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Alpha and Transparency overlap issue

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Vishwesh MenonAlpha and Transparency overlap issue
by on Jun 14, 2014 at 3:57:19 pm

Hello all!

First up- a big thank you to everyone on creative cow!! I've learned so much on these forums- it's crazy! Thank you!!

I'm new to C4D and am still struggling with the basics.

I'm working on a video where the environments are made in c4d (3d) and I'm animating the characters in flash and placing 2D Characters in C4D

I have two 2d Character PNGs projected on two planes and placed in a 3D environment made in C4d.

The PNGs are placed on the planes via a texture material with the PNG loaded onto the color channel and Alpha channel. No other channels are activated.

One character is placed behind a cash counter of sorts (made in C4d) with a partial glass face- so part of him should be visible through the glass.

The other character is placed in the foreground in front of the Counter.

The counter has a glass face- for this I have created a texture material with only the color channel and transparency channel activated.

I have added a look at camera Tag to the character planes.

This is how the setup looks in C4D

The problem is- This is how it looks rendered.


It's messed up! and i think I'm missing something very basic.

The space around the character on the character plane that should render as transparent (alpha of the PNG)- renders gray in color through the transparent glass- but renders transparent (as needed when not seen through the glass)

As for the Character Plane in the foreground(in front of the counter)- the alpha around the character renders fine- but makes one part of the cash counter invisible (whenever/wherever the character plane overlaps the cash counter).

I'm lost about this- have been stuck with this for quite a while- and thought i try everything i could before I post here.

In addition to this overlapping render issue- another issue i'm facing with placing the 2d characters as textures- is that- the PNG images always become darker in color than they actually are. Increasing the brightness of the lights does make the character PNG brighter- but unintentional brightens the 3d elements in the scene as well giving the render an unpleasant over exposed look (only the character seems fine- but the rest is over exposed).

I request you support.

Thanks in advance


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Adam TrachtenbergRe: Alpha and Transparency overlap issue
by on Jun 15, 2014 at 9:08:41 pm

It looks like you need to increase the ray depth in render options.

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Cassius MarquesRe: Alpha and Transparency overlap issue
by on Jun 18, 2014 at 5:30:08 pm

Do you have "evaluate transparency" option turned on in the ambient occlusion tab?

As for the darkening have you tried using the texture in the luminance channel instead of the color. It can be caused by gamma issues or color workflow settings too IMO. I usually fix in post with passes.

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Nick ShotwellRe: Alpha and Transparency overlap issue
by on Oct 14, 2015 at 1:56:42 pm

I had the same problem. "Evaluate Transparency" under Ambient Occlusion fixed it!

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