Help Topic: OCIO and LUT

[vlado]

I want to make a product suggestion in the wishlist forum to Vlado but still dont know exactly what I'm talking about.

Let me know when you figure it out. I myself would much rather prefer if people simply did this in post, as it is so much more flexible. If we put something in the VFB, it is very likely to be outdated next year when something else comes into fashion.

Best regards,
Vlado

[Oleg_Budeanu]

I think there should be response from Chaosgroup about what is this, why is it good/bad and why it should/not be implemented.
Looks like this requires some knowledge about how tonemapping is done, why Blender (for example) has option to change from sRGB to filmic tonemapping (that new fancy thing) and why actually it looks better after applying it
Now, when VRay sampling is adaptvie and we do not have headaches with irradiance map, adjusting materials subdivisions and etc - new things are poping out here and there, and i think that is normal.
I am quite sure VFB should not be overwhelmed with features and become new photoshop - you have separate software for this.

[LudvikKoutny]

Let me know when you figure it out. I myself would much rather prefer if people simply did this in post, as it is so much more flexible. If we put something in the VFB, it is very likely to be outdated next year when something else comes into fashion.

Best regards,
Vlado

The actual idea here is to look through it right when you work, so that you nail down your shading/lighting better than looking at it through raw sRGB. It's kind of nicely explained in that video, where he points out artists often create for example dimmer lighting to avoid things burning out. But then the amount of bounced light suffers, and in turn, realism suffers.

Otherwise, if you work in just linear, then you will most likely set up your materials and light to look good under linear, and when you apply actual tone mapping in post this will start to look bland

But a good start would be simply to allow us using OCIO and LUT at the same time in the same way we are now able to use sRGB and LUT at the same time

[Ihno]

If you were a Photographer (or film guy) you'd do much post work as well. Most likely you'd even photograph a color chart to be able to linealize your photo before post to get what vray gives you out of the Box... a linear image.
The point here is: Color correction tools are designed to work on linear images. And using them on non-linear images will make them act different and can also produce strange results. So, I see no reason for the "its modern/ its better" point. Since its definitely better to do the whole post at once! And not one part in the 3d package and another part in the compositing software.
Having that said, I'd find it useful to preview the post in the vfb. And maybe get some kind of a reference for the post.
Currently I use the VFB curves for that purpose and it never bothered me, though.

I find the whole OICO/LUT chaos also quite complicated. Probably due to the way the internet provides information: wrong, incomplete, hard to find.
Does anyone know a good tutorial/book or course to bring light into this?

[LudvikKoutny]

I did not deny that photographers do not do post work anywhere in my post(s). The specific way Filmic Blender actually goes about it is quite smart, it uses Filmic Log instead of sRGB and then applies filmic curve on top of that.

This is not about turning VFB into post processing package, this is just about viewing the data that you render in V-Ray in something that better translates V-Ray's shading and lighting for your eyesight. That is why camera manufacturers add response curves to their camera, so that once you capture a photograph, digitally, you get something that makes more sense to your eyes. Something that looks more like what you saw with your own eyes before you decided to capture it on a camera. And then most photographers bring it into Photoshop to stylize it to your liking. But that is not in conflict with having something better than sRGB as a base to look at.

I don't think this comes down to the "it's modern = it's better" assumption, but rather "it looks nicer = it's better" one

[Oleg_Budeanu]

I did not deny that photographers do not do post work anywhere in my post(s). The specific way Filmic Blender actually goes about it is quite smart, it uses Filmic Log instead of sRGB and then applies filmic curve on top of that.

This is not about turning VFB into post processing package, this is just about viewing the data that you render in V-Ray in something that better translates V-Ray's shading and lighting for your eyesight. That is why camera manufacturers add response curves to their camera, so that once you capture a photograph, digitally, you get something that makes more sense to your eyes. Something that looks more like what you saw with your own eyes before you decided to capture it on a camera. And then most photographers bring it into Photoshop to stylize it to your liking. But that is not in conflict with having something better than sRGB as a base to look at.

I don't think this comes down to the "it's modern = it's better" assumption, but rather "it looks nicer = it's better" one

Cannot agree more with this. And explained actually quite good !

[Rens]

What would be the downside to having a couple of OCIO presets compared to the controls? And technically you could encode all the colour transforms in OCIO so you wouldn't need both LUT and OCIO, correct?
But yes it would help to get more options for getting nice looks/colour transforms/luts directly into VRay without making things complicated and cluttered, which is the tricky part.

[vlado]

That is why camera manufacturers add response curves to their camera, so that once you capture a photograph, digitally, you get something that makes more sense to your eyes.

No, not really. The response curves happen because of the way the specific hardware (film or sensor) responds to light (that's why they are called "response" curves). From then on, digital cameras apply a number of post filters, some of which are controllable (sepia, saturation, face detection and skin enhancement etc.) I still believe the correct place for those effects is not the VFB exactly.

Best regards,
Vlado

[vlado]

And then most photographers bring it into Photoshop to stylize it to your liking.

Most professional photographers also use professional cameras. Those typically keep the amount of additional post-processing to a minimum and closely stick to the sRGB standard. Point-and-shoot cameras on the other hand, usually apply a liberal amount of processing internally to make images more appealing. I can assure you that this processing is way more complicated than some simple filmic tone mapping

Best regards,
Vlado

[LudvikKoutny]

I can't argue with that as I am sure you know a lot more than I do. That being said, I still think that viewing render result through something at least basically tonemapped really helps in the end. Every single scene I've done so far in past year or so turned out looking better due to working from scratch with some amount of highlight compression and contrast boost already in VFB.

[vlado]

The VFB already has enough control for the final look in my view; the curves allow to do practically any tone mapping you want. They can also mimic the filmic tone mapping if needed.

Best regards,
Vlado

[1funk]

You can actually use filmic-blender in V-Ray. Open config.ocio in a text editor and you'll see this:

[B]# VRay users should uncomment the Filmic views below as VRay doesn't permit Looks[/B]
#    - !<View> {name: Filmic Very High Contrast, colorspace: Filmic Log Encoding, look: +Very High Contrast}
#    - !<View> {name: Filmic High Contrast, colorspace: Filmic Log Encoding, look: +High Contrast}
#    - !<View> {name: Filmic Medium High Contrast, colorspace: Filmic Log Encoding, look: +Medium High Contrast}
#    - !<View> {name: Filmic Very Low Contrast, colorspace: Filmic Log Encoding, look: +Very Low Contrast}
#    - !<View> {name: Filmic Medium Low Contrast, colorspace: Filmic Log Encoding, look: +Medium Low Contrast}
#    - !<View> {name: Filmic Low Contrast, colorspace: Filmic Log Encoding, look: +Low Contrast}
#    - !<View> {name: Filmic Base Contrast, colorspace: Filmic Log Encoding, look: +Base Contrast}
#    - !<View> {name: Filmic False Colour, colorspace: Filmic Log Encoding, look: +False Colour}
#    - !<View> {name: Debug, colorspace: Debug}

So just remove the # from the start of those 9 lines

[1funk]

I also see some people confusing filmic tonemappers with this OCIO config. It's not the same thing.

Filmic blender is basically a log LUT with some preset OCIO "looks" (LUTs of custom curves) that are applied before the log LUT.

[^Lele^]

https://github.com/sobotka/filmic-bl...er/config.ocio

"

roles:
	default: Linear
	reference: Linear
	scene_linear: Linear
	data: Non-Colour Data
	compositing_log: Filmic Log Encoding
	color_timing: Filmic Log Encoding
	default_byte: sRGB EOTF
	default_float: Linear
	default_sequencer: sRGB EOTF
	color_picking: sRGB EOTF
	texture_paint: sRGB EOTF
	matte_paint: Filmic Log Encoding"

As seen from the OCIO descriptor, all you need is to apply the LUT you want in the VFB ("filmic" is no different than any other 3d LUT, this one's just in Sony's proprietary format.) in log space.
Nothing of scene data changes (as the author at least knows what he's doing, clearly, up to not messing with internal CM.), and the lin_to_log and log-space LUT application are done to the VFB, paired with a further contrast LUT to be chained afterwards (what he calls Looks: arbitrarily chosen contrast curves saved as 1d LUTs.).
What you end up is a Log VFB, with the Log curve de-contrasting character being brought back artificially, not through back-transform into linear but through 1D LUTs with fixed behaviours, which entirely breaks the screen linearity of LWF.

1. Filmic Log Encoding Base. This is the workhorse View for all of your rendering work. Setting it in the View will result in a log encoded appearance, which will look exceptionally low contrast. (it stays Log. ndr.)Use this if you want to adjust the image for grading using another tool such as Resolve, with no additional modifications. Save to a high bit depth display referred format such as 16 bit TIFF. This basic view is designed to be coupled with one of the contrast looks.

I've had to deliver two movies where the VFB was forced out of Display-Referred Linearity, and i would wish that as torture to my worst enemies only, and even then, not nearly for as long as i had to endure it.
There is no way -in my books- that anything as skewed as this, between UI and VFB, could become a default with V-Ray: might as well mess with the CC settings, and distribute something that works for one of your shots as a preset, expecting it to work right for every other render.

[stevejjd]

@Vlado - Thanks for your reply. I dont think Ill be figuring this one out any time soon. Its beyond me. I just dont like the gap between VFB and NUKE. Its like working blind. I wish there was a yat to just work with Vray in a way that you see the end result as you work. I think Im just going to have to get over it or learn. I'm self-taught and there is not much available in the way of professional training in this area. No one but the really pro studios truly know how and why to use OCIO, LUTs and so on. Ill never get it, its too much for me.

Excellent feedback people...So we just leave it to post? hahaha

So is the correct workflow of professionals to get the image as close as possible in the VFB and then do post work in Nuke? Or is lighting just blocked in quickly then composited?

What ratio of VFB to Nuke? for example, 80% of work in V-Ray and 20% in Nuke?

Should working in V-Ray be considered blocking in the lighting an materials for polishing in Nuke?

Is there any simple, convenient way that the post treatment in Nuke can be baked to a file that the VFB can read? ~ So that the scene can be worked on with the final look applied?

Are there any pro tutorials on how to properly lookdev characters in Vray and Nuke?

Thanks ~