Week 10 - Emissive maps

What are Emissive maps?

Basically an emissive map is purely used to emit light or more light from a light source within a 3D asset to help it look more luminous and much more realistic to make it look as if the lights are actually on. It helps make the asset glow. With emissive maps you can emit light from anything which you want to be lit up or have a glow and anything that you do not want to emit light should always be black otherwise you will have parts emitting light that should be.

The image above is a good example of how emissive maps work. As you can see with the emissive map applied you get a massive difference with how much light is emitted and it makes it look so much more realistic.


As this is my first time working with emissive maps I have been testing how to use them and how to apply them to the diffuse texture for them to work. Looking at a number of tutorials online to help me understand how I set it up in order for it to display on the asset, I finally managed to get it working which seems straight forward once I knew how to do it.

This is what I did and this is the layout of how to get the emissive to work on the asset. You make a diffuse texture then you make an emissive texture in which you make everything black except the stuff you want to emit light.

Next you open up the diffuse texture material in UDK and you drag the emissive texture onto the diffuse texture material. You then add in a multiply by dragging it from the right tab or holding 'M' on the keyboard and clicking in an open space which brings up the multiply box. Then you add in a new constant which is right click add new constant.

Once you have all the main bits you then link them up to there correct links. Diffuse map links to diffuse.

Then you connect the emissive map to point A of the multiply and the constant to point B, finally connect the multiply to the emissive link.

Once you tick the box it should work and from there you can change how much you want the light to emit and how much glow to want on the parts you are lighting up. To do this you simply click on the constant and then change the value in the properties higher or lower depending on how bright you want the light to be emitting.


Here is a quick test I did to see if it worked for me (image below).

As you can see that it has seemed to work fine for me and emits the light exactly how it should be emitting.