Author Topic: HDR Lighting  (Read 21515 times)

2014-10-04, 09:30:58
Reply #15

fla

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@mp5gosu: peter guthrie and berntrand are changing gamma (or is it gain?) for quite some time now, based on their blog reports. So i the rest of the community. So I don't see anything wrong with it, results are great and so is the workflow (no need of positioning the sun to fir the HDR). But I wouldn't change anything besides gamma(gain) though!

@tomislavn: in does work in luminance channel in 1.1 if I'm not mistaken. Will try it out later.

cheers to both!
matej

2014-10-04, 12:32:53
Reply #16

mp5gosu

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@mp5gosu: peter guthrie and berntrand are changing gamma (or is it gain?) for quite some time now, based on their blog reports. So i the rest of the community. So I don't see anything wrong with it, results are great and so is the workflow (no need of positioning the sun to fir the HDR). But I wouldn't change anything besides gamma(gain) though!

As soon as you start adjusting HDR Gamma, you are manipulating the way they HDR lighting is cast. Let's assume an optimal, perfectly ranged HDR, with overcast sky. When using this as GI Source, you will get soft shadows. Now if you want hard shadows and you're using HDR Gamma, here are 2 points to consider: Overcast sky never creates sharp shadows. (To that point, you never want to deal with HDR gamma, but replace the HDRI with one where the sun is visible to achieve sharp shadows).
Secondly, if you decide to create sharp shadows adjusting the HDR Gamma, you have to keep in mind, that you do a curve manipulation which lead to results that highly differ from what it should be and what looks good. (I.e. crunching midtones, killing dark areas, etc.)
Btw: Good HDRIs always have linear color space and should be treatened like that.

But I have to admit, if you're using really low quality (low range or LDR) HDRIs, HDR gamma could make sense and helps to improve your image.
But in general, you should stick to high quality HDRIs, probably buy some good ones. Then you will not run into any shadow and accuracy issues most likely.

Oh and by the way: It's not entirely wrong. It's still up to the artist, to gain a decent style of lighting. Boosting shadows and bright areas can be done with gamma, but can also be done in post, with FULL flexibility.
« Last Edit: 2014-10-04, 12:42:00 by mp5gosu »

2014-10-04, 13:44:58
Reply #17

fla

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I agree on everything you've sad mp5gosu.
I use HQ PG HDRI images but there is still a need to make small adjustments in gama (somwehere in between 0.75 - 1) in order to get exactlly the right sharpness you want. Even if you use sunny-day HDRI. Offcourse there are alternatives (using sun or direct light) but they are a bit time consuming, but certainly doable.
I don't want to impose my method as the right one, I'm just saying there are HQ 3D artists that use this method and this is why I would love to recreate it in Corona too. I'm a vRay user ATM.
Here's his blog post about the issue: http://bertrand-benoit.com/blog/2010/02/27/on-hdr-lighting/
You could find Peter Gutrhrie's post on his blog too.

cheers
m


2014-10-05, 12:00:58
Reply #18

Rhodesy

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Can't you adjust this just using a c4d filter shader with the hdri loaded in?

2017-02-08, 11:14:52
Reply #19

chae

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Rotating the sky object works for me.

Unfortunately using the latest version for CD4, the rotating sky object doesn't work for me, what I found easier to do was select everything in the scene but the sky object & rotate those, check the render and shadows move as expected...not ideal but a quick work-around

Just testing the render engine and comparing it to Thea Render which I've been using for a wee while now...certainly a lot faster (I think) and love some of the features including the denoise...just got to get use to working with the materials in a different UI, though the Thea material selection UI is real nice, would be good to see something like that instead of going up to the contents browser, finding material then dragging it into the materials area...or am I missing something :)

Oh yes and the only dislike so far is seeing all those wonderful 3DMax material libraries for Corona and we can't use them at all without having to convert them :(

2017-02-08, 14:50:38
Reply #20

TomG

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On rotating an HDRI, the Offset U in the material tag would be used:

Let me know if that is not working for anybody!

2017-02-09, 05:02:30
Reply #21

chae

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Perfect - Thank you :)

Spoke too soon...When I modify the Offset U I can see the HDR rotating in the CD4 Viewport, but when I hit render in Corona the viewport shows the HDR in the 0 degree position/default loading...so what I see in the CD4 viewport HDR wise is not the same as the VFB...I've even hit refresh and erase several times re-rotated the HDR and yet the VFB shows no movement.
« Last Edit: 2017-02-09, 05:18:08 by chae »

2017-02-09, 14:45:55
Reply #22

TomG

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Hmm, not sure on the cause of that, all is working here - the set up is a Sky object, with a Corona Material applied, with the HDRI in the Diffuse slot? Just checked in a simple new scene, and the update happens in the viewport, the C4D picture viewer, the rendered viewport and the Corona VFB. Also works if I set keyframes. Can you share the scene, or a simplified version of it?

2017-02-09, 20:31:17
Reply #23

chae

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Hi Yah Tom,

Just prior to knocking off for the night yesterday, I uninstalled Corona, reinstalled then pulled up the model I was working on. The model had already been rendered prior in Thea, so what I did was remove all materials, camera settings etc etc and started with a bare model, applied a general corona diffuse material to everything, recreated the sky as per movie and now everything's working as expected !!!

So not sure if it was the reinstall, or something carrying over from Thea but what I'll do is pull up some more models I've worked on and see what happens.

Thanks for getting back so quick :)

2017-02-09, 20:45:09
Reply #24

TomG

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Glad to hear all is working now! NP too, just glad it helped resolve it!

2017-02-10, 22:00:34
Reply #25

sht

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why don't you just rotate the sky object. It's much more intuitive to me.

2017-02-15, 05:11:42
Reply #26

arail

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Thanks for that video - real helpful, real clear.
I'd like to see 50 videos like that - each 5 to 10 minutes long. A list that a user could access and get a quick primer on a subject when needed.

2017-02-19, 02:08:49
Reply #27

mrittman

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Is there a way to adjust the HUE value of an HDR map? I have an HDR map I like, but would like to remove some of the green that it contains.

2017-02-19, 16:50:29
Reply #28

Nejc Kilar

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Is there a way to adjust the HUE value of an HDR map? I have an HDR map I like, but would like to remove some of the green that it contains.

Put it into a "filter". You know, click the arrow by the name -> filter :)

Hope thats whats you meant.