Dune and alternate bar detection in a laboratory flume using a 3D laser scanner

Collecting high-precision data of migrating bed forms in flume experiments is often limited by the measurement equipment. With a 3D laser scanner a relatively large area of bed profiling can be monitored with high precision during the experiment. In the present study, the accuracy of such device is studied, applying corrections for internal calibration, path length and refraction. The total measurement error increases with increasing water depth and for water depths larger than 135 mm a filter should be applied to recognize a bed profile. For a sandy bed, application of a LOESS filter with different span widths leads to promising results for both dune and alternate bar patterns.