I'm using a DTM retrieved from LiDAR data and I noticed that forested areas are grainy or not defined. The DTM data was retrieved from geostore.com. Here is one example:
Is there any way to directly improve the DTM file; or do we need the raw LiDAR data (las files) in order to rebuild the DTM and get better results?
Here is the same location viewed from a satellite image.
And here is an attempt of DTM made from a DSM in SAGA:
Note that I don't want to smooth the DTM as I do archaeological surveys and any smoothing of the surface would hide the barely visible features.