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Transparency mat killed my sky ?

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Do you ever get those days where you start thinking 'looks like I'll have to re-install C4D or Windows or both' ? Recently I had a problem with a disappearing sky, and after trying everything possible, I was about to throw in the towel when I found that disabling transparency on one of the mats fixed it. Sounds so unlikely that I did a screen grab -



buildings from Pixel Lab, helicopter from free3d.com


here's a WIP



when you have eliminated the impossible, whatever remains, however improbable, must be the truth - Sherlock Holmes

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Just as a matter of curiosity...does switching off/removing one of the Skies also resolve the problem?


Just wondering if the Transparency settings with Total Internal Reflection and Exit Reflections ticked on together with having two Skies is causing calculation errors. I realize you have used Composition tags on both Sky Objects, but I'm wondering if it is still involved in light/reflective calculations for the windows. Short of totally disabling transparency, does unticking Total Internal Reflection and Exit Reflections resolve anything? Not that any of these combinations should cause the issue of course, just curious.


I like your helicopter rig too. Good work as always and thanks for sharing your findings and wisdom for error checking.

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You have 2 physical skys, 2 suns, and a sky object.  I'd just guess that for the sky object you are actually using to be seen it has to be seen though 2 physical sky objects right now.  This combined with the transparency level on the buildings makes the transparency level too high for the sky to be seen in some cases.  To add to the complexity 2 physical skys and sky object might occupy the same space and they could be overlapping like polygons on the exact same spot.  Two polygons on the exact same spot will do this because c4d does not know which it should display first.  In other words you are kind of gambling as to weather one sky or the other will be displayed.  To fix this try deleting the other skys not being used.  If there is still a problem try upping the Ray Depth under the Render Settings > Options.


At least that is my guess.

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