Is there any way to extract a river boundary (bank) from LiDAR data and its products (DEM, intensity image and slope) automatically? Digitizing is very time consuming.
I've been in LiDAR processing for a couple of years now. The best approach we've found is to classify the suspect water points to something other than ground. Should be easy just classifying based on intensity (near nadir points will have high intensity, whereas turbid water will be close to 0) and laser shots are usually absorbed near shore anyway. However, there is still some interpretation and manual modification required
After water points are classified to non-ground, export a ground-only DEM representing intensity. The data voids in the DEM will have 0 values, representing probable water bodies. With some tinkering (i'm not giving away all of my secrets) in model builder, you can convert the raster to polygon, apply some smoothing, and voila...semi-automatic extracted breaklines.
Be warned that this still takes time and a careful eye to do it properly. Nothing is as accurate as the human eye. Good luck. Results may vary.