Airborne laser scanning – high quality digital terrain modelling

After a short introduction into the Airborne Laser Scanning (ALS), the sampling<br>process and a brief comparison of ALS with other data acquisition methods, the paper<br>focuses on the generation of high quality digital terrain models from ALS data. In the<br>first part the hierarchic robust interpolation method for the automatic filtering and<br>classification, respectively, of an ALS point cloud into terrain and off-terrain (points<br>on buildings or on the vegetation, etc.) is presented. Then, an approach for the modelling<br>of linear features, such as break lines, based on the ALS data is described. Based<br>on the feature lines and the classified terrain points a high quality DTM can be determined.<br>For many subsequent processes the data reduction of the detailed DTM is<br>essential in order to handle the large amount of data. Therefore, the paper presents a<br>data reduction method that guaranties a certain DTM representation quality. Next to<br>the presented algorithms, for each of the mentioned topics, references to other published<br>methods are provided. Furthermore, beside the description of the algorithms,<br>practical examples demonstrate the results of the algorithms. At the end of the paper,<br>an outlook section discusses the advanced possibilities of DTM determination based<br>on full-waveform ALS data.