Lighting trick : smooth objects with few emitting faces.

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Lighting trick : smooth objects with few emitting faces.

Postby ROUBAL » Fri Sep 17, 2010 12:19 am

ROUBAL Fri Sep 17, 2010 12:19 am
Hi, what I want to share is not a tool, but a simple method to create high poly luminous objects (lamps, bulbs, lanterns...) using very few emitting faces, to reduce your render time.

In the image below, the two lanterns contain only 46 emitting faces, and the bulbs themselves are not emitting light.

The trick is simple : The bulbs can be low poly or high poly with subsurf. This has no importance !

Currently, for what i have seen and if I am not wrong, light can't pass through glass materials, but I have noticed a very useful thing : Diffuse materials with opacity set to zero still emit light ! This allows to get transparent and even totally unvisible objects to emit light !

In the example below, there are two kinds of emitters : inside each bulbs there is a small cube with diffuse emitting material. This light doesn't propagate beyond the bulb enveloppe, but the bulb itself is luminous.

- The bulbs are made of a specular material with high IOR.
- The external glass of the lanterns is made of diffuse emitting material with an opacity of 0.005 and a power of 5.

I kept a low value of opacity but without setting it to zero, in order to make the glass surface slightly visible. The power emitting value of the glass is 5 in the image below.

On the second image the emitting glass of the lantern has a power of 20.

I hope that you will find this little trick useful !

Best regards,

Philippe.
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PoliceStation-OctanePre23_v4_09.jpg
PoliceStation-OctanePre23_v4_10.jpg
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Re: Lighting trick : smooth objects with few emitting faces.

Postby 3rdeye » Fri Sep 17, 2010 7:37 am

3rdeye Fri Sep 17, 2010 7:37 am
thx alot mate...was really stuck with this one...your renders look neat...and I need to give it a try now..

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Re: Lighting trick : smooth objects with few emitting faces.

Postby SurfingAlien » Fri Sep 17, 2010 7:47 am

SurfingAlien Fri Sep 17, 2010 7:47 am
Hey Philippe,
thanks for sharing this neat trick!
I'm not sure how "unbiased" is this approach but it works as a charm in your shots!

cheers,
Alessandro
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Re: Lighting trick : smooth objects with few emitting faces.

Postby ROUBAL » Sat Sep 18, 2010 1:49 pm

ROUBAL Sat Sep 18, 2010 1:49 pm
Thanks ! :)
French Blender user - CPU : intel Quad QX9650 at 3GHz - 8GB of RAM - Windows 7 Pro 64 bits. Display GPU : GeForce GTX 480 (2 Samsung 2443BW-1920x1600 monitors). External GPUs : two EVGA GTX 580 3GB in a Cubix GPU-Xpander Pro 2. NVidia Driver : 368.22.
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