What you will need
- Maya / Blender
- Photoshop / Gimp
- XNormal (a free & very powerful map baking tool). This tool is windows only. A mac alternative would be Substance-Designer
Basic principle of the technique
- XNormal will be used to extract curvature information from the model. This information is determined from the surface normals. As such, normal direction and hardness will effect the final result.
- This map will be used as a mask for your edges
- If you are not familiar with the following topics please give the articles linked below a read before continuing:
Step 1: Prep the model
- Create a model with bevelled edges and unwrap it. In this case I have softened the normals of the faces in the bevel, and left the other faces with hard normals.
- Export the model as an FBX or OBJ
Step 2: Setup XNormal
- Install XNormal and reboot if you have not done so.
- Click on High Definition meshes
- Right-click on the file column and load your mesh
- Ensure visible is ticked
- Repeat the process for Low Definition Meshes
Step 3: Baking Options
- Click Baking Options
- Set an Output File
- Set a resolution (I am using 1024×1024)
- Select Curvature Map from the list of options
- Click the green option button next to curvature map
- Set the algorithm to Gaussian
- Distribution: Uniform
- Tone Mapping: Monochrome
- Click Close
- Click the Generate Maps button
- The curvature of model is represented through the grey tone on the map. A model with more complex curvature would have a greater range of tones.
Step 4: Creating a mask in Photoshop
- Open the map in Photoshop and use the level adjustments to bring the lighter tones toward white and the darker tones to black. Depending on the map created you may want to isolate tonal ranges with the curves tool.
- Fill the transparent area with black
- Create a new alpha channel in the channels tab
- Copy and paste the map into the channel
- Ctrl-click the alpha channel convert it to a selection
- Create a new layer and assign the selection as a mask
- Fill the new layer with a texture of your choice (be sure not to accidentally fill in the mask layer)
- Select the mask layer and work into it with a textured eraser. Alternatively use filters of your choice in Photoshop on the mask selection to break up the edges.
Adding edge wear is a very quick way to add realism to models – this implementation is a particularly simple version of the process. XNormal provides quite a considerable of array of maps in its aresenal and baking out maps like ambient occlusion, world-normal, cavity, thickness etc can be used to take this process a whole lot further. If you prefer something that is even more automated, Substance Designer which I mentioned earlier pretty much automates a whole bunch of effects like this. Definitely worth checking out.