I am working with LAS files , but the files do not have any classifications (they all appear as Code 8 Model Key/Reserved) or when the classifications appear they are all classified as Code 2 ground. I have tried to change the classification codes, but the heights are too similar that it will classify buildings as ground. I have tried changing the classification codes, building a DSM, DTM, nDSM, but I have no polygons to extrude the buildings.
What are different ways to make lidar point cloud data 3D?