Lidar elevations

[GowerGulch42]

...airborne LiDAR data has several feet of uncertainty in sharp/rocky areas due to the unknowable effects of the laser footprint on each point's reported Z coordinate. Highly technical aspects of LiDAR data (like the point density and the laser footprint) can make or break a peak's ranked status in some cases...

The best way to improve this issue is by accessing the point cloud - the actual 3D web of laser reflections and manually selecting individual points which reflect true topographic features. In areas bare of vegetation this can be pretty good, and knowing what year the lidar was flown (the actual lidar unit might be in the metadata) can allow you to estimate the ground resolution, often between a square meter and a square foot in bare ground. 

Of course, to really get super good data you need a total station or other kind of differential GPS with cm - mm of accuracy. There's a new Geoid model coming out later this year so it will be important to re-calculate elevations across the country once that model is complete.