The paper introduces in airborne laser scanner architecture and its data postprocessing. One main problem is the definition of a contiguously measured digital terrain model (DTM) by filtering neighboring strips and their attachment to each other. These problems are solved by spline approximations and datum transforms. The spline approximation starts with a bicubic polynomial which can be reparameterized in terms of its function values and the first derivatives as new unknown parameters. Filtering is carried out in a two dimensional rectangle bordered by the nodes of the spline. The next step of the data postprocessing is the datum transform. Using a similarity transform the seven datum parameters have to be defined by a data snooping procedure with non-parametric hypothesis tests. The reason for using non- standard test statistics is the systematic effects produced by the sensor system itself are man- made and natural 3-D phenomena cannot be eliminated a priori perfectly. Therefore, the datum transform should give the hints which observations are blunders and which are not.
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