State of the Art of Ground and Aerial Laser Scanning Technologies for High-Resolution Topography of the Earth Surface

Airborne and terrestrial laser scanning (respectively ALS and TLS) have become, in the past years, well established technologies for measuring spatial characteristics of objects on the earth surface and the geometry of the earth surface itself. Research and development have created the technology for providing a market with a wide choice of instruments. The distinctive data produced by laser scanners is a 3D point cloud with high-quality positional and return-related information (3D coordinates, reflectance, return echo ordinal number etc...). Partially obstructed impulses give multiple returns, thus important added value to the dataset, by penetrating gaps which are present in certain elements (e.g. vegetation) and reflecting the ground surface as last return. In the last years sensors have been developed which provide the digitization of full return waveform. This capability provides significant data for sophisticated classification and reflectance calibration of the targets and a practically infinite number of return targets per emitted pulse (Briese et al., 2008). Terrestrial and airborne laser scanning share many features related to scanning mechanisms and processing methods whereas they also differ in terms of accuracy, range, data-capture modes and project size (Vosselman and Maas, 2010). In this presentation a comprehensive overview of airborne and terrestrial laser scanning technology and processing is presented focusing on aspects related to high resolution topography of the earth surface. Accuracies, error budgets, and processing methods to improve and assess quality of the scan are reported to give an outline of the potential of current laser scanner sensors for providing high resolution models of the earth surface.