How can I make accurate LED lights in Maya/VRay?

#1

Hello, I’m trying to figure out by what means to properly simulate a 5mm LED bulb.

here’s my model so far

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So far I’ve just kind of faked it by using colored sphere lights:
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but I’m trying to go for a realistic PBR setup where I don’t have to use shortcuts to get a realistic LED light source/material combination

These are my references:

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With renders, this is as close as I’ve been able to get:
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The problem is I’m using a sphere light and LEDs’ light source is a tiny disc resting at the top of the cathode. The light shines up and is refracted around the colored LED shell, but there is always a pretty hot center at the light’s source point.

The problem with VRay lights that I’ve run into so far are that light meshes don’t have enough intensity:
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But as in the renders I have above, the sphere light source itself is wholly the wrong shape.

I don’t know if I’m just using a wrong material, or if there’s some secret to VRay’s lights that I’ve yet to learn, but I would die for some solid help on solving this issue…

Thank you!!

#2

You can use either vray light mesh option, or use vraylight material. In any case, if you want to use the tiny object as a lightsource, it will take a long time to calculate to shoot enough samples. And you will have to increase its brightness a lot.
But any way, in real life you would not see the inside of the lamp and the surroundings as well due to exposure. The lightsource would be too bright to distinguish any details inside of it.
You can create the glower, and also create an invisible lightsource nearby, which isn’t a realistic setup, but it would render faster.

#3

I’m not trying to illuminate the outside of the lens so much as the environment itself with a lightsource that comes out of the lens.

Your argument that one wouldn’t be able to see the inside from exposure isn’t true, necessarily, and as with anything in 3D I’m working with simulated cameras, so I’d be able to adjust exposure, anyway.

I’ve tried both light mesh and light material, but I’m running into the same problems… :\

I’ve gotten some pretty good results from certain angles, but my main dissatisfaction comes from the fact that unless the light source itself breaches the edge of the reflective bowl, it just casts a huge shadow beneath the LED, and either way, there’s no real focus on the light beam at the tip of the lens, like you’d see irl:

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(this is photo reference)

these are my most recent renders:

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#4

If you want the light to focus like a laser, use vraylight directional function. 1 = all rays go into one parallel direction, 0 = rays go in all directions. uniformly.
In the first image you’ve initially shown, the lights were placed in some kind of an appliance/vehicle. So they were much closer to the surface, and for them to light something around, they’d have to be very bright. In the last photo example the light is far away from the sorface. But if they don’t serve as the main lightsource, you might be right, that they might be vsible.

#5

Yeah, tail lights are about 400 lumens, though I have these cranked up to like 2500 each. I swear there must be something wrong with my material that it’s just not bending the light around proper. These more isolated renders are more about just getting the right behavior since if I can do it on its own, for sure I’ll be able to get the results I want in any environment

#6

Maybe check out how modern LED chips are really shaped. The LEDs you show here are old style 3/5mm LEDs that are effectively not used in modern devices. Many of the LEDs used for illumination have multiple emitters under one lens and depending on use they have focusing reflectors inbuild. The Lens is also often a lot smaller and flatter than the 3/5mm LED epoxy body you show here.
Your approach with the 3/5mm LEDs would be a match to show the illumination of PSU status LEDs etc. but you only see them illuminating anything in low light conditions. If you want to use this to really light a scene you will be hard pressed for realistic results, because these kinds of LEDs are not used for illumination.

#7

High power 5mm LEDs can deliver up to 1.x Lumen. There is a reason why they aren’t used in tail lights, the 5mm formfactor does not allow for the neccesary cooling.
Your light distribution problems might come from the fact that the emitter is encased in the epoxy and since it is very clear epoxy you do not see the light within the epxoy, but only when it leaves the body of the LED and is either directly shining into the camera or illuminating surfaces. In best/worst case you can see the light when it hits particles or faults in the epoxy. Add to this that a lot more effort is made to polish the lens part of the body than the cylindrical or bottom and you have a recipe for very complex emission patterns.