Strange light emission

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Jambert
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Strange light emission

Post by Jambert » Mon Dec 07, 2009 8:49 pm

I use neon light. I modeled neon with perfect circle extruded. I don't understand some shadows!?

Help needed, thx :)

Sorry for blured picture but it's a private job.
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fused
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Re: Strange light emission

Post by fused » Mon Dec 07, 2009 8:56 pm

thats weird.... can you show a wireframe of your lightsource?

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Jambert
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Re: Strange light emission

Post by Jambert » Mon Dec 07, 2009 9:12 pm

Some tests :?
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OnoSendai
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Re: Strange light emission

Post by OnoSendai » Mon Dec 07, 2009 9:19 pm

Maybe it's the light blocking other parts of the light :)

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Jambert
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Re: Strange light emission

Post by Jambert » Mon Dec 07, 2009 9:50 pm

OnoSendai wrote:Maybe it's the light blocking other parts of the light :)
That's it!!! thx

The affect looks a bit strong. It's the same mesh, but light emited from part 1 seems to be higher than part two :roll:
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part 1 and 2
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Blocked light
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Last edited by Jambert on Mon Dec 07, 2009 11:48 pm, edited 1 time in total.

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Jambert
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Re: Strange light emission

Post by Jambert » Mon Dec 07, 2009 10:01 pm

A shot with mesh divided
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Jambert
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Re: Strange light emission

Post by Jambert » Mon Dec 07, 2009 10:46 pm

So, my first neon model was wrong, so I tried to model it in a more realistic way.

Second Model: The shadows still looks a bit strong because model is still wrong, it needs a blended emitter. Works fine because in real life it's a gaz, but it needs very high value to compensate blend factor (here 0.9 null)

Ono, light layer for blended material is still broken, will it be fix in next release? :wink:

thx
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Glossy transparent
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Last edited by Jambert on Mon Dec 07, 2009 11:45 pm, edited 1 time in total.

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pixie
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Re: Strange light emission

Post by pixie » Mon Dec 07, 2009 10:53 pm

I think it has to do with the shape of the light itself
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Jambert
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Re: Strange light emission

Post by Jambert » Mon Dec 07, 2009 11:56 pm

pixie wrote:I think it has to do with the shape of the light itself
You and ono are right, problem come from both, shape of the light and light blocking other part of the light.

edit: any way to fix it?

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dakiru
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Re: Strange light emission

Post by dakiru » Tue Dec 08, 2009 12:16 am

Why fix it? It seems like a realistic light behaviour :)

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CTZn
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Re: Strange light emission

Post by CTZn » Tue Dec 08, 2009 12:42 am

Yes it is, Jambert. You must build deflectors around the neons ! Or, prolongate the neons into the wall or an energy supply system, that will affect the resulting emission.

A "black body" is a solid object, blocking light. Seen from the profile, the emitting surface is way smaller than seen from above (in your tests with multiple horizontal shapes).

I'm not sure about your solution wich consists of blending a null with a diffuse material... Tubes are shooting light in pretty much all directions so the diffuse transmitter is not adding much, plus the 10% null introduces strong discrepancies in the lighting solution. I'm not fan about it personally, though the way using dt only is interesting.

Multiple edits ;)
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Jambert
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Re: Strange light emission

Post by Jambert » Tue Dec 08, 2009 1:51 am

CTZn wrote:I'm not sure about your solution wich consists of blending a null with a diffuse material... Tubes are shooting light in pretty much all directions so the diffuse transmitter is not adding much, plus the 10% null introduces strong discrepancies in the lighting solution. I'm not fan about it personally, though the way using dt only is interesting.

Multiple edits ;)
Sorry my post aren't clear enough. I didn't blend diffuse transmiter, I used only one mesh, the tube, as a blend (10% emitter, 90% null). To me it's the more realistic way.

Using a mesh with a blackbody material, as pixie, give realy bad result to me (see shadows pict.2). It's physicaly correct because mesh block some lights, but in real life neon tube are glossy transparent and lights come from the gaz inside.
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blended.jpg
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blended blackbody + null.png
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FPSatan
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Re: Strange light emission

Post by FPSatan » Tue Dec 08, 2009 2:35 am


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CTZn
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Re: Strange light emission

Post by CTZn » Tue Dec 08, 2009 1:48 pm

Nice pick FPSatan !
Sorry my post aren't clear enough. I didn't blend diffuse transmiter, I used only one mesh, the tube, as a blend (10% emitter, 90% null). To me it's the more realistic way.
Oh ok. No problem, I have a tendency to misread posts myself :oops:

Well that's some hack anyways 8)

I wish true volumetric emission will be available someday !
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Jambert
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Re: Strange light emission

Post by Jambert » Wed Dec 09, 2009 9:47 pm

CTZn wrote: I wish true volumetric emission will be available someday !
An emitting smoke? Light emmision needs normal, don't think it's possible, maybe with indigo 5.0 :lol:
First step could be particule for volumetric smoke simulation :)

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