Modern mapping technologies used for coastal studies such as LIDAR and RTK?GPSrnproduce massive amounts of data characterized by oversampling and noise. The physicalrnphenomena and landscape changes examined are often subtle and besides statistical accuracy,rnadequate representation of surface geometry is crucial for correct interpretation of measuredrndata. We have explored the suitability of the Open source GRASS GIS and its spline basedrnspatial interpolation for assessment of rapid changes in topography of nourished beach on BaldrnHead Island, NC based on the LIDAR 1997?2000 and RTK?GPS 2001?2002 data. Surfacerngradient and curvatures, needed for topographic analysis were computed simultaneously withrninterpolation. Raster map algebra was used for data management (masking, extraction ofrnsubsets) as well as for spatio?temporal analysis, such as computation of first and second orderrndifferences between surfaces and volumes of lost sand. Visualization of multiple 3d surfacesrnwith moving cutting planes provided powerful tools for visual identification of features andrnbeach morphology changes.
展开▼
