Towards True Underground Infrastructure Surface Documentation

Underground infrastructure becomes more and more important in urban development. Building and maintaining tunnels typically involves three phases: construction, monitoring and repair. Throughout all three phases engineers increasingly demand a visually and geometrically exact digital representation of a tunnel surface involving both high resolution imagery and laser scan data. These requirements pose a challenge to all phases of the visualization pipeline. After retrieving geo-referenced geometric and image data with a surface resolution in the range of 1mm and better, novel processing and mapping techniques are applied to enable a fast and efficient rendering while preserving high sensor data quality. Visualization of such data requires handling huge amounts of 3D Points, high-resolution textures and additional graphical elements that explain the context of the displayed data. Without additional processing the sum of this data exceeds the capacities of both the graphics card and the main memory. The paper describes how a tunnel of several kilometers length is digitalized by range laser scanners and cameras, processed into an efficient data structure and finally integrated into a fully interactive 3D visualization combining multiple data sources for real-time display and interpretation.