Page 1 of 1

Maxwellvolumetric to achieve light rays

Posted: Thu Dec 26, 2019 1:16 am
by Jon Sabutis
Hi,

I've been trying to achieve visible light rays coming through perforations in this lamp shade. I know this requires some sort of atmosphere or fog. I could photoshop this but I am in general interested in achieving light ray affects in the native rendering. I tried playing with the "turbidity coefficient" in the "physical sky" setting but it only seems to affect sunglight not artifial lighting like the bulb I have inside the lamp.

From some research, It sounds like my desired effect might be possible with the maxwellvolumetric extension but I'm not really getting anywhere reading the documentation nor playing with settings under FIELD TYPE: "constant" and "noise 3D". I wonder about "partical based" field type which requires some sort of importable 3D geometry. Just can't seem to find any purchasable or downloadable particle fields online in the required .bin, .abc. .rpc .prt ect file format. I have access to Blender (with limited knowledge) which I know has some particle capabilities but I can't seen to figure out how to import anything into Mstudio.

I've attached a reference image.

Thanks so much for any help!
Image

Re: Maxwellvolumetric to achieve light rays

Posted: Fri Dec 27, 2019 12:44 pm
by Forum Moderator
Hello Jon,

Yes, volumetrics is the way to go, but I would use Constant or Noise 3D. Particle-based type is intended to create effects like smoke, where the particles give the shape to the smoke.
In your case, I think the light source is too big and too close to the holes to create a well defined and visible ray.

Please, check the attached mxs file and the screenshot:

god_rays.png

Cheers!
Fernando

Re: Maxwellvolumetric to achieve light rays

Posted: Sat Dec 28, 2019 1:00 am
by Mark Bell
Thanks for the test scene. Error 18 occurred when trying to open the mxi in Multilight:

122819_error18.jpg

Re: Maxwellvolumetric to achieve light rays

Posted: Thu Jan 02, 2020 6:35 am
by Jon Sabutis
@Fernando thanks for your reply! Your scene was a helpful reference. Interesting that the wattage of the emitter needs to be artificially high (seeing yours at 200,000) for this effect to work. In general, I thought it was best practice to stick to real world values in Maxwell but it makes sense that replicating millions of dust particles would involve some faking. I was able to produce the god ray effect through the lamp perforations - but only with a planar emitter. Ray definition seems to have more to do with the shape of the emitter than the distance or size. To mimic light from a light bulb, the shape of the emitter would ideally be a sphere or cylinder but testing those shapes seems to muddy the rays. See attached images. Maybe I can fake the end product image with some stretched planes in stratetic places. Thanks again for your help! Very interesting experiment :D

Image
Image

Re: Maxwellvolumetric to achieve light rays

Posted: Sun Mar 15, 2020 5:47 pm
by choo-chee
no matter how much I try- couldn't get a simple interior get some rays of light with it. all I get is a foggy interior that renders slower than maxwell 0.5 alpha :(
any chance for a decent tut with applicable presets for it ?

Re: Maxwellvolumetric to achieve light rays

Posted: Sun Mar 15, 2020 11:24 pm
by Mark Bell
Choo-Chee wrote "no matter how much I try- couldn't get a simple interior get some rays of light with it. all I get is a foggy interior that renders slower than maxwell 0.5 alpha :(
any chance for a decent tut with applicable presets for it ?"

I second this - some setup examples would be beneficial here.