Author Topic: HOWTO: Calibrate "HDRi with Clear Sun" to "Corona Sun/Sky"  (Read 31948 times)

2016-05-11, 12:46:16
Reply #30

James Vella

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reading again i see what your saying juraj lol. You are correct i misunderstood. Thanks for the clarification.

Im very keen to see these new hdri from Peter. Im curious though why they come in over bright and need to adjust them compared to others like episcura? Edit- u answered this time for testing..
 
Nice tutorial btw dubcat. I need to re read your posts 3 times before i can grasp your workflows, ur a mad man =)


2016-05-11, 13:12:13
Reply #31

Juraj Talcik

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I am using relative EVs exposure (just artistically, not exact match to real world cameras), so I adjust Peter's HDRi into 0.01-0.1 multiplier (I am using VrayHDRi loader) so I can see them exactly as other industry-standard HDRis :- ).

Using HDRi with low multiplier and high exposure or high multiplier and low exposure is ultimately the very same result. But having HDRi base exposure matching real-life exposure makes it easier to match to artificial light fixtures.
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2016-09-06, 03:37:40
Reply #32

Njen

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Jumping in late here, I'm surprised no one has mentioned Terragen yet. As someone who has processed over 100 HDRI's for the VFX company I work for, I've seen my fair share of photographic and fully digital HDRI's. If we need clear to partially clear skies to light with, a spherically rendered Terragen HDRI produces near perfect results to actual photoreal, even better than photograpic captures that have been processed. The sun values are exactly what they should be with and render perfectly in Corona and there is no need to edit in PS or Nuke. At my company, we now use Terragen created HDRI's in more than 50% of our renders, even if the client has supplied us with photographic HDRI sets for us to process. Save the money that you might spend on photographically captured HDRI's and buy a Terragen license.
Please support my Kickstarter for my animated film, Cyan Eyed (rendered in Corona)!

2016-09-06, 08:48:33
Reply #33

romullus

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I wonder, how Terragen generated HDRI of clear sky can be better then native sun&sky system in Corona?
I'm not Corona Team member. Everything i say, is my personal opinion only.

2016-09-06, 09:02:58
Reply #34

Njen

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Because you can have all of the realistic looking clouds in there too.

[Edit:] Hmm, i obviously missed your point about a 'clear' sky. And I'd say it's comparable, though I have found that Terragen's colour reproduction of light in the atmosphere and of the colour of the sun to be the closest I've seen to looking real. But regardless, the second you need some clouds in there, Terragen is the best solution.

[Edit 2:] My comment was responding to the fact that if you have to do any image editing to get a HDRI to react properly, then why not do it properly once using a piece of software specifically designed for the task.
« Last Edit: 2016-09-06, 09:12:40 by Njen »
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2016-09-06, 09:22:11
Reply #35

Njen

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Here's an example HDRI generated from Terragen that took me about 10 minutes to make, and has all of the dynamic range needed to light properly with, with no need to do any image editing afterwards. Originally rendered at 8k.

[Edit:] For those who are interested, this HDRI was created to be used in my steampunk themed animated short film that is being rendered with Corona. Check out the website www.cyan-eyed.com and follow us on www.facebook.com/Nezui/ for more information!
« Last Edit: 2016-09-06, 09:39:05 by Njen »
Please support my Kickstarter for my animated film, Cyan Eyed (rendered in Corona)!

2018-08-03, 23:34:20
Reply #36

ynotsop

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Forgive me, I am new to Corona but... is the end result any different than simply deleting the sun in the original HDRI in Photoshop, loading up the original HDRI into 3ds max and aligning it with Corona sun and then simply replacing the original HDRI with edited (no sun) HDRI?

2018-08-04, 01:15:38
Reply #37

dubcat

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is the end result any different than simply deleting the sun in the original HDRI
Same thing :)
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2018-08-20, 14:40:37
Reply #38

ynotsop

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is the end result any different than simply deleting the sun in the original HDRI
Same thing :)

Hey dubcat, let's say I am using CoronaSun linked up with and HDRI and one of the materials from the Corona library. How much do I need to lower the exposure of the sun to get a correct looking material? Is it -4.0? Or should I rather lower the sun intensity?

I am trying to figure out the correct workflow.