• Maxon Cinema 4D

  Alpha Channel Problem

  Posted by James Harford on September 21, 2010 at 11:24 am

  Hi guys. This is my first post, so I hope it is correctly titled etc.

  I am using a plane with an image as a material. The material has an alpha channel. The alpha channel works fine.

  But !! .. When the camera moves into a position where the sky is behind it, it replaces transparency with white!

  Here are some screen shots to illustrate the problem.

  https://img638.imageshack.us/img638/6779/3d0031.png

  https://img69.imageshack.us/img69/6779/3d0031.png

  Any advice/help would be greatly appreciated!

  Thanks , James

  Armian Eteroxee replied 15 years, 2 months ago 4 Members · 8 Replies
• 8 Replies

• 

  Adam Trachtenberg

  September 21, 2010 at 3:20 pm

  What are you using to create the sky background?
• 

  James Harford

  September 22, 2010 at 8:53 pm

  Thanks for the quick response Adam. The sky background is made from a jpeg material dropped onto a sky object ?

  Many thanks,

  James
• 

  Adam Trachtenberg

  September 24, 2010 at 4:20 am

  That is really strange. When you say sky object do you mean the one that’s in the icon palette with the camera, lights, etc., or the sky object that’s in the Objects>Sky menu?

  Are you using an environment object with fog? Any post effects?
• 

  Armian Eteroxee

  March 7, 2011 at 4:45 pm

  Hi!

  I have the same problem. I made an alpha chanelled plane (with a tree on it). I put fog, and hair (grass) behind it. Problem is, that grass can’t be seen behind the plane, and fog begins far away. Oh, and I made the image with Photoshop, saved as .psd with alpha chanel. I would like to use it to make a single image.

  Here is a picture
  

  I know, it’s a forum, but please, reply fast!
  Thanks a lot!
• 

  Brian Jones

  March 8, 2011 at 2:46 am

  you can get the grass back by setting Render Setting/Hair Render/Render/Render to Raytrace (instead of one of the Rasters) but that won’t help with the interaction of the alpha (or transparency) with environmental fog or channel fog. You could use a really big visible light with No Illumination checked but while that is similar to fog in it’s look it’s harder to control the falloff and if you grass is tall enough you will see where the alpha is in the grass (instead of in the fog). You could stay with raster with the Hair too.
• 

  Armian Eteroxee

  March 8, 2011 at 7:30 am

  Thank You very much Your quick reply!

  But I hooked up with this render thing. I selected the ‘Render to Raytrace’ option, but then it didn’t render the grass at all. What else should I set to make it work?

  Cinema4D 10.111

  Thanks again!
• 

  Brian Jones

  March 8, 2011 at 3:45 pm

  ah, 10.111 I tried in 10.5 (the oldest I still have installed)and the behavior is completely different than in 12. I don’t know of a fix other than to stay with raster for hair and give up environment fog and try to use a visible light with no illumination and the falloff for the Visible set to something large (ie 10000). More tricky than fog but it’s similar.
• 

  Armian Eteroxee

  March 8, 2011 at 4:26 pm

  I made it combined with PhotoShop. First I rendered the scene without the alpha chanelled plane, and then I pasted the layer in PS over it. It’s an interesting problem, at other posts they say, that it’s a known disadvantage of this software. By the way I like it. Oh, and sorry not to mention the version number at first!

  If I will be ready with the homepage, I make, i’ll send You its link.

  Thank You again!

  Best wishes, Eteroxee

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