Adding Emissions to Custom Textures

Using Photoshop and Blender to create Emissions maps for custom textures for use in Unity

In the last article, I looked at modifying pre-built textures using Photoshop for use in my Sci-Fi control room in Unity. Today, I’ll be making parts of those textures glow by creating emission maps to be applied in Unity! I’m going to be using a combination of Blender and Photoshop to do this!

What is an Emission map?

Simple Emission texture using Photoshop

Now with the image open I want to create a new Layer in the image this will act as my base layer. I’m going to fill this layer with black.

Next, I’ll hide the black layer and create another layer above the black layer to hold the white/gray portions of my emission map. I hide the black layer so I can still se the underlying texture map for selecting the areas I would like to glow. In this case. The transparent areas of the image are the areas I want to create an emission channel from. Since that is the case I’ll use Photoshops “Load Selection” Option. First, I want to make sure I have selected the later with my original texture in it. Clicking Selection > Load Selection presents me with the load selection dialog below. I’ll select the Transparency layer and choose to invert the selection by ticking the Invert check box. If I don’t select the “Invert” checkbox, Photoshop selects all of the non transparent pixels in the image and I would have to press Shift + Ctrl + i to invert the selection and choose the transparent areas I wanted. The check box in the “Load Selection” dialog just saves me the extra step.

With my selection created I now choose my new top most layer and use the paint bucket tool to fill in the selection with light gray or white.

I then turn back on my black layer and press Ctrl + D to clear my selection. Now that I have my emission channel ready I choose File > Export As… and export the image as a PNG file into the same folder as the original albedo texture. I also save my Photoshop file for future reference or use.

Switching back to unity, I can now find my Material and enable the emissions channel. Then I’ll drag my newly created emission map into the slot for an emission map on the object.

Emission texture using Blender

For this method, I start by opening Blender, my current modeling software of choice. Once I have the software open I delete the light, cube, and camera from the default scene. Next, I click File > Import > FBX (.fbx), navigate to my projects Assets folder, select my FBX folder where I store my models and select the 3D models for objects that I want to add an emission channel to. In this case I’m importing my Sci-Fi Column pieces. Since I imported 3 files Blender has stacked them on top of each other at the origin. I use the Move tool to space them out.

With my models now in my scene, I make sure they are both selected and then I click on the UV Editing Tab to open the UV editor.

Next I make sure that “Face Select” is turned on, and I select the faces that I want to glow. This highlights where those faces are in the UV map.

Now that I have my faces selected in my UV Map Editor, I want to export that map so that I can bring it into Photoshop to finish creating the emission map from it. I can do this by selecting UV > Export UV Layout in the UV Editor panel.

Now that I have my UV selection saved, I open it in Photoshop, and follow a similar process as I did for the simple selection. I create 2 layers, one to hold the black non-emissive selection and the other to hold the emissive selections. Using the “Magic Wand” selection tool in Photoshop, I click in the transparent section of the imported UV Map and then invert the selection using the Shift + Ctrl + i keyboard shortcut. I then fill in that selection using the Fill tool located at Edit > Fill and selecting to fill the selection with a solid color. Once the fill is complete I deselect my fill with the keyboard shortcut Ctrl + D and turn back on my black layer.

With my emission texture created I now export the image as before, with File > Export As… and save the PNG back into the same folder as the albedo texture for these models. I can then head back into Unity and assign the emission texture to the emission map slot of the material used for these column models.

Look at those emissives!

Next Time!

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Unity Game Developer, Software Engineer, Gamer, Musician, and Father. Christopher is a creative that enjoys a challenge and loves coding.

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Christopher West

Unity Game Developer, Software Engineer, Gamer, Musician, and Father. Christopher is a creative that enjoys a challenge and loves coding.