I wants to extract built up area from LiDAR data can any one suggest me how to extract and work on the softwares(ArcMap, ERDAS and Lastools or any open source software) and ware i can fine free Lidar data sets of any city.
If you can work with high-resolution raster data, rather than LAS point clouds, then extracting built-up areas may be done by subtracting a DEM representing bare earth (or 'last return' or 'ground return') from a DSM representing the full point cloud prior to filtering (or 'first return' or 'highest hit'). This simple raster calculation can be done in ArcGIS, Matlab, or a number of other open-source software packages.