The emissive map is a texture that can be used to make certain parts of the model glow, just like the emissive property does for the whole model. This is easier to understand by looking at an example. If you open up the 15-emissive-map.html example in the browser, you will see two lava-like objects. With the controls, you can limit the light emitted from the lights, and you can see that even with low lighting, the objects still glow:
When you look really closely, though, you might see that while the objects seem to glow, the objects themselves don't emit light. This means that you can use this to enhance objects, but the objects ...
