Author Topic: dubcats secret little hideout  (Read 100819 times)

2018-08-23, 21:37:51
Reply #270

dubcat

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The Canon 5D Mark I (classic) always had something special in the color rendition.
Hey!

Here is the RGB version of the LUT. It actually brightens 0 RGB, quite interesting.

Hey Dubcat.

Hey man!
I see oddvisionary has been kind enough to answer when I was afk. I would use your sculpting software of choice and Painter.
I would also generate an IOR map from the normal map, since this model would be fictional and not based on specular scans.
You need the IOR map for micro shadowing like here:



Hi dubcat, I got into hdri calibration thanks to your tips thank you! However I would like to somehow calibrate hdri that has partially overcast sun - is that possible in any way? or is it just eyeballing then? for example some of noemotion evening hdris so that the intensity of direct light would be correct

Hey!
If the sun is blocked by clouds and the HDRi provider does not include a grey card reference, we just have to guess. If you give me a link to one of the HDRis you have in mind, I can take a look at it.

If you are interested in getting real world values, you can do this:

- Go outside when it's cloudy.
- Place a ColorChecker grey card on the ground.
- Take a photo of the grey card.
- Recreate the grey color material. If you use a ColorChecker Passport, the grey bellow yellow is 19.8% linear (122 sRGB). (A grey sphere would be best, since you can capture F0).
- Create a camera with the same settings you used on the real camera.
- Calibrate your HDRi until the real and digital color checker match in values.

Before doing that i want to be sure that i won't do any irreversible damage.

Hey man!





My guess is that the HDRis you tested already had low sun values, that are bellow Photoshops clip value. If you add 7 +20 Exposures in Photoshop above a 255 RGB layer. You will go above the threshold and it turns black.



I've attached the Corona Sun/Sky HDRi saved from Corona, if you want to do tests on that one.

edit: fixed typo, i meant specular not spectacular :p
« Last Edit: 2018-08-24, 03:01:05 by dubcat »
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2018-08-23, 21:48:16
Reply #271

Basshunter

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Thanks for your answer @dubcat

2018-08-23, 22:14:16
Reply #272

pokoy

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Quote
You will go above the threshold and it turns black.

You had one job, Photoshop. Someone should tell Adobe it's 2018 already *facepalm*

2018-08-24, 07:21:44
Reply #273

siebe

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Hey!

Here is the RGB version of the LUT. It actually brightens 0 RGB, quite interesting.


Thanks! you are the best :)

2018-08-24, 07:44:37
Reply #274

subpixelsk

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For example 03-29_Sunset from noemotion if you wouldn´t mind :) thanks a lot


2018-08-24, 09:29:40
Reply #275

romullus

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My guess is that the HDRis you tested already had low sun values, that are bellow Photoshops clip value. If you add 7 +20 Exposures in Photoshop above a 255 RGB layer. You will go above the threshold and it turns black.

Ah, that might be the case indeed. Good news that you can't ruin HDRIs that are already ruined :]
I'm not Corona Team member. Everything i say, is my personal opinion only.

2018-08-24, 14:25:22
Reply #276

Basshunter

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Hey dubcat,

Do you think there's any way to guess the albedo color of an object (In this particular case a wood floor) from just reference photos (Low quality) with different light conditions?

2018-08-25, 11:14:45
Reply #277

romullus

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I would also generate an IOR map from the normal map, since this model would be fictional and not based on specular scans.
You need the IOR map for micro shadowing like here:

Hi dubcat! Would it be too much to ask if you have normals to IOR photoshop action and are willing to share it? I know that you already gave us specular to IOR and roughness to IOR actions, but one of them doesn't work for me and the other one doesn't give as good result as i hoped for (likely because i'm doing something wrong). I have a feeling that normals to IOR might be what doctor prescribed :]
I'm not Corona Team member. Everything i say, is my personal opinion only.

2018-08-27, 14:46:49
Reply #278

romullus

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My guess is that the HDRis you tested already had low sun values, that are bellow Photoshops clip value. If you add 7 +20 Exposures in Photoshop above a 255 RGB layer. You will go above the threshold and it turns black.

So what would be solution to editing/saving of full float EXRs? I have some 8K 32 bit displacement maps that i would like to downsize to 4K and resave, but can't figure out how to do that. Photoshop is no go, my beloved small app Picturenaut is as bad if not worse. I even tried to use 3ds max slate editor's option to render map and save to exr, just to find that it clips everything to 8 bits *sigh

Is there some app that can edit and save 32 bit files in a proper manner? Preferably free or low cost one.
I'm not Corona Team member. Everything i say, is my personal opinion only.

2018-08-27, 14:53:33
Reply #279

Juraj Talcik

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Affinity designer has superior 32bit environment capabilities compared to Photoshop. They really outdid Adobe at this.
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2018-08-27, 15:19:54
Reply #280

romullus

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Thanks for the info! Downloading trial now.
I'm not Corona Team member. Everything i say, is my personal opinion only.

2018-08-27, 17:09:51
Reply #281

burnin

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Is there some app that can edit and save 32 bit files in a proper manner? Preferably free or low cost one.
PhotoLine (59 €)
GIMP (FOSS)
Picturenaut HDR maker & tone mapper (FOSS)

2018-08-27, 19:48:45
Reply #282

romullus

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I'm getting odd results here. Even though Affinity exports fully retained dynamic range, the results i'm getting from original and resaved EXR's, are quite significant. But strangest thing, that Affinity's exported displacement map is giving better result than original, i.e. comparing low-poly model renders made with original displacement map and with resaved in Affinity one to high-poly render, then latter is much closer to real thing. What the...? Both textures outside of 3ds max looks pretty much identical, but max treats them differently. So much for care free 32bit displacement rendering... :/

@burnin, thanks i'll look at your links, although i can already dismiss Picturenaut, as it's completely unsuitable for work with full float formats and has almost no editing capabilities. However it is still great as a HDR viewer.
I'm not Corona Team member. Everything i say, is my personal opinion only.

2018-08-27, 19:52:34
Reply #283

Juraj Talcik

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That is very strange, could it have done some interpolation perhaps ? Do you get different result even if you simply open and export it, or do you have to resize to produce the differences.
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2018-08-27, 20:05:03
Reply #284

romullus

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My initial reaction too was that it might something to do with interpolation, therefore i did remaining tests with unchanged size - just opened image in Affinity and resaved with different name. Somehow i think it's more 3ds max's fault than Affinity's. Original file is single channel and Affinity save it as RGBA. Resaved file is getting slightly bigger in size (not by much). But strangest things happens inside 3ds max. Max's bitmap loader reports original file as 32bit greyscale, but once loaded in slate editor it has populated all 3 channels with data, however when it loads Affinity's file, it reports it as 32bit RGBA, but in slate editor it has only red channel populated!!! I even tried to change max bitmap to Corona bitmap or even another renderer, but results always is the same, i.e. - different displacement.

I can share a link to that particular asset, if someone is interesting to give a try to this mystery.
I'm not Corona Team member. Everything i say, is my personal opinion only.