Clinometer Calibration - John Eicholz Edward Frank Dec 15, 2005 18:25 PST

John, ENTS,

I have been looking over various posts on Instrument Calibration. This
one gives a nice mathematical summary of the theoretical errors in
height due to potential clinometer error. The point I want to make here
is that if as you wrote:

 I think I can prove mathematically that the error in tree height that results from each degree of clinometer error is approximately between 1.75% and 1.9% of the horizontal distance to the trunk...Because the factor: (1/cos(@))*(Sin(@)-sin(@+e)) is nearly a constant! Its range is a smooth progression from 1.74% at 0 degrees to 1.9% at 80 degrees.

Doesn't that mean that if you are taking clinometer readings of both the
base and the top, that the errors would subtract from each other? So
therefore maximum error would be 1.9% - 1.74% = 0.16% of the baseline
distance to the tree? (So long as it was off less than 1 degree or so)?
Therefore the actual error generated by a clinometer error would be more
in the range of 2 inches per 100 feet baseline rather than the 1.5 to 2
feet cited in the discussion?

Ed Frank

John Eicholz-