@Michael, in relation to the first example, the documentation was pretty clear and straightforward. I must admit, I was pretty pleased when it all worked and the results looked so beautiful.
In relation to the texturing example I had to feel my way a bit, I searched the VTK repository to find the textures used in the picture in the article. I was also unfamiliar with the terminology. My biggest problem was finding an emissive texture so I used Photoshop to modify the VTK logo and convert it to a black background. You will see I kept the bars around the letters as they gave me an indication of the lighting colour when setting the emissive factor.
With respect to the sources used, it was interesting to do uv-texturing on the parametric surfaces. Once I figured this out, the texturing of these surfaces was easy! For debugging texturing I found your files: tex_debug.jpg and vtk_Base_Color.png useful.
I learned a lot from your well written article.
One other big bonus from the work you guys have done is that it was really simple to convert the C++ code to Python as you can see in the examples.