Making Light Radiate from objects

I’m making a solar eclipse. I want it so that the sun has a glowing, radiating effect. I tried changing the “emit” bar in textures, but I want the light to actually make it glow, and effect area around it, not just light up that one object. Help?

This is a post effects, either achieved in the blender compositor or an external app.

Here’s a BlenderGuru tutorial on the compositor and a similar effect. :slight_smile:

Such effects are generally done in the Compositor – check out the “Glare” node, among others. You can also create a texture with alpha that imitates the rays you want and set it in position to surround the sun object, then set it up to track to the camera so it always faces it head on, if you are animating. You can use a movie file for the texture if you want the rays to change with camera angle.

This file I put up on BlendSwap uses yet another method you might be interested in, more of a glow than rays, but perhaps it will spark some ideas.

Will the compositor work for animation?

Yes, it’s designed for that.

I’m trying to use the follow the blender guru’s tutorial, but I’m getting stuck because when It previews the sun, it just shows darkness, and in the metrials tab, it says “no meterial node selected” I don’t know what to do. Also for the texturing on the sun I’m using an unwrapped image, if that tells you anything.

Simplest is to create a ‘stand-in’ object for the sun, something white/shadeless, then rendering that on it’s own layer… :slight_smile:


I put another uv sphere in different layer. Made it shadeless. Changed the render layers as the video instructed, rendered, and added these nodes. Nothing is happening to the sphere. :frowning:

Ignore the facebook window. Haha

Might be you need a backplate, you’re compositing on top of nothing… (can’t guarantee that’s your problem though, but a first step)

And I always try to ignore Facebook. I never succeed though, but at least I try. ;D

In the Glare node, you have Threshold set way above 1.0. Since 1.0 = pure white (or nominal max value for any pixel of R/G/B), you’re asking the node to act on values that do not exist in the image, so nothing is going to happen. Set Threshold to between 0 an 1.0 and you’ll get the filter to work.

I think that the Threshold field will accept a value > 1.0 because in some Compositing setups, the pixel values can add up beyond 1.0 and the node has to recognize this.

Okay so the pic of my compositor is in the here. I like the way the sun is glowing, so how do I get it all put together so that the sphere with this glow is in the same layer as my sun, so the sun looks like it’s glowing?

Attachments


From here you use a color->alphaover-node and place the sun on top of your backdrop. :slight_smile:

I added the node… but i’m not really sure what to do with it xD

An alpha is a 4th channel (rgba = red+green+blue+alpha) in black & white (greyscale) which represent opaque and transparent areas of an image. Where there are no objects in a scene, Blender automagically creates an alpha. This alpha is what you use to put something on top of something else though keeping the transperancy. The node used to do this is namned ‘alphaover’. Here’s an example of it used in a composite.

Edit: You will need to start thinking about this as layers. In compositors like After Effects it’s pretty obvious as layers are actually represented by layers, as in Photoshop, but in a node based compositor as Nuke or Blenders compositor, you need to think in terms of layers and stuff on top of other stuff even though it’s represented by the nodes…

As a sidenote I must admit personally prefer layered compositors like After Effects for most work, but there’s no question that node based compositors are easier when it gets to complex comps… When you got a lot going on, then layers based compositors become over crowded and it’s hard to keep it all in order…

Another option for combining the imagery is a Color>Mix node. Mix is the default blending mode, but you can also use Add or Screen or Lighten, or whatever mode works best for your concept of the image.

Best way to get an idea of what the nodes can do is play with the various options and parameters.

My friend is helping me with this, and I’m using the mix node. Thanks for your help guys!

One more thing… I gave the sun the effect I want it to have… but It also gave it to the moon… so I brought the moon into layer one, and kept the sun alone in layer two. How do I set it up so that I can render both layers simultaneously, while keeping the glare ONLY on the sun?