CloudyPlastic/Translucent with LED's (again)

[mattjgerard]

Not sure what is going on, I continue to have this problem. LED's shining through various diffuse, cloudy or translucent plastics. I got permission to package up this project, to get some hep with it. It is an unreleased product, but will be out soon.

There are 4 leds in a square config inside the unit, that shine upwards through the plastic extrusion. What I'm having trouble doing is balancing and adjusting all the settings to get the rich red saturated color I see on the unit itself. I need to find one material that looks correct unlit, and with red, green or blue LED's in it. Seems that all the colors are washed out, and adjusting the brightness only blows out the color, or in some cases actually changes it.

I've tried going through each material with the same LED settings and adjusting each slider, dropdown and setting I can find, trying to document what that setting actually does to the image, and how it interacts and reacts to other settings. I just can't make heads or tails of it and it seems more complicated than it needs to be to get the result I'm looking for.

In the past Dries helped me with a touch button that was green, and ended up having to do it in photoshop with "tone-mapping" whatever that is, but that techique isn't working with this setup. BDesign also helped me out as well, but I can no longer get that technique to work either. Please see the pics of the real thing, and I am willing to pay for someone that can help me figure this out. I've seen the training that is out there, and bought a lot of it from Esben and Magnus, but none of them really go through and explain in simple terms how to get a look like this. We have a lot of products (and more coming) that I'll need to use this on.

The other problem is that when I render as is, with the reds more of a pink and thinking "Eh, I'll just color correct it in photoshop" the extreme amount of correction needed just blows out the noise and artifacts. I have been using the Nik Denoiser in PS, but it still doesn't work great, and the denoiser in Keyshot is like blasting a cracker with a shotgun. Removes too much detail.

Main Problem is getting a deep rich color through the plastics. Any help or advice is greatly appreciated. Between the color, noise, lack of smoothness in the materials I'm getting pretty frustrated with not being able to figure this out!

EDIT: The Red image below shows the actual falloff of the light, but the color is way to thin and washed out. the blue and green show the saturation of the color, but the falloff is way off due to the exposure I had to adjust to get the color to show properly. So, blue and green correct colors, wrong falloff, red, wrong color but correct "look"

[andy.engelkemier]

This is probably one of the most difficult materials, because so many things effect it. What's the actual cloudiness number? Yeah, we're all guessing buddy. Transparency thickness? Well, you can name pretty much every setting, and they all effect eachother, and it's probably just a guess. And if you didn't have a perfectly physically correct lighting setup? Well, the whole thing was wrong then, so only worked in that specific instance.

I keep thinking the best starting point is to try and use nearly perfect data with specifically known values and try and match them. But you'll likely be sorely disappointed to find out that it's just not going to work.
You'll find a physical emissive object is more accurate in appearance, but with less control and a HUGE hit in time. (in keyshot at least), and with spotlight, the only thing that actually seems to be somewhat accurate is the beam angle and radius.

So one idea, before going further is to just figure out what you want it to look like, and basically paint it in photoshop. I do LED's in phtoshop about 95% of the time, even behind cloudly objects (for stills only of course). And I usually just do it all with layer effects. Some tricks there are, glow sucks. Drop shadows don't have to be multiply. Use add instead of screen for almost Every layer. Add some internal shadow or glow to make it look like the light itself isn't 100% evenly lit. You get the idea. It'll still be taste. Some people will be like...Why is that pink instead of purple? Where others will say, wow, that purple light is Spot on. Yeah, if you're looking directly at an LED, not behind cloudy plastic, the light itself is usually just plain ol' white.
So you could always do that, then just import that as a texture...or just leave it there. Depends on what you're after.

BUT, if you're after what you're seeing. You have a constant light output. That was the first thing I turned off. I increased the radius to my guess at what the size of LED was, and Just a little more. If it's just a tiny surface mounted LED, you're probably right with 1mm, but it's also square. I mean, we're going for accurate looking, not physically accurate right? Anyway, Really bright point lights do not make global illumination happy in Any software. So make the radius as big as you can get away with. And the light should falloff, as far as I know. This is likely to be a discussion. And I'm not always sure what the engineers were going for when they named something. Light falls off quadratically. I mean, that's just a fact, right? My guess then is that falloff of 1 is the normal inverse square falloff? The tooltip there seems like an engineer thought Non-engineers needed an explaination, but it still sounds like an engineer is explaining it in engineering terms? It seems like zero is no falloff, 1 is physically correct.

So lumens, this is where things get tricky. Lumens isn't really a value that should be used here, because it's a value we are familiar with, but it's not power...it's value to be measured After? (lots of people cheat how they measure that too, which is why a 300 lumen flashlight doesn't seem as bright as the other 150 lumen flashlight you might have). Anyway, it's more of a measurement that comes From the source, not how much light is actually at the source. So this doesn't take surface area into consideration. And the only other measurement keyshot gives us is Watt? Ok, so here's where you get stuck when trying to make something physically correct. I thought they gave us more, but I use several things at once, so sometimes mix them up. Lumen it is. I had to bump it up to 10,000 to get what I was after though. Where the actual LED there will probably measure something like 30-40 lol. (but at what distance? again...not a good measurement for a light Source, but it's what people think they are familiar with)

So changing those things actually works pretty good with your existing translucent material with no changes. Maybe dial back slightly on the brightness, or bring the size closer to 2mm. But that renders pretty darn slow. And roughness is likely not high enough. You can clearly make out the disk inside. Although, only the part that is intersecting, which it shouldn't.

For your cloudly plastic, refraction was too high. Cloudiness should be pretty darn high, maybe in the .6-.9 range. And scattering direction, probably between -.5 and -.3. That'll scatter most of the environment light back toward the camera, making it look more white. It's really difficult to get white cloudly to look white without that, unless you make it Pretty transparent.
If you're after speed, and using lights, you can likely turn off GI. It really isn't contributing if you're using cloudy plastic. And Definitely turn off ground illumination here.

Lastly, do this kind of test in a good physical environment first. NOT a studio environment. Those lights don't look very accurate at all. The downside to lots of the physical ones are the lighting is quite even, or will add a bunch of unwanted color. But you can always desaturate them.

Good luck. Hopefully someone else that jumps in and corrects me on a few things (welcome help for me as well) can shed some light on other items that will help.