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Grey 18 workflow

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Grey 18 workflow

Post Fri Dec 11, 2015 10:18 am

hi there

I have been preparing a tutorial about recent changes added to YafaRay by David and how I use them for my lighting workflow. It is a work in progress, I intend to add more chapters about testing conditions, outdoor lighting, simulating SRL response curves, editing work, etc. I hope you like it.

http://www.yafaray.org/node/667

Greetings
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Samo
 
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Re: Grey 18 workflow

Post Sun Jan 22, 2017 5:58 pm

I have added a tonemapping section to my Grey18 tutorial, please take a look.
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Re: Grey 18 workflow

Post Fri Mar 30, 2018 9:06 am

Scene using this workflow
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Re: Grey 18 workflow

Post Sun Apr 01, 2018 11:57 am

This is great! I'll check asap.

Have you tried with filmic?

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Re: Grey 18 workflow

Post Sun Apr 01, 2018 6:43 pm

Filmic is just a marketing buzzword IMO. Nobody is able to explain well why it could be good for my work, for instance this tutorial, which is pure no sense. I don't know whether to laugh or cry about the constant mixing of completely unrelated and badly explained concepts in order to arrive to the desired conclusion. Also some of the things explained there are plain wrong IMO, for instance all the stuff about photography or color spaces. I wish the author itself of the filmic feature could explain his work.

Last time I checked it, filmic is not among the standard space colors recognized by the ISCC. I still don't know why is in the color space tab when it is not a space color but just a tone mapping workflow. BTW, in the work posted above there is already a film like s-curve applied to the render, like I have explained in the Grey 18 tutorial. I also believe that digital cameras don't use static curves for 8-bits encoding, so I don't see why a static tone mapping workflow can be a good idea.

At the end, if somebody is serious about realistic rendering IMO he or she should take his digital camera out, set it in manual mode and start metering the world around, and look at how the camera software is mapping tones into 8-bits encoding with histograms etc, and find serious readings about the matter, like this one:
http://www.normankoren.com/digital_tonality.html
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Re: Grey 18 workflow

Post Sun Apr 08, 2018 12:41 am

I have tested the filmic view transforms with both Yafaray and V-Ray. I find them to be very useful. It is practically useful and not just marketing.

It is true the blenderguru tutorial includes some significant factual errors.

The filmic view transforms are based on ACES:- http://www.oscars.org/science-technolog ... jects/aces

It doesn't change your rendering process, it changes the way the rendered data is displayed on screen. There is quite a bit more to it, but basically, instead of clamping the data between the sRGB gamma 2.2 0 - 1 range, you get a wider dynamic range which is then tonemapped to the display range. I find the results appealingly photographic and also useful at the compositing stage. (It is true that simply saving to .exr presents the artist with more data for compositing, but it is display linear, where the .exr with the filmic transform is scene linear.)

Unfortunately, the current Blender implementation has removed the log view and now applies the Base contrast by default. In my opinion this was a mistake.
Bartek Skorupa describes that well here (from about 20mins) - https://youtu.be/kVKnhJN-BrQ

Alex Fry made an interesting presentation on using ACES transforms for the Lego movie. The features he describes here also apply to the filmic transforms.
https://youtu.be/vKtF2S7WEv0

. . . but I'm guessing you are already aware of all of this :)

There is a Blender Stack Exchange chat where you can discuss with Troy and others if you need more detailed information. It is sometimes quiet, but can be quite lively when discussion is in progress.
https://chat.stackexchange.com/rooms/34 ... abbit-hole
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Re: Grey 18 workflow

Post Mon Apr 09, 2018 10:24 am

I am still sceptical for several reasons. First it is a static workflow, I don't know how is mapping what and worse I can not edit it. I suppose that now it is just a preset intended to make peoples life much easier, like when people uses a automatic preset in their digital cameras so pics exposure always "look" right. It is also a way to stop people using linear tone mapping into 8-bits by default.

I prefer working with curves to approximate 8-bits encoding of non-HDR digital photography, which assumes neither unlimited nor unclipped range. In other words, since I don't shoot for HDR photography, I am always assuming limited range and shadow clipping in my work, and sometimes I look forward to it because it focuses the composition. My DSRL camera will only map about 6 EVs into 8-bits encoding depending on the lens, so this is the range I get to simulate in renders. No digital camera is going to automatically map 15 EV into 8-bits encoding like Andrew is implying, they will tell you to use bracketing and RAW editing for that, and you will end getting the usual HDR look which I don't like.

I generally use a s-curve for for film like contrast plus 'exposure' curves on a scene with coherent materials, f.e. those are tested before against a neutral middle gray. It is like exposing for highlights in a camera. Notice that film like s-curves can use long horizontal ends so you can simulate compression of lot of extra range in both ends of the 8-bits histogram, like some films did in the past. At the end is how that extra range is simulated what really matters, since the central range more or less stays the same. I don't like what filmic does to whites and bright tones since many times I like keeping them in the very edge of the histogram, I like manual control and I like shadow clipping very much, so I guess it is a matter of preferences. Also color saturation is a very subjective question for a preset to handle.

Afaik ACES is neutral encoding, the main feature is to preserve an active non-destructive link between linear shooting and finalist space colors and keep the transformation work done available for re-mastering. Gamma 2.2 in sRGB space is not limiting range in any way IMO nor has to do with CRT monitors, is transforming it so it works according to the human eye capabilities.
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