Using Open Web 3D Services and X3D for Interactive Virtual Globes

Abstract

This chapter discusses how the scene graph concept, originating from computer graphics and graphics editing tools, can be used in a 3D Geoweb environment. A concept for developing and setting up Virtual Globes is described, which merges spatial data infrastructures with computer graphics technology in order to create a global coherent framework for accessing and displaying 3D assets. Using scene graph data structures for encoding, transmitting, and displaying city and landscape models imposes new requirements to geospatial data processing and analysis. Supporting transformations between coordinate reference systems is essential for geospatial system integration. They are described in detail in this chapter including matrix calculations. Streaming formats that are used to transmit 3D geo data to the consumer also need to support the scene graph concept. In this context, a Web 3D Service (W3DS) interface is used for streaming X3D encoded data in distributed web environments. An implementation of a Virtual Globe based on freely available data sets from OpenStreetMap and NASA is described as a result.