Developing & maintaining a VR system is a very difficult task, requiring in-depth knowledge in many disciplines. The difficulty lies in the complexity of having to simultaneously consider many system goals, some of which are conflicting. This book is organized so that it follows a spiral development process for each stage, describing the problem & possible solutions for each stage. Much more hands-on than other introductory books, concrete examples & practical solutions to the technical challenges in building a VR system are provided.Part 1 covers the very basics in building a VR system & explains various technical issues in object modeling & scene organization. Part 2 deals with 3D multimodal interaction, designing for usable & natural interaction & creating realistic object simulation. A CD includes the codes developed in stages from examples that appear in the book. Primarily written for first level graduates, advanced undergraduates & IT professionals will also find this a valuable guide.