So after 2 years of blender use, I have finally begun to understand and use the compositing node system. I’m having a little trouble getting this effect, hope someone can help me out!
I have an earth-textured sphere that I want to put a blue glow around the edge. I thought the best way to do this would be to take the object index mask for the earth object, color it blue, blur it, and layer it behind the “real” earth. I’m having trouble changing the mask’s color, and also I’m not sure how I would go about putting the blue glow behind the earth, although I think with some tinkering I should figure it out.
The reasoning of how to go about doing this sort of effect seems plausible.
Considering you setup, however, you don’t really need the id mask for this, it’s redundant if the only object in the render layer is the globe. In that case the alpha channel data would be sufficient.
You just need to thread the alpha channel (or the id mask) to the fac socket of the mix node.
I took a stab at this a while back. The problem I ran into was that glow does not actually “grow” any pixels around your ID mask. So I mixed together spheres from two different scenes. The corona scene sphere is a little larger and that is how I accomplished the expansion for the glow. I was looking for a little more than glow. I wanted the sun corona with animated tendrils. This scene was as close as I got. But you can simply apply a solid color ramp to the secondary sphere (I applied noise) if you want a solid glow.
Play with the RGB curves shape to re-shape the glow.
Also, feel free to pull down my other planetary attempt here:
For the glow I used a bunch of halo lights centered inside the sphere. By adjusting the clip start and end you can control the glow of the planet.
blendercomp: thanks, i thought of that, but this is an animation, so other objects come into the scene.
Atom:Yes, but that isnt exactly the effect i’m looking for. thats more like, as you say, the sun’s corona, as opposed to the earth’s thin blue glow around the edge.
Thanks, blendercomp, but that seems like overcomplication. did you even use the Object Index Mask at all? sorry, havent used the nodes in 2.5 yet…
let me try to simplify my question.
Basically, how would you go about coloring a single object via the ID Mask Node/render pass?
That was my point, don’t bother with the ID mask. I just used another scene with a sphere a little bigger. My node setup is pulling in output from two different scenes and compositing them together for the final. I made my sphere in the other scene a bit bigger (that is how you control the size of the glow). Also, that is why I mentioned you could just use a solid color on that second sphere if all you want is a glow. The corona was generated because I choose noise instead of a solid. Edit the colorramp node to change the color of the node to blue instead of yellow.
Atom: Thanks, now i understand what you did…but still, doesnt that sound more complicated? and i do want to fully understand how to use nodes…ID Mask seems like a useful tool.
did you even use the Object Index Mask at all?
no, I used a photo of the moon I took last summer, pulled a matte and use that for the glow. It’s proof of concept, not the exact solution to your problem. It’s the only relevant noodle I had available.
sorry, havent used the nodes in 2.5 yet…
let me try to simplify my question.
Basically, how would you go about coloring a single object via the ID Mask Node/render pass?
From what you said I understood that you didn’t like Atom’s suggestion because of the size of the glow. Mine somewhat takes care of that. Considering your setup, what you need to do is this: #1. glow the object (using a blur radius of about 20 or whatever suits your purposes) #2. use the id mask channel info and connect it to the factor socket of the mix node.
I guess that should do it.
