Lidar elevations

[Candace66]

Lidar itself does not give accurate data on elevation right off the bat. In fact it can vary noticeably from known, established benchmarks because of the resolution of the reflection points and the aerial-acquisition method has inherent noise. Your elevation model is only as good as your ground-control points and your calibration/calculation of the data.

At the USGS link I posted earlier, Lidar is described as "...a technology used to create high-resolution models of ground elevation with a vertical accuracy of 10 centimeters."

I haven't attempted to understand step-by-step how John Kirk, BD Loftin, and others are processing and analyzing. They've explained their methods in the 14ers.com threads I posted.  They're confident of their findings.  And the elevations, rises, and lists on the peakbagging sites will be updated with their results.

With regard to "known, established benchmarks", they were subject to surveying and mapping errors. Not to mention, vertical datums changing over the years.  Or, maybe I misunderstood what you meant by benchmarks?

There are some notable errors on the USGS topo maps where one or more contour lines are missing.  A great example is the Coxcomb Mountains range in California. There are three high points in close proximity.  And the 7.5' map shows the lowest of them as being the highest!  

Coxcombs brief analysis 

My Coxcombs trip report with map