An extensible animation system is presented for creating visualizations that aid in understanding the complex interactions associated with a construction project simulation. While the focus is exclusively on construction, common features with other virtual environments make this work of more general interest.

Extensions are built on a lower-level three-dimensional (3D) animation language for continuous visualization of construction operations. The software is well structured with low-level details hidden, attention to portability and efficiency, and a clear interface for adding to the language. New language features (for example, the addition of a dump truck) may require actions for related updates at specific times (lower truck dump bed), as well as screen refresh details (drawing truck motion). The add-on interface has a mechanism to register code with the system in order to implement these actions so that updates and screen displays are properly managed. This extension process is clearly described using flow charts and simplified C code. A set of elaborate applications including a particle system, equipment motion, and collision detection are briefly described to illustrate the strengths of the approach.

The presentation is clearly written, with good use of figures and examples. The level of descriptive detail is high for a software specialist, but appropriate for readers interested in applications. While the emphasis is on a well-structured and easy-to-use system, building extensions requires an understanding of C++ and object-oriented programming.