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Infrared Foliage effect

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Hi
I have an idea for a portfolio piece I want to create rendering tree  foliage as if shot using infra red film.
This is sort of the look I am after
https://www.pinterest.ca/pin/107453141084546172/

Any shader experts able to suggest tips on how I would go about building the leaf shader?

I'm using Redshift but the same principles should apply regardless of rendering engine.

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Hey, nice images, I used to shoot some pictures like that more than 15 years ago, with infrared film !

But considering that nowadays film is rare and that modifying your DSLR to remove the IR filter is complicated / expensive (and you lose your guaranty), I am pretty sure that Photoshop was used in most of those images (mayeb with the help of some « IR » filters on the DSLR + auto tone function of Photoshop).

So my advice would be to generate a 3D LUT with DaVinci or other software, and either import that LUT into Houdini, or shade your scene « naturally », and then grade it into DaVInci, Nuke etc... (you’ll have to tweak more than the foliage, who appears white as vegetals emit lots of IR, but also trunks and other « colder » objects).

There are plenty tutorials on Google to generate LUT that fake infrared pictures.

Hope that helps

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3 hours ago, StepbyStepVFX said:

But considering that nowadays film is rare and that modifying your DSLR to remove the IR filter is complicated / expensive (and you lose your guaranty)

I bought a camera already modified for less than what a new one would cost, that was 10 years ago though but I don't think its too bad. People buy smartphones for $1000 nowadays, thats more crazy i think.

Ontopic though, why not just make a standard leafshader but instead of green for color you use white. It is white because it reflects all (infrared) light.

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Posted (edited)
2 hours ago, Skybar said:

I bought a camera already modified for less than what a new one would cost, that was 10 years ago though but I don't think its too bad. People buy smartphones for $1000 nowadays, thats more crazy i think.

Ontopic though, why not just make a standard leafshader but instead of green for color you use white. It is white because it reflects all (infrared) light.

Well, I can’t tell, I never bought a smartphone :-) (but I use the one my company gave me).

I admit I never looked at the price of such modified DSLR, just read some articles in photography magazines I buy from time to time...

One thing I remember, that can be useful if you want to achieve the real IR look, is that it was very difficult to have a good focus, IR rays converging at a different focal point, and that apart from that, there was kind of a glowy effect around vegetation... maybe it was just focus problem, but maybe it was different air temperatures that was radiating from around the vegetation. If I can find my old negatives, i will try to scan that and publish it to you guys. Maybe you had a different experience with a modified DSLR Skybar ?

But if matching this IR film look is not the main purpose, indeed, just changing the colors of the shaders and playing with gamma on the final image may works well without too much complications.

see U guys and Artemis don’t hesitate to share your results ! I am curious to see what you get !

Edited by StepbyStepVFX

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1 hour ago, StepbyStepVFX said:

One thing I remember, that can be useful if you want to achieve the real IR look, is that it was very difficult to have a good focus, IR rays converging at a different focal point, and that apart from that, there was kind of a glowy effect around vegetation... maybe it was just focus problem, but maybe it was different air temperatures that was radiating from around the vegetation. If I can find my old negatives, i will try to scan that and publish it to you guys. Maybe you had a different experience with a modified DSLR Skybar ?

I'm not a photographer expert by any means, but I didn't notice anything like that at all. It worked just as a normal DSLR, except the fact that the colors of your image is different :)

Another thing you could try, create your scene normally with green leaves etc. Then render with only red lights and in comp pick the color of where the leaves are and set the white point to that. That's essentially mimicking what happens in real world and what you do in camera. To set the white balance on my camera I photographed straight down into grass on a sunny day, so green stuff becomes that nice white. If you don't do this the image is mostly red.

I think the easiest thing is to just fake it though and do white leaves from the start.

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1 hour ago, Skybar said:

I'm not a photographer expert by any means, but I didn't notice anything like that at all. It worked just as a normal DSLR, except the fact that the colors of your image is different :)

Me neither, I was just a hobbyist :-)

By the way, Wikipedia was not existing by that time, and I understood just today, thanks to you, why there was this "glowy vegetation" : The prominent blooming or "glow" often seen in the highlights of infrared photographs is an artifact of HIE [the name of the B&W Kodak film I used] and not of infrared light itself (nor even of all IR-sensitive films). This is because although conventional photographic films have an anti-halation layer that absorbs scattered light, HIE lacks this backing.

I will sleep less ignorant tonight... :-)

I am wondering, now, if I had the same glow with the IR Ektachrome. But anyway, seems the DSLR performs better that those films, so they are the new reference I guess, if someone wants to fake it.

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Posted (edited)

Make the leaves white with lots of diffuse and translucency. I've shot a lot of digital infrared over the years (modified a few cameras to do so). If you want some raw photos to mess with I posted a bunch online (download the ZIP files).

Changing the channels in Photoshop kind of works but not really. The values will look similar but the leaves will be too reflective and other things won't be right (glass looks black, the sky looks black, other stuff looks different besides just the leaves, especially people and clothes).

Edited by lukeiamyourfather
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