Author Topic: HOW TO: Make a Calibrated Material Scene  (Read 21890 times)

2017-10-13, 16:39:58
Reply #15

arqrenderz

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Me and my mom doesn´t  have that hdri :( were can we find it??


2017-10-13, 20:24:07
Reply #17

dubcat

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Can you explain me why it is important to desaturate the HDRI with a color correction node together with desaturating the VFB.

It's just in case people don't desaturate the HDRi :)
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2017-10-26, 08:57:26
Reply #18

James Vella

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Thanks Dubcat, this made a big difference to some of the balancing issues I was having!

2017-10-29, 03:52:03
Reply #19

shortcirkuit

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so correct me if I am wrong, this exercise is to get the lighting vs albedo on textures correct?   By putting the DE SATURATED HDRI in the environment slot, the grey 18% will be consistent across the scene and all colors should be quiet accurate.  You must also used the normal HDRI in color and put them in all of the overrides (reflection, refraction + direct visibility).  Correct?

Also, in terms of the process, the way i understood is to put the sphere in the middle of the rendering viewport and ensure the brightest part (lets assume a sunny exterior HDRI from peter guthrie) is right in the middle of the sphere.  SO if you were to change the grey 18% material temporarily to a CHROME reflective ball, the sun should be right in the centre of it and that is where you sample your values from (but ensuring you change it back to grey 18% of course).
Is this all correct?

Thanks

2017-10-31, 15:39:48
Reply #20

dubcat

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Hey

Quote
Correct?

Spot on.

Quote
temporarily to a CHROME reflective ball

Smart idea!

Quote
Is this all correct?

Yes.
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2017-10-31, 23:39:52
Reply #21

shortcirkuit

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awesome thanks for clarifying - very much appreciate your efforts and knowledge mate!

2017-11-24, 20:13:48
Reply #22

dj_buckley

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I genuinely don't get the point of this?  Can someone explain why you would do this?

I keep seeing 'turn on a LUT' to see the final rendering.  Isn't whatever is in the frame buffer the final rendering?

I am having an issue with images generally looking quite flat in Corona frame buffer, maybe this is what I'm missing?

Apologies for the basic level of understanding

2017-11-24, 23:16:08
Reply #23

dubcat

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When we use real world albedo values stuff will look flat. Real camera raw files look just as flat. So we have to enable a LUT or crank the contrast slider to get a processed image look :)
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2017-11-25, 00:15:21
Reply #24

dj_buckley

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Makes sense, i think i’ve been using a mix of albedo maps and standard textures which could be the cause of my headaches.  I guess as soon as you go down the albedo route, all your textures/colours need to be in line, otherwise you’ll have some very oddresults as i did recently

2017-11-25, 00:23:15
Reply #25

dubcat

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Here is a Photoshop script I made to convert non albedo maps over to albedo. It uses "Apply Image" to make a 1:1 split, and the "highpass" layer keep all the hue variation. You just have to change the albedo color to a proper color, and maybe reduce the contrast on the highpass layer, if the original map is way off.

I use this method all the time to fix old foliage to megascans.

You can do this in corona too, like this.
This should be an official corona map if you ask me! It's so good on glossiness maps.

« Last Edit: 2017-11-25, 01:58:34 by dubcat »
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2017-11-25, 16:28:47
Reply #26

dj_buckley

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Ok, so that just leaves me to ask - what's the point in all of this?  Is it purely to suit other workflows?

It seems to me that all we're ultimately doing is removing contrast, just to add it back in?  Take a nice contrasty texture, flatten it, render it, add contrast back in using the frame buffer?

What have we been doing up until this point?

Also I have another question regarding the frame buffer, was/is VFB the same as CFB, I never seemed to have to as much 'post work' in the frame buffer with VRAY to get a nicer looking result, but that could be because I was using textures that i'd already edited to look good in the frame buffer.

It just feels like a bit of a convoluted workflow just to aid the pursuit of 'physical correction' something the end client probably isn't going to notice or appreciate right?

2017-11-25, 19:51:25
Reply #27

Juraj Talcik

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Are you commenting on the last post purely ?

That doesn't concern contrast outside of correction if needed. It gives you the flexibility to real-time adjust albedo(color) of any texture. Highpassing separates "Color" and "Detail" into two separate parts. I do this in Photoshop, with map like above, it could be done automatically.

Regarding Corona buffer and Vray buffer, yes, they are very much identical. Their tonemapping are actually exact copies of basic Reinhard just with different control (Vray inverted/remapped 1-99 into 0-1 range).
Both renderers benefit (or require) the same kind of post-production for different look.

If you are satisfied with how your renders look in framebuffer than I don't see what is your problem with.
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2017-11-25, 23:47:34
Reply #28

dj_buckley

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No apologies - i was querying the use of These flat Albedo textures in general as opposed to just using internet/camera sourced diffuse maps as we have done for years.

What’s the end goal? Ultimate control?  To get as true a raw image as possible when compared to how a camera/our eyes work?

I just wrapping my head round the whole PBR thing

2017-11-26, 08:07:27
Reply #29

James Vella

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Correct me if Im wrong, I have been following this with great interest and as for my understanding dj_buckley, the point is to have a color managed workflow. For example - if you have followed the above and calibrated your HDRI correctly, then straight into the frame buffer your Dulux colours should match 1:1 in the lit areas of your scene (I certainly get asked repeatedly by clients is this the EXACT hue/value, it looks about 5% darker than it should be?). Since following this I have had to do no additional post work to correct for this slight difference.

Im still wrapping my head around this part (separating the albedo) but Im guessing it ties into the first part of this tutorial, you can then place the exact colour of timber (in this case) on your boards that your client has requested and know that its going to be the exact colour they have requested. You are then free to use the textures you always have however change the colour on the fly, I can already think of other instances where this would be useful but just that alone is enough to sell me on the idea - not to mention I love workflows that incrementally make my life a lot easier.

Thanks again dubcat, your constant research has inspired me to keep digging and learning the finer parts of what I have ignored in the past due to my ignorance of - "well it looks pretty close" and then working my ass off on that last 5% in post anyway.
« Last Edit: 2017-11-26, 09:26:43 by James Vella »