Registration Quality - Towards Integration of Laser Scanning and Photogrammetry
Laser scanning and photogrammetry are powerfil 3D data acquisition methods providing both overlapping and complementary information. Currently, integration of laser data and images provides the most complete information for various surveying and 3D modelling tasks. However, this integration requires that both data sets are accurately oriented to the same coordinate system. In 2008, EuroSDR launched the project 'Registration Quality - Towards Integration of Laser Scanning and Photogrammetry' in order to collect knowledge about current registration methods and their performance. The project attracted the involvement of numerous research institutes and companies. Therefore, this test gives a quite extensive set of examples and comparisons of the most important registration strategies today. The empirical results indicated that the relative orientation of airborne laser scanning data and aerial images is a feasible method in order to get data sets within the common coordinate frame. The experiment revealed that, currently, the level of automation was not the most significant factor affecting the quality of registration. More important factors included the type of tie features and the implementation of the methods. The processing time was shortest with most automatic methods, whereas the amount of manual work tended to increase the processing times. It should be noted that many of the methods were still at the developmental stage. It is expected that the performance and processing speed, in most cases. can be enhanced in the future. The test data represented an urban area and many of the methods relied upon certain objects, such as buildings. Therefore, the preformance of applied methods in non-built environments should be investigated separately.