In the flight path reconstruction, the exact position of the LIDAR system is determined using a differential GPS computation from the data recorded in the aircraft and a ground reference station synchronously recording data. The altitude and orientation of the LIDAR system is established by an IMU (Inertial Measurement Unit). The result of this combination of data produces an exact reconstruction of the flight path.

The pre-processing (referred to in the flowchart below as "range to elevation & transformation") is finely matched to the characteristics of the TopoSys LIDAR system. It receives the laser distance measurements recorded during flight and the reconstructed flight path and computes the 3D coordinates of each laser pulse from them. The coordinates of point cloud configuration can be transformed into an independently defined coordinate system or into one of the over 50 national coordinate systems already in existence.

Post-Processing:

The post-processing provides import filters and tools for the further processing of the raw data. This begins with the conversion of the point clouds into raster data. It further comprises programs for filtering vegetation and objects and for changing the raster width. Here a digital elevation model adapted to the customer’s application can be calculated by selecting the suitable parameters. Data thinning programs (TIN) and converters for other formats also form part of the post-processing and are referred to as “DEM tools” in the flowchart.