The TCL/TK tutorial is designed so that even beginners in TCL/TK and VTK should be able to pick it up easily.
Part 1: Installation is an easy to follow guide to installing the core VTK packages and data as well as the TCL/TK package and language itself.
Part 2: Visualizing Molecules will show some of the flexibility of this powerful tool.
Part 3: Visualizing Terrain teaches interfacing with Terragen, a powerful terrain generator.
Part 4: Interactive Visualizations shows how to use TCL/TK keyword in combination with VTK to enable manipulation of vizualizations on the fly.Part 5: Geometric Shapes and Texturing has code snippets that demonstrate the visualization of multiple geometric primatives.