I figured I should try to analyze this by myself since the webpage is really gone.
I'm just doing a poor man's way of making normal maps for textures only, so don't worry about 3D models. It's all thanks to admin rights on the lab computers I'm using, I wasn't able to install those programs that generates normal maps from textures.
I figured that a normal map consists of cyan and magenta colors layered on top of each other. Here's what I did:
- I decided to use Adobe Photoshop.
- Create a new copy of the texture I was going to use.
- Change image mode to CYMK.
- Paint the yellow and black color channels to all white.
- Offset individual cyan and magenta color channels a bit in different directions and orientations.
- Re-save it as PNG.
What I got seems to work I guess. I know it's not perfect for a terrain texture, but it still gets the job done.