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Cloned meshlights ~150+ trying to get render times down from 35min/frame

Message 1 of 10
440 Views, 9 Replies

Cloned meshlights ~150+ trying to get render times down from 35min/frame

Hi Folks, I've been working on ways to get reasonable render times for a test project with Arnold. I'm a relative noob and been teaching myself C4d/Arnold for a while now.

I'm Cloning a lightbulb to a spline that contains a filament with a meshlight applied. I then have the lights turn on/off using a mograph effector via a user_data_rgba shader applied to a basic material which is applied to the Meshlight.

The lightbulb glass material is using a reduced transmission weight to allow the glass to 'glow' or hold some of the light - although this is making it a bit milky - still better than nothing. I've reduced the mesh light parameters as much as I can while still maintaining a lightbulb effect and to try to keep the noise to a minimum.

Still getting noise on the meshlight but getting better and also getting the odd firefly.

I'm rendering 1920*1080 on a MacPro 2019 16core and have the worst frames down to about 35min a frame.

I'm using Arnold Sky for specular only, rest of lighting is via 3 Quad lights.

If anyone could help me learn how to achieve this I would be forever grateful!





Labels (3)
Message 2 of 10
in reply to: Jo_Griffin

Mesh lights are expensive to render. Could point lights with/without emission work instead?

Lee Griggs
Arnold rendering specialist
Message 3 of 10
in reply to: lee_griggs

Thanks for the response! I'll give them a shot.

Message 4 of 10
in reply to: Jo_Griffin

ok, let us know how you get on!

Remember you also have the light_decay filter so that you control the light falloff.

If you do use emission, remember to increase diffuse samples (will add to render times though).

Lee Griggs
Arnold rendering specialist
Message 5 of 10
in reply to: lee_griggs

OK will do. Have rendering times halved so far with the point light which is good. Now I just need to work out how to get the Mograph shader to affect the point light. More rabbit holes 🙂

Message 6 of 10
in reply to: Jo_Griffin

Spent the day trying to work out how to apply a mograph effector to the cloned point light and not getting very far 🙂 Mesh light had ability to take a shader as the colour which you can then use user_data_rgb for the effector but struggling to find a way to pipe something into the point light.

Message 7 of 10
in reply to: Jo_Griffin

Yeah my scene is getting really laggy with all the mesh lights. I'm going to try it with the point lights. Also, let us know if you found a way to use the effector on the lights.

Message 8 of 10
in reply to: Anonymous

It's wrecking my head! 🙂 Not sure there is a way. I did try to use light_decay filter and apply user_data_rgb to the shader but it won't connect.

Message 9 of 10
in reply to: Jo_Griffin

I worked on something similar. Here is what I found to work faster.

Since it seems you need to keep the Mograph shader then. . .

For the mesh light don't use complicated Geo. Simpler is faster and less fireflies. You can use the coil to render when they are off though.

I rendered this at 1400 x 1000 and took about 10 minutes with skydome but no area lights. So it is close to the same as yours but you can cut it down by half if you split up the bulbs.

Turn on Matte for all your non transmissive materials.

This took about 3 minutes.


Now do the opposite but turn off everything but visible to camera rays on the bulbs.

It is the equivalent of rendering just the filament without the bulbs - you just want them on for the matte. Now you can render your background without cranking up your transmission/tranparency ray depth and samples.

This took about 2 minutes.matte3.jpg

If you need more light on your background then add a shader to the bulbs with just emission and turn on everything but visible to shadow rays.


And one last thing. I don't know how it would work in C4D but I have all my fillaments connected as one piece of Geo with an intensity variable per piece and then I add that Geo into one mesh light instead of of many individual lights. The above would work either way.

Hope this helps.

Message 10 of 10
in reply to: brian_Foley

Hi Brian, thanks so much for taking the time to answer! Some very interesting concepts there that I'll need to get my head around. Will report back. I had already simplified the filament mesh it didn't help much but I'll keep digging. Thanks again!

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