Physical sky with stars and clouds



I cannot show both clouds and stars together in the physical sky. When I change the time from day to night I see only stars, not clouds. When I change it back to day, stars disappear and clouds appear. Is this how it works or do I miss something? I just want to create a black sky with colorful clouds and bright stars without using any plugins.

By the way, what is sky objects in physical sky?



Have you tried … Sky … Example Scenes … Bright Night ?


Thanks for the suggestion. This does not work for me. I need pure black sky and neon colored clouds with bright stars. However, whatever I tried, either the clouds are very light or the stars disappear.

Actually, I achieved pure black sky with colored clouds but I cannot add stars in the physical sky.

Is it possible to add anything behind the physical sky? I tried to add stars seperately, but it seems like the physical sky is always the furthermost.


Your answer is to do this in a compositor having rendered out stars and coloured clouds as separate passes.


You could put clouds and stars on individual planes …


Thank you. Are the clouds from the physical sky? Could you please share the project file?


Star Bkg and Clouds are from google images … there is no Phy s Sky … just alpha’d planes
and landscape for dark foreground images.


How do you render the alpha channel with the physical sky? When I render it, the sky is ignored and it is all black.


I have no idea how you setup your scene ?
Upload your scene and I’ll look at it.

Example below is PS, Star jpg on plane, and Cloud with alpha, lum and trans
so you see stars behind cloud.


I used physical sky to generate clouds. I don’t want to replace it with images, because they are perfectly shaped for the job. I just want to add stars to the black sky. But I cannot do it. This is very simple and it is not possible in a program elaborate like Cinema 4D. I don’t understand.

Anyway, I decided to try this in compositing with After Effects. But I cannot render the physical sky with alpha. It is completely ignored. So, I cannot put stars behind the clouds. Why? Is there a setting?

I cannot upload an example. It says new users cannot send attachments. :frowning:


Since the clouds are bright you can make a pseudo alpha channel from them by desaturating then raising the contrast until the image is B&W.

Are you new to compositing? It’s a fairly simple task to ADD or Overlay the stars over the clouds and use the pseudo alpha channel to knock out the stars behind the clouds if needed.


Yes I’m new. Just started working on very recently for a personal project. I tried creating alpha of the clouds and put stars behind but did not like the result because it messed with the colors. I liked your idea. I will try it and I’m sure it will work better. Thanks.