tube lights

tiktane358 · Post by **tiktane358** » Wed Dec 27, 2006 6:34 pm

Hello
I made a test with an old file I do a long time ago. I just wanted to see if I can render tubes lights that are on the ceiling.
Anybody have a great tip ?

Post by **jure** » Wed Dec 27, 2006 6:47 pm

Hmm yes on quality tab switch to Direct mode and if you get grainy lights turn up lumi light max value.

Post by **silverlw** » Wed Dec 27, 2006 6:50 pm

I would use a different approach and use inderict/photonmapping but hard to tell since we dont have the specific scene to test with. Do a quick test and see how what's faster. Direct mode is very accurate but can take long time comparable to Fprime/montecarlo.

Post by **jure** » Wed Dec 27, 2006 6:54 pm

Nah don't listen to silver.

I use direct mode alot and sometimes it's even faster than indirect.
Anyways in scenes with lots of small lights you're better off with direct. Also you might want to switch to photon map since it seems to work better in scenes with lamps.

Mario · Post by **Mario** » Wed Dec 27, 2006 10:18 pm

ies. light would do the work here.

Post by **jure** » Wed Dec 27, 2006 11:01 pm

Well IES lights themselves wouldn't help the render look better. IES is just a standardized format for describing light intensity of a light fixture.

Mario · Post by **Mario** » Thu Dec 28, 2006 12:47 am

Agree, but this king of tube lamps have a specific distribution that you could only imitate with ies. files.

Post by **jure** » Thu Dec 28, 2006 11:36 am

Mario wrote:Agree, but this king of tube lamps have a specific distribution that you could only imitate with ies. files.

I think lighting&surfacing skills of an artist are far more important than IES files....

Mario · Post by **Mario** » Thu Dec 28, 2006 1:26 pm

Depends if your looking for accurate lightning distribution or not.

tiktane358 · Post by **tiktane358** » Thu Dec 28, 2006 1:43 pm

What would you use Jure for tubes lights : 3d tubes with % of luminosity, or linear lights ? For linear light what is the better : 100000% with 1cm faloff or 50% with 3m ?
What are the linear light threshold ?

Post by **jure** » Thu Dec 28, 2006 2:20 pm

tiktane358 wrote:What would you use Jure for tubes lights : 3d tubes with % of luminosity, or linear lights ?

Hmm.. well geometry lights give you more freedom in shaping and are easier to place. They may render slower if they are not simple 4 point polys. You control quality (noise) of this lights with "lumi lights threshold - min - max".
On the other hand linear lights might be a bit faster to render, but you'll have more work placing them...

tiktane358 wrote:For linear light what is the better : 100000% with 1cm faloff or 50% with 3m ?

I think it shouldn't make any difference...

tiktane358 wrote:What are the linear light threshold ?

Threshold is a difference between neighbouring pixels at wich Kray will use more rays. Kray will use at least min rays at each pixels and will shoot more if difference between pixels exceeds "thershold" value. But even if difference between pixels is still more than "threshold" it won't use more than "max" ray.
This method is called importance sampling and you can find it throught Kray and it always works the same way.

tiktane358 · Post by **tiktane358** » Thu Dec 28, 2006 5:22 pm

I tried playing with these values and I found something that works when the tube light is far of the closest surface about 1 meter.
When the tube light is 5cm close to the wall for example I have a lot of grain and I think that the light burn a lot at source and don't "light" enough around.
Can you show us an example of "Jure" neon in a black room ?

Post by **silverlw** » Thu Dec 28, 2006 5:37 pm

tiktane358 wrote:What would you use Jure for tubes lights : 3d tubes with % of luminosity, or linear lights ? For linear light what is the better : 100000% with 1cm faloff or 50% with 3m ?
What are the linear light threshold ?

It doesnt matter. Lights with inverse square falloff is just light with a natural and physicaly correct falloff. If When you change it's falloff radius OR change it's luminous power, the outcome will be exactly the same thing. Stronger or weaker, only that.

Post by **jure** » Thu Dec 28, 2006 10:24 pm

tiktane358 wrote:I tried playing with these values and I found something that works when the tube light is far of the closest surface about 1 meter.
When the tube light is 5cm close to the wall for example I have a lot of grain and I think that the light burn a lot at source and don't "light" enough around.
Can you show us an example of "Jure" neon in a black room ?

I've played with it some and it seems that you're better off with area or linear lights than with lumi polys. Lumi polys seem to produce too much noise...

Post by **silverlw** » Sat Dec 30, 2006 2:02 am

Im bound to agree with jure after some tests. This example is photonmapping + caysics and "auto" mode. Auto mean everything stronger than 100% luminosity will be rendered in direct mode ,the rest in indirect mode. Custom lights is possible with just polygons but if we use only polygons like i did in this example we start to enter into Maxwell domain rendertimes

and i also did one with arealights only.

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tube lights

tube lights