Help Topic: OCIO and LUT

[stevejjd]

Hi
I need some help regarding OCIO and LUTs.

I dont know anything about color grading, I just want my renders to look photogenic instead of raw.

Is some one able to explain how to properly use OCIO in the V-Ray frame buffer?

I downloaded the OCIO Zip from http://opencolorio.org/

and loaded it into the frame buffer.....from this point I am confused.

Is there some profile I can load that makes it look filmic? ~ and how would I do that?

Thanks



**** UPDATE *****

I have always wanted Vray to look filmic with its renders instead of raw.
I did some research and found that companies use NUKE to treat the renders and make it look filmic.
Is it better to do look dev raw and then apply treatments later in NUKE?

What is the best workflow for a character look-dev artist in regard to LUTs, OCIO and ICC?
Are there any profiles that make the raw frame buffer image look like natural film?


Please have a look at this "Filmic Blender" I found;
http://www.blenderguru.com/tutorials...-photorealism/
https://sobotka.github.io/filmic-blender/

So apparently they are adding an OCIO profile to the rendering and I would like to do a similar thing inside of 3ds max + V-Ray. Is some one able to tell me how to set that up?

[LudvikKoutny]

It's been a hot topic lately, and while the video is full of inaccuracies, the main point he is making is right.

You can't really apply this workflow in V-Ray unfortunately, as that would require ability to use OCIO and LUT at the same time. If you enable OCIO in V-Ray VFB, you can not then use LUT. Also, V-Ray does not have ability to bake these transformations into output file.

[stevejjd]

Thanks for your reply. I had no idea how complicated this stuff is....its crazy.

Please may you take the time to look at this;

https://knarkowicz.wordpress.com/201...mapping-curve/

I think maybe what Im asking for is a new Colormapping mode. Vray is set to use Reinhard for linear workflow. Is it possible to make a "filmic" tone mapping one based on something like the ACES Filmic Tone Mapping one?

Can Chaos Group just copy a Nikon, Canon, Leica DSLR's film response tone mapping curve? ~ I dont know how to do it but I just want a better look that Raw rendering. I dont have enough time or money to get nuke and learn it. Please just make a new button for me that makes it look like a photo or film.

I dont really understand LUTs, OCIO, ICC and on and on and on....Is it possible to have in Vray what blender has ~ a filmic tonemapping option?

Kind regards

Steve ~

[LudvikKoutny]

I actually brought this up on other forum, but did not mention it here, as Chaosgroup is usually quite slow to adapt modern standards. I guess we will eventually have something to accommodate for this modern workflow, but it will probably take around 3 years Significant portion of the userbase is quite conservative and orthodox, so revolutionary improvements are usually met with mixed feelings instead of warm reception.

[kosso_olli]

I really like some of the ideas of the filmic tonemapping. But keep in mind that all of this still has to work with complex compositing setups, deep data etc.

[stevejjd]

I actually brought this up on other forum, but did not mention it here, as Chaosgroup is usually quite slow to adapt modern standards. I guess we will eventually have something to accommodate for this modern workflow, but it will probably take around 3 years Significant portion of the userbase is quite conservative and orthodox, so revolutionary improvements are usually met with mixed feelings instead of warm reception.

Yeah I see what you mean. Its very strange that Chaos Group gets 10/10 for listening to feedback and yet is conservative and orthodox.

Should I make this a new thread in the product suggestion forum?

If V-Ray doesn't have filmic tone mapping then how to you apply a filmic treatment to a raw image? ~ What is the work around to make it look like a photo without making it look like instagram?

[LudvikKoutny]

I did not meant it as a bad thing. Chaosgroup definitely listens, it just that the changes have to be performed a lot more carefully, because they affect a lot more people, and they affect also big studios that turn around big money. This, in turn, slows down some doing some controversial decisions, which mean changing of old, established standards.

The thing to keep in mind is that Blender people see it as revolutionary because Blender Cycles had no reinhard/highlight compression at all. You got only linear, or custom curve. While we, V-Ray users, did not need this nearly as much as V-Ray, because there was always reinhard tone mapping for us, which does something similar to filmic. Filmic is just evolution, improved reinhard, but reinhard already does a fairly good job.

Some years ago, I noticed that it is really difficult to transfer material properties from photograph into VrayMTL settings by eye as long as what you see in VFB is just sRGB output without any tone mapping. Camera pictures always had a bit more compressed highlights and at the same bit more contrast. So I would be stuck in endless loop of little material tweaks because I could not get the material behaving exactly like on photo, even if my light setup roughly matched the one on that photo.

Then it clicked - camera response curve was missing piece of the puzzle. So ever since that, when I create a new scene, first thing I do is to set up my tone mapping to roughly simulate some camera response curve. For some reason, actual curve color correction in VrayVFB works in really weird way, so I use just basic exposure settings, these:

It will not give you Filmic/ACES curve, but it will give you something that's fairly close, and will make your life easier when it comes to both setting up scenes, and matching scenes to real world.

[stevejjd]

Yeah totally ~ for sure. I think Chaos group has the right balance.

By the way I found this https://vimeo.com/ondemand/tonemap

apparently is a far better workflow to render raw images a wide dynamic range and then tonemap in post.

I guess I'm just confused as to how to light, render, lookdev my scene. I'm stuck between making it perfect in the frame buffer or making it perfect in post.

After some research, I think its a bad idea to have filmic tonemapping within the render engine because it compresses the dynamic range of the image.

The Filmic tone-mapping would have to be done via the frame buffer as a post effect.

Maybe a tone mapping configuration could be made in Nuke and the exported into VFB just like a LUT file. It would be a non destructive way of applying tone mapping so that you can turn it on or off as you lookdev.

[Rens]

So this filmic thing is just a LUT? That blender page makes you believe all current renderers are broken.

[stevejjd]

So this filmic thing is just a LUT? That blender page makes you believe all current renderers are broken.

Im reseaching now....actually the solution could be extremely simple! ~

Filmic Tonemapping is definetly NOT LUT.....its really amazing! ~ I actually think that the frame buffer can do this as it already has super basic tonemapping controls......They just need to update them!!!

CHAOS GROUP PLEASE ADD THESE CONTROLS .... THEY ARE BETTER THAT EXPOSURE CONTROLS

Here are the filmic tonemapping controls in Fusion. It gives so many controls over the highlights and shadows.




So Chaos group dont need to build an internal filmic tone mapping type of Color Mapping....just update the controls on the frame buffer with this filmic tone mapping contollers
https://corona-renderer.com/forum/in...p?topic=1807.0

Can we please have the controls as seen in the attached image for Vray ? PLEASE! haha



*****UPDATE*******

Im going to make this into a feature request but we want the Nuke style Filmic Tone Mapper controls for the VRay frame buffer
https://corona-renderer.com/forum/in...13558#msg13558



This is the Nuke controls. I think the Nuke and Fusion controls are essentially the same.

[Rens]

Ah ok, so yes it's a colour correction/LUT with controls, the difference is that the Reinhard and sRGB examples are baked into the render. So technically you could apply this on a linear exr render in post as well, yes?

[stevejjd]

Ah ok, so yes it's a colour correction/LUT with controls, the difference is that the Reinhard and sRGB examples are baked into the render. So technically you could apply this on a linear exr render in post as well, yes?

Yes the workflow is to
- Set V-Ray and 3ds max to use Linear Workflow. The color mapping should be Reinhard with a burn value set to 1.0 and mode to none (dont apply color mapping) and Gamma 2.2. Use the V-Ray Render Setup > Frame Buffer and chose V-Ray raw image file
- Render out 16bit or 32bit .exr images because of huge dynamic range
- In Nuke or Fusion apply the filmic tone mapping which controls the highlights and shadows.

My idea is that instead of the super basic exposure and hilight burn controls in the VFB why not have the filmic controls? Would be amazing!

[LudvikKoutny]

Some things should be set straight here:

- Saying that it can be done in post is completely missing the point. The entire point of this is that you do not do this only in post. That you view your scene through better camera response already when setting it up, so you don't make mistakes in setu process, such as using too faint light sources that will cause less light bounces, and such. The point of this is viewing data that renderer feeds you through a curve that makes the data more resemblant of how human eye perceives real world captured through photography. The point here is to prevent you working blind the entire time in 3d package, and hoping you will fix it all in post.

- Yes, it is a LUT, technically, but LUTs can not access more than 0-1 range, so that LUT needs to be fed the source image in a Filmic Log base, instead of sRGB base, so it can access entire exposure range, not just 0-1. And this is something V-Ray can not do. V-Ray can load the Filmic Log base OCIO, but it does not allow you to use OCIO and LUT at the same time.

- It would be very unfortunate to implement ACES in a way that it exposes all of the filmic tone mapping controls. All the toe/shoulder and slope parameters. This would confuse the hell out of users, especially the new ones, and would kill the feature almost instantly. The simplistic way it is implemented in Blender is a lot better example.

I would recommend this video. It's more professional and technical than BlenderGuru's video. It has a lot less inaccuracies and explains it a lot better: https://www.youtube.com/watch?v=vKtF2S7WEv0

[stevejjd]

Excellent, Thank you for your feedback. I'm still figuring this stuff out. I want to make a product suggestion in the wishlist forum to Vlado but still dont know exactly what I'm talking about. Ill have a look at the video. Thanks

@Recon442 Can you please help me write the product request?

[LudvikKoutny]

Well, I myself still don't have clear idea about the most easy to use and intuitive way of ACES implementation, so I need some time to think about it