Regular Measurements at two-week Intervals during one Year

To support a doctoral project with a focus on long-term observations, repeated measurement runs were carried out every two weeks between March 22, 2017 and March 20, 2018, i.e. over a whole calendar year, along a pre-planned route of about 20 km (through the districts of Nordstadt, Stöcken, Leinhausen and Herrenhausen in Hannover) using a Riegl mobile mapping system. Each measurement run lasted between 60 and 80 minutes. The result is a data set of 25 individual projects (point clouds, trajectories, camera images), which allows to superimpose point clouds from different epochs and to compare differences/changes.

For the evaluation of all projects, a uniform processing workflow was established for this purpose, in the result of which all point clouds were equalized/corrected among themselves in order to minimize errors in the trajectories of all trips. This drastically increased the absolute accuracy of the point cloud, which makes it possible to compare point clouds from different epochs.

The PhD project now deals, among other things, with the change analysis in a spatial grid, which allows a characterisation of the environment via the type/frequency of the detectable changes in the point cloud. This allows the detection and classification of temporally periodic processes, which not only allows a distinction between static and dynamic objects, but also a prediction of the occupancy state of the spatial cells.