float format.

When I get home I may setup the lighting by your lighting equipment to see how that work, pretty sure it will give more tone variance.

BTW I though this office what in the middle of the building, you have giant windows all over, enough to use some exterior lighting in your scene, also the office monotone palette won't give you too much color variance unless you put some love in post.

[landrvr1]

Your whole set up is going to fight any sort of contrast by nature of what you are rendering. Open space office/cubical farm plans have extremely even lighting in reality. You won't see much light contrast if you walked into that place when it is built in real life, so don't really expect anything to be eye-popping when you render.

 

I'm sure we've all seen the Gamma 1 vs 2.2 grayscale image.

[ATTACH=CONFIG]49791[/ATTACH]

Where in all of that glorious gray of 2.2 are you going to get contrast? The answer is in bestee's post.

 

 

 

You are going to spend days trying to get that 10-20% contrast out-of-the-box in Vray that would have taken you literal seconds to do in post.

 

 

Great comments.

 

I do realize that most office environments are going to have very even lighting at around 30 to 40 footcandles. The whole system is fighting to keep shadows away, lol.

 

I also just want to clarify that I'm trying to get as much contrast out of a raw VRay shot before post - in large part because my efforts sucked. Because my efforts sucked, the levels adjustment in post also started to dramatically affect the overall color/hue of materials - which was a very undesirable effect.

 

I think Francisco's new effort really shows that there's certainly more I can do to get a better starting point.

[landrvr1]

@Francisco, that looks really fantastic - much better results than my LWF efforts. Could you share your settings?

 

I look forward to also seeing your new lighting results.

 

Tnx much.