Cloudy PLastic Fun (or is it)

[mattjgerard]

Its one thing to create a material that just looks neat in a render, its a totally different animal to get one to look physically accurate. As such is my issue this fine monday morning. Attached is 2 images of a flat top illuminated touch button. Also included is a ksp of the little bugger. I am playing with and reading the manual on the cloudy plastic material that I want to love so much, but am having issues getting it to behave the way I want. I am close, but if anyone can shed some light on which settings are the most important, and while the help manual does an ok job telling which slider does what, I'm still struggling getting the amount of transmission right.

I can get the plastic to look good unlit, but as soon as I turn the LED's on underneath, one of two things happen-

1) they blow  out and lose the color in the center of the hotspots. The areas in between the LEDs look good, with the proper amount of falloff from the led growing dimmer., but the center of the LED washes out, as if its too bright and looses color.

2) Drop the intensity of the LEDs down to where the center of the LED hotspot looks good color and saturation-wise, but there isn't enough light transmitting through the plastic to fill in green in between the LED's.

I've thought of and tried to just color the plastic green and use the LED's to add the highlights, but this unit can be any nukmber
of colors and it would be easier to just change the color of the LED, and part of my stubborn self wants to get this operating properly instead of cheating by coloring the plastic.

[DriesV]

Hi Matt,

I will give it a go.
We will definitely want to do a proper tutorial/webinar/documentation on how to use Cloudy Plastic "right".

So the intent of this design is that the top translucent part is more or less evenly/uniformly lit?

Dries

[mattjgerard]

the top image is the actual photo of it lit, green, but with higher intensity above the LED's (bright spots). so not really evenly lit.

Evenly lit would be easy, we have other products that are very  evenly lit, for some reason this one was designed to be like this, with bright spots where the LED's are.

And the center part where the icon is, is a bit darker. I think there is supposed to be a raised area that is blocking the light from getting to the center a bit, where the touch sensor inside would be.  This is a prelimieary CAD drawing, so the guts of the unit are still in design. We just have a hacked together prototype.

So, in short I need to get it to look like the top green image.  The last image is what I've been getting in KS7.

[DriesV]

Got it. On it.

Dries

[DriesV]

OK, here is my take on this...

For applications like this you can tweak the cloudy plastic and the lights all day long and you probably could get very close. (Btw, I attached my version of the scene.)
However, to deal with the "burns" of the lights in the material you would really need tone mapping.
KeyShot 7 doesn't have custom tone mapping, but this capability is planned for KeyShot 8.

My best suggestion right now is to render to a 32 bit format (EXR, TIFF or PSD) and then do the tone mapping in Photoshop using the built-in tools or one of the many tone mapping plugins available.

Attached is an example to show the difference between a straight render and a tone mapped image. I used a 32 bit PSD rendering as input for Photoshop.
Tone mapping can really make a huge difference for these kind of scenes.

I hope that helps.

Dries

[DriesV]

A super quick (and relatively dirty) way of doing this in Photoshop is to do:
Image > Adjustments > HDR Toning > Method: Highlight Compression

This will already dim the burnt areas greatly.

Dries

[Chris@SRBTECH]

Hello,

Thanks so much for posting that information. I've been trying to get a decent render of our products (signs that use tritium lights for illumination) and I've been having similar issues to the ones mentioned above when trying to re-create our diffuser materials, it just doesn't look 'real'. 
Is there any chance you could post a tutorial for that translucent material and the method for tone mapping in photoshop?
I've attached a couple of actual photos of our product to give you an idea of what I'm trying to achieve. The material is the clear area that the light shines through, although It's not the same as the material being discussed in this post, it poses similar problems being that it is back lit.

I am new to KeyShot, but really looking forward to learning what it's capable of!

Thanks!
Chris

[mattjgerard]

I did a bit of reading on Tone mapping, and its a pretty obscure thing at this point, with no real explanation on what is happening or how to use it. Sort of like when HDR processing for photos became all the rage, people were doing it without really knowing how it was working or how to tweak it to make the image look the way you wanted.

Thanks Dries for this info, we did get past this product, but there will be a ton more of this sort of image for similar products, so we will be playing with it more.