How can I make a part of a texture glow?

Question

I need to make a part of a texture glow slightly. Like Killer Crocs eyes (see image below)

How do I do this?

I added a black and white texture (white for the glow. But then this happened.

There are strange colors around the eyes. Also how do I change the white glow to red?

Answer 1

You have 3 options to create the glow:

1. Define the glow with a texture and use that as Emission shader added to your model. The glow haze has to be "baked" into such texture. Limitation: There is no glow outside of object's silhouette.

   This is our starting point:

   

   We need to define the glow with a glow texture - it should look like this:

   

   • define the color of the glow (you can have different color glows in one texture)
   • size of glow haze with amount of blurring
   • and amount of glow with brightness

   
   Here we made both eyes glow. The emission is added to your previous shader:

   

   Keep the emission strength between 0 and 1.

   Advanced:

   You don't have to necessarily make a glow texture, it is possible to extract it from your color texture with nodes inside Cycles to make a procedural glow:

   Let's make a basic Color Key node based off color difference:

   

   Next we can key out multiple (or single) colors into a mask and use it on the original color texture to extract areas to glow (example with eyes and teeth):

   

   Now only the glow haze is missing, which is easy to do. Get the ImageBlur node from B°wide node pack or make it yourself:

   

   It is noising the image mapping vectors, so use like this:

   

   Now we just need to combine (add together) the un-blurred and blurred to get our glow (only kept the eyes and deleted the teeth - was just too many nodes to show):

   

   Use with your shader as before - this is the procedural result(s):

   

2. Render a mask (with render layers for example) and add the glow in compositor with Glare node set to Fog Glow. There will be glow outside of object's silhouette but the result won't be physically correct.

It is very similar as with the cycles procedural nodes, you also don't have to render some glow mask but instead key it out from colors (which might not be accurate though because lighting can affect the model colors).

3. Add a volumetric fog environment into your scene to get physically correct glow. Your eyes have to have emissive material also but the glow haze is not painted in.

Answer 2

make another texture where all the parts that should glow would be white and the rest black. Then when making the material add emission shader and mix it with the rest using the second texture as factor. this is the node tree (and render): and this is the texture itself:

Answer 3

well if you split the textures from the face and the eyes you can simply make the eyes glow on that single texture, just by doing this.

Answer 4

Just go into edit mode select the faces you want press P select Separate Selection.

Go into Object Mode select the part you separated add a new material, add an Emission shader change the color and Strength and parent to the original piece.

That should work for v.2.7.9