Stars …
Any tips or techniques for making stars look realistic from a matte painting. Or just a simple photo of a star field.
I’ve created a 3d environment that uses matte paintings as a background, very simple nodal pan … but the backgrounds still look like photos … they lack that … special twinkle … or something to bring them to life.
Thanks
Dave.
Hi there Dave,
They’ll just need some kind of very subtle flickering, or some kind of “movement” similar to flickering but maybe not as fast as a typical flicker.
Try this, assuming your stars on on their own layer. Duplicate the layer, put it in “add” or “Screen” mode, and add a fast or Gaussian blur. Then above that layer, create a new solid, color doesn’t matter. Add a “fractal noise” to that solid layer, and dial down the scale, and maybe turn down the complexity a tiny bit. “Alt - click” the stopwatch next to the evolution setting (this allows you to enter an expression to control that parameter), and type
time*100
Now the noise animates. Later on, if it’s going too fast or slow, try numbers higher or lower than 100.
Now precomp this layer, call it something like “noise map”.
Below this layer, on your blurred star layer, change the track matte setting (right to the right of the blending mode setting) to “luma”. This will only show the blurred, glowy stars where the noise pattern is white, and because it’s in motion, it will be “flickering” and oscillating. Of course, adjust the speed, opacity of the glow layer, amount of blur, all that stuff. You could even duplicate the whole setup, offset the noise map layer (so its not the same as the first noise map layer), and maybe do a different set of settings, like smaller tighter glows, or maybe throw a color balance on and introduce some very slight color.
Just some thoughts…
If you have Trapcode Particular you could create a Solid and apply it and set the emitter to box and adjust the X,Y,Z fields. This way you actually have a 3D environment of particles if you want that effect. Or you can create a layer and push them way in the background, and that way if you turn a bit they should still be there as well. To get them to look more like stars you can add a starglow and adjust the settings, that plug in is also a product from trapcode. I would set the random opacity and size and such to give you some depth. Or if you are looking for more of a stylized star you can create your own “sample” star and use it as a custom particle.
I am not sure how advanced you are getting but there is also a way to link cameras if you go the route of the custom particle. You may want to search camera linking in AE, I don’t know the expressions off hand. Good luck and hopefully that gets you a start on what you are looking for.
Let me know if you need any other help on it and I will see what I can do. I am more of an AE user than a 3D artist, but everyone here is so helpful with 3D this is kinda the only forum I feel like I can give advanced knowledge in. Look forward to seeing it.
Ok, thanks for the in depth explanation, but for a matte painting … i mean, a 2d photo of a star field. I have a simple image of a star field, and want to bring this to life, i’m not so much looking to recreate a star field in AE, just bring an existing image to life.
Thanks Sean, the stars are not on a separate layer, just a matte painting comped together from various NASA images.
Dave.
It would still work. Make a quick garbage matte of the sky area on the duplicate, and put a “levels” effect on it and make the sky blacker until it disappears in “screen” or “add” mode. Then do all the other things. 
I could whip up a sample AE project for you if you’d like.
Maybe your starfield photo does not look like a movie frame because as a still picture it could be exposed for seconds or longer to get a very detailed, bright result.
When you film with a star field in the background, I guess from the star field not much more than just black would end up in the recording, as the foreground is much brighter than the sky. So maybe you just need some color correction to let most of the details of the sky disappear?
Could you post the pic? That might help us out a little bit. If you have an existing still you could add a fractal noise and adjust the scale and add a small evolution to it to give it a little bit of movement. You can adjust the contrast and brightness to get the desired effect. You could also maybe duplicate the layer and set it to add to brighten up the stars and then adjust the transparency or add a glow and adjust those settings. This way you can give the stars a subtle variation in brightness. You could maybe add an optical flare or a lens flare into the foreground (maybe a feathered solid with a glow may work too) to give the camera a vibe that you are catching some rays from a star that is close by or something as well? Hope that helps!
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