Author Topic: Light, reflections and GI  (Read 4627 times)

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Offline vouart

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Light, reflections and GI
« on: August 09, 2016, 12:54:09 am »
Hi there!

First, I'am new in this forum and like to say hello.

Second: sinca a long time I work with cinema 4D and Vray. For a customer we need to generate the pictures with Keyshot. (Native exchange with CAD)
Our proble is delicate, I think. It's about light and global illumination.

In picture "Light_02" that's what we want generate. Picture "Light_01" is the first try.
General question: is this possible? to work with lights like a physical renderer?
In the manual there are is just a littl nothing about lightning in the scene.

Thank you a lot for your inputs,

Best regards.

vouart


Online DriesV

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Re: Light, reflections and GI
« Reply #1 on: August 09, 2016, 05:39:49 am »
Hi Vouart,

First of all, welcome to the forum. :)

What you are trying to achieve is definitely possible in KeyShot.
There are multiple ways of doing this. I will highlight one of them here.

Attached is a sample rendering. I tried to make a simple representation of your scenario.
A sample scene can be downloaded here.

Model preparation
A good solution would be to put a plane surface (part Light_1 in the scene) behind the translucent cover as a light source. If you assign a light material to it, you can control the direction (front and/or back) of the light.
In this case it might be useful to create an offset surface of the outer surface of the cover (part Cover offset_1 in the scene). If you then assign an 'Area Light Diffuse' material to it (disable 'Visible in Camera' and 'Visible in Shadows'), you can more easily control the amount of light that should fall onto the wall.

Materials
The 'Translucent' material is going to be great for the light cover. It support subsurface scattering. So a light that is put behind it will bleed through for a soft look.
The 'Area Light Diffuse' material is the best option for any light object that is to act as a main light source. This light material support physically accurate units (radiant Watt, Lumen and Lux(Lumen/m²)) and physically plausible falloff.

Lighting
It is probably a good idea to enable 'Interior Mode'. Especially if the light fixture is eventually going to be placed inside an actual interior model. Interior Mode is great whenever you have a 'difficult' lighting scenario (read: mainly indirect illumination).

I hope that helps to get you started.

Dries
« Last Edit: August 09, 2016, 08:12:59 am by DriesV »

Offline vouart

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Re: Light, reflections and GI
« Reply #2 on: August 09, 2016, 07:07:43 am »
Dear Dreas


Thank you for you quick answer.
Two things: I can't open the file after download. Whats wrong on my side?
And how long do you need to render this picture?

Best regards.


Online DriesV

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Re: Light, reflections and GI
« Reply #3 on: August 09, 2016, 07:12:18 am »
Are you running KeyShot 6? You will need KeyShot 6 to open this scene.

This image (2000 x 1500) rendered for about 12 minutes on my 32 core machine.

Dries

Offline vouart

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Re: Light, reflections and GI
« Reply #4 on: August 09, 2016, 07:48:25 am »
Got Keyshot 6.2.105 latest version i think...

Online DriesV

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Re: Light, reflections and GI
« Reply #5 on: August 09, 2016, 08:03:11 am »
My bad.
Here is a ksp that works.

Dries
« Last Edit: August 09, 2016, 08:11:59 am by DriesV »

Offline DMerz III

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Re: Light, reflections and GI
« Reply #6 on: August 31, 2016, 11:23:54 am »
Well done Dries, the offset geometry definitely makes sense here. Thank you for breaking that down.

The results look great, and as always, the texturing is spot on.