Visualizing laser scanner data for bridge inspection

Laser scanners are being used for the geometric assessment of bridges due to their ability of capturing dense point clouds about an environment very quickly. As important as the geometric data collection, is the timely and intuitive interpretation of such point cloud data (PCD) enabled through effective visualization techniques. In this study, using PCD of a highway bridge, we evaluated different 3D visualization techniques to support a variety of bridge inspection tasks. The visualized geometric items include a) points, b) lines, and c) surfaces. The visualization techniques evaluated for these items include: a) wireframes for visualizing surfaces, b) cross sections for visualizing 2D profiles, c) colours for visualizing values of interest from virtual inspection point of views (e.g., deviations), d) lighting directions for rendering 3D scenes, and e) contours for visualizing statistical data patterns. The evaluated techniques show differences in supporting the visualization of geometric data through better utilization of the raw data. This paper discusses these differences in visualizing geometric items to support a variety of inspection requirements of bridge inspectors.