Version 2 (modified by stgo, 10 years ago) (diff)


Comparison of lidar dems

We patch lidar data on to ASTER data during delivery creation and need to know how accurately that data has been patched and, if it is differing, to what level it differs.

To do this we can use: -d lidarpatched.dem -n navfile.sol --lidar path/to/ascii -l projection

Unless you have an SSD available in your machine this will probably take a while.

This will create a patched aster dem to compare to the lidar dem, this will not be smoothed and as such is the raw ASTER data. It will give 2 outputs on completion the first is only the area covered by the lidar files, the second is the area only covered by the lidar data. All outputs are in metres.

Preferably the averages would be around 0 metres, but in practice it tends to be around 4 - 8 metres for UK data and varying for UTM data.

You can compare 2 dems already created using -d dem1.dem -c dem2.dem --lidar /if/needed

Which will skip the patching process and just give the dem outputs, if you use identical dems the outputs will be 0.

There are a few other options for deeper analysis of dems, and analysis of trends over years