aplanissement hydrologique

CONT: Hydro-flattening is the process of creating a lidar [light detection and ranging]-derived DEM [digital elevation model] in which water surfaces appear and behave as they would in traditional topographic DEMs created from photogrammetric digital terrain models (DTMs).
OBS: [A] digital elevation model (DEM) or triangulated irregular network (TIN) derived from LiDAR [light detection and ranging] data will show unpleasant and unnatural water surface due to the fact that LiDAR data does not provide natural breaklines and the elevations of water points is not uniform. Furthermore, hydrologic connectivity in water surfaces is necessary to ensure that the elevation of water surface decreases from upstream (U/S) to downstream (D/S). Therefore, the LiDAR data is hydro-flattened so that water bodies such as streams, rivers, and long reservoirs show an elevation change along their length, whereas ponds, lakes, or other cartographically polygonal water surfaces show a static water surface, consistent with their natural behavior and the surrounding topography ...