[rendek]

Hi guys, This is an old lamp design of mine. I tried to render it for the first time in maxwell. Please let me know how you think I could improve it and if you can make sense of it...

[sampson]

nice & interesting design, ...i think you need to let it render a little longer so we can see the materials better.

[rendek]

thanks sampson, will do that...

[rendek]

I rendered the lamp for 33 hours 20 minutes which got me to S.L. 19.10 (3.73 GHz duo-core, dual Xeon). It is still quite grainy. I simplified the emitter geometry which made a big difference. I modeled the bulbs all the way to the filaments which are actually the emitters. The top parts of the bulbs are silver coated (A lamp). The corners of the cube are "carved out" by 8th spheres which are acting as reflective shields. The "x" shapes in the middle are frosted glass panels.

here is the maxwell package:

http://homepage.mac.com/adamrendek/1110go.zip

I'm curious to hear from you how I could improve this scene. Thanks in advance for your comments!



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[superbad]

The biggest problem is that you're trying to use very small emitters to illuminate a large area. The way this thing works (this might not be 100% technically correct, but it's the right general principle) is that rays get shot out from the camera, bounced around, and the ones that hit a light source get counted. And you have to get multiple rays at each pixel location to clear the noise. (Anyone feel free to correct that if it's terribly wrong.) So it's extremely unlikely that any particular ray is going to hit your little emitter wire, especially when it also has to get refracted through a couple layers of glass. Thus, many, many rays need to be sent, which means very long render times.

I would try making the inner surface of the bulb reflector an emitter, which would increase your emitter area by a large factor. Also, I'm seeing some tesselation in there, so you should check your smoothing settings.

Cool design, by the way. Is that in production at all?

[rendek]

thanks superbad! your comments were really useful!! I'll try to modify the geometry and adjust the smoothing... it's not in production yet, hopefully it will be soon...thanks for the compliment.

[Tim Ellis]

There are a couple of ways to help reduce noise levels.

In addition to your existing emitters, a reasonably large emitter plane, positioned behind the camera, with a single face and a low wattage, should help to reduce the level of noise.

You should be able to get this new emitter to give out just enough light to help clear the image, without it detracting from the main light.

You could also try the trick of removing a side of the room that's out of shot, to let some of the light rays escape to reduce the amount of light bounces needed in the calculation.

Very interesting design.

Tim.

[rendek]

thanks Tim, I really appreciate it... I actually have a curved backdrop as the background, so there are only the top and the back partially covered. (the corner of them is curved). That emitter behind the camera sounds like a really interesting trick. I'll give that a try.

thanks for the comment.

[Tim Ellis]

In which case a soft skylight or hdri/mxi in addition would help. (I was thinking the lamp was in a contained room/box. )

Other tip would be to turn on multilight and specify an mxi path before rendering. That way you can control the hdri, the large emitter plane and the lamp emitters when you stop the render. Much easier to tweak a multilight than to constantly re-render.


Tim.

[rendek]

Thanks, Tim!! These are great suggestions! I'll try them.

[rendek]

Hi Guys, I remodeled the lamp with MoI and re-rendered it. (Tim generously checked the model and pointed out some geometry intersections). Also, I added an LDR to help clearing the noise.

original image:

resolution: 1600x1200
time: 58h19m47s
s.l.: 20.69
benchmark: 80.49

Comments would be highly appreciated.

thanks.

[sampson]

...very nice indeed.

[x_site]

very nice... but how many people does it take t change the light bulbs?

[Boris Ulzibat]

very nice... but how many people does it take t change the light bulbs?

At least 5, i guess. One of them is standing on a chair, holding a bulb with both hands, the rest are spinning the chair!

[thxraph]

i love it!! but 58H for an SL20 + this good benchmark, what a crasy thing...

btw, great design!

Raph