Author Topic: Using multiple HDRI's for lighting.  (Read 1788 times)

2018-11-09, 16:31:59

Xntric

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Is there any way to use multiple HDRIs environments maps for lighting up an object?

Then i could control the light from each hdri with lightmixer in post.

If not, the solution must be to make multiple renders and then blend them together in photoshop afterwards, but it would be nice if I could it in 1 render.

2018-11-09, 16:37:37
Reply #1

sequana

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+1

To be honest, i love Corona, but i have no clue why there is no dome. Especially for fast LookDev its a must have to set up multiple HDRI and then blend them easily. The funny thing is, its already working with sun and sky system but not with HDRI. I hope this will get changed at some point.
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2018-11-09, 18:15:36
Reply #2

sprayer

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You can draw lights in hdri in plugins like HDR Light Studio, and even more, you can place reflection directly at your model similar to keyshot

2018-11-10, 06:39:38
Reply #3

oddvisionary

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In max I'm using as many HDRI as I want using the slate editor :

- Import your HDRI using the CoronaBitmap
- Add a Corona_ColorCorrect map > Link it to the Scene Env map in Render Setup
- Plug each HDRIs in your correct Corona_ColorCorrect map to switch between as many HDRIs as you want + control gamma intensity etc if required.

That's for the look dev part. For the LightMix, I did not tried anything yet, not sure if it's possible since it will have to Render "behind the scenes" each HDRIs.
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2018-11-11, 01:41:23
Reply #4

Xntric

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Yeah, the thing is that I want multiple hdri lighting the object at the same time in the render.

2018-11-11, 09:21:31
Reply #5

oddvisionary

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multiple hdri (...) at the same time in the render.

Using the slate editor, there is a way to mix them, in some kind of multiply/additive mode. Give it a try with a mix texture or something.

I don't understand why you want them "at the same time". You can switch between them in 2 mouse clicks, in 2s.

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2018-11-11, 11:11:15
Reply #6

PROH

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Hi. This has been discussed several times before on this forum, and the bottom line is, that the lightmix can't handle more than one environment at the time. The same goes for the sun and daylight systems, and for background images.

It can however handle a bunch of different direct lights used as "sun", but this won't give you a physical correct environment.

Hope it helps.

2018-11-11, 15:55:40
Reply #7

Xntric

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Alright, I hope they will add in the future though.


2018-11-11, 16:00:42
Reply #8

Xntric

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and the reason why I want to render with multiple HDRIs, is that I want to have each HDRI as a render element so that I can mix the lighting in photoshop with masks afterwards.

Like in car photography they often take multiple shots of the car throughout the day to get different lighting, and then they can mix it together in photoshop afterwards. Maybe they like the lighting on the front in one of the pictures, but another picture has better lighting in the back, so they will add that light with masks.

My workaround has been to render 4 times, each with a rotated dome light. But it would be nice if I could do it in one render, instead of having to render 4 times.

2018-11-11, 20:43:51
Reply #9

oddvisionary

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Like in car photography they often take multiple shots of the car throughout the day to get different lighting

I'm specializing in photo realistic automotive rendering, and obviously have a huge interest for car photography (I have a photographer background) and I've never saw that in my life. They do it yes but with flash/spot light etc but never like you said. If they do, well, it must be one guy out of the millions of photographers out here.

Also never saw anyone mixing different HDRIs, we all switch between them, not use them like you do which is very uncommon and I don't see the point to be honest. I do like to see a convincing results with your technique because so far, I'm not sold. No offense of course, just my personnal opinion.
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2018-11-13, 15:25:53
Reply #10

Xntric

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Last thursday our school had a visit from a guy from Sunday digital, who is making BMW commercials. I showed him my work, and got some feedback. In my scene i had simply rendered a car using HDRI lighting with a matching backplate. He said that, what they typically do is add additional fake lighting to the scene, or rotating the HDRI and making multiple renders and then combine them in photoshop.

He also said, that when they make photography of cars outside, normally what they do is that they get to the location early in the morning and start shooting photos there, and then take shots throughout the day so that they have different lighting. Sometimes they also rotate the car a bit, to get lighting to hit other sides of the car, or maybe get a nice light gradient on the side etc. so they can mix that in photoshop.
They also some fake lighting like you said with flash- and spotlights.

I'm no expert, but it has seemed to work for me.

I've attached a photo that shows before and after of using 4 renders each with the same HDRI just different rotations. I think it has improved the lighting.

2018-11-13, 16:47:39
Reply #11

oddvisionary

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Last thursday our school had a visit from a guy from Sunday digital, who is making BMW commercials. I showed him my work, and got some feedback. In my scene i had simply rendered a car using HDRI lighting with a matching backplate. He said that, what they typically do is add additional fake lighting to the scene

Yep, exactly what I said, so far so good.

or rotating the HDRI and making multiple renders and then combine them in photoshop. (...) they get to the location early in the morning and start shooting photos there, and then take shots throughout the day so that they have different lighting

They must be taking different shots yes but never saw someone mixing morning sun light with after noon and sunset night light. It will look like crap to be honest. It's not even natural, not at all and I never saw that yet on any commercials.

-

If you want to improve your lighting and make it look professional : Get some Professional/High quality HDRI+Matched Backplates, add additional lights (area lights enough for you to start with, and it's what most pros uses).

If you are looking at automotive resources I made a place for that. You have a category on the left called RESOURCES : https://discord.gg/DEUuNs7
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2018-11-13, 17:41:13
Reply #12

sprayer

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Quote
If you want to improve your lighting and make it look professional : Get some Professional/High quality HDRI+Matched Backplates, add additional lights (area lights enough for you to start with, and it's what most pros uses).
this all in tutorials at youtube corona channel, Ludvik perfectly explains
list=PLt4UrWcQaAX-k40KpVTt-EMorC_mOfieR

2018-11-13, 18:35:20
Reply #13

Juraj Talcik

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There are few options how to mix HDRi in single scene, although none currently for LightMix.

1) Using CoronaMix in linear mode you can mix two HDRi in any way you want, multiply/lighten/etc...  You can individually rotate each, set their color/contrast/,etc..
2) Using Composite you can not only mix multiple HDRis (as many as you want) but also mask them. You can keep Layer1 as diffuse skylight and Layer2 as sunlight and voila ! You have "Sun&Sky" system with HDRi !

Example on how you would use this for visualization of cars would be as follow: Use layer1 as base environment HDRi (cityscape, forest, road,etc..). Use Layer2 on top with Add mode of studio setup created for example in HDRI STUDIO. This way you can keep independent control of your natural light and additional studio lights.

As personal opinion, mixing different times of day of natural light looks very strange. I've never seen this in workflow of any car retoucher. They do blend and mix a lot lights but always at least in slightly natural way.
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2018-11-13, 20:41:19
Reply #14

Xntric

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Quote
They must be taking different shots yes but never saw someone mixing morning sun light with after noon and sunset night light. It will look like crap to be honest. It's not even natural, not at all and I never saw that yet on any commercials.

I'm pretty sure that's what he said, maybe the tint the light, so it won't have morning sun colours, or I don't know.

Quote
If you want to improve your lighting and make it look professional : Get some Professional/High quality HDRI+Matched Backplates, add additional lights (area lights enough for you to start with, and it's what most pros uses).

Thanks, I'll try to do that for the future. Unfortunately, good HDRI's are expensive for a student like me. I'd love to get some feedback from you on the lighting in the picture I have attached to this if you don't mind.

Quote
If you are looking at automotive resources I made a place for that. You have a category on the left called RESOURCES : https://discord.gg/DEUuNs7

I'll definitely be checking that out, thanks.