Last month I decided to try to create a document that went over the nuances of tree height measurement using a laser rangefinder/clinometer system. I tried to include every detail that I thought people trying to learn the technique on their own might want to know. This is my current attempt at the proposition.
The full document with illustrations is 29 pages in length and can be downloaded as a pdf file below.The Really, Really Basics of Laser Rangefinder/Clinometer Tree Height Measurements
By Edward Frank – January 12, 2010
Many of us have been measuring tree heights for a long time. We have subconsciously incorporated
subtle details of the process into our routine. We have filed away much of what we have learned as
obvious. There are steps we go through without even thinking about the mechanics of what we are
doing. On the surface of everything, the process seems simple and it is if you know what you are doing.
Essentially we measure the straight-line distance to the top of a tree using a laser rangefinder. Then we
measure the angle to the top of the tree with a clinometer. The height above eye level is calculated
using a pocket calculator to be the trigonometric sine of the clinometer reading x the distance measured
to the top of the tree. The same process is used to measure how far the base of the tree extends
vertically above or below eye level. Then the number for the height of the base of the tree above or
below eye level is added or subtracted from the number for the top of the tree to get the total height of
the tree. If we able to show someone in person how to measure a tree, we can do a fairly adequate job
of it. But for people just learning the techniques on their own, it isn’t as straight forward and trying to
explain the process through emails, through online chats, or even through an article is a much more hit
or miss proposition. This is not only because of the math involved, but because of the variability in the
shapes of the trees and the obstacles to seeing their tops and base from a common vantage point.
Actual field situations add levels of complexity to tree measuring beyond that of the theoretical models
taught in forestry courses.