Dirty Shadows Around Raised Buttons

[Robb63]

I am rendering a silicone overmolded piece that has raised icons. As you can see in the image, the shadows around the icons looks more like dirt than a realistic shadow. Any ideas what i can change to fix this? This is rendered at 256 samples

I seem to remember this coming up before, but a search didn't reveal it.

[bdesign]

Are you by chance using the "All White" or "Startup" HDRI Environment? It looks like a low contrast HDRI is being used (?). Whichever map it is, try increasing the Contrast under the Environment tab, or try an HDRI that has greater contrast by default.

Eric

[bdesign]

...Also, if you're using the Advanced Control rendering method, try disabling the Global Illumination Cache.

Eric

[Robb63]

Thanks for the suggestions guys.
It wasn't the startup environment, but I've tried several different HDRI's  from 2000 x 1000 up to 6000 x 3000 with increased contrast,  and tried disabling GI in advanced. Still getting the same result unfortunately.

[bdesign]

What type of material are you using? Is there an Occlusion node anywhere in the node network? Do you have physical lights in the scene with a high radius value? Are you rendering with Interior Mode? Could you post a screenshot of your material settings to maybe help identify the issue? I'm just throwing ideas out there...

Eric

[bdesign]

Hey Robb-

After doing a bit of testing , I'm guessing that you're using the Translucent (Advanced) material on this geometry (?). I also have a feeling that the buttons are separate geometry intersecting the base, but it's difficult to tell from the small sample image. I put together a couple of quick mock ups of your objects- one with separate base and buttons, one with booleaned base and buttons, and rendered each with both the regular Translucent and Translucent (Advanced) materials (same colors and other matching material properties). The regular material cleaned up much nicer around the small details- you can see quite a difference between it and the advanced material, as well as a difference between the separate and booleaned versions- especially with the advanced material; the difference is very subtle with the regular Translucent. The four images below are:

1. Separate base/buttons, Translucent (Advanced)
2. Booleaned base/buttons, Translucent (Advanced)
3. Separate base/buttons, regular Translucent
4. Booleaned base/buttons, regular Translucent

Each rendered with 128 samples, no GI.

Eric

[Will Gibbons]

As bdesign's findings support, when using transparent and translucent materials, your geometry and how it interacts with neighboring geometry definitely affects how your materials appear. This is because light is moving 'into' or through the material, rather than just being reflected off the surface.

Nice study @bdesign

[Robb63]

Thanks for that in depth study bdesign!!
I'm actually using the standard plastic material (not translucent). But after seeing your studies, I am wondering if the data, or imported image quality settings might be to blame?
The data came right out of SolidWorks, but the engineer who created the data had the image quality turned way down. The icons are part of the main body though.
I'm cleaning the data up in Rhino currently, and will post my results once I get a chance to try it out.

Thanks for the help, I really appreciate it!