Trigonometric Principles of tree Height Measurement
http://www.forestrynepal.org/notes/mensuration/tree/height/principles/trigonometric
Tangent Law
The height of the tree is calculated with the help of the tangents of the angles to the top and base of the tree and the distance of the observer from the tree.
My response:
I don't mind you using our diagram http://www.nativetreesociety.org/ in your tree measurement explanation http://www.forestrynepal.org/images/images/tangent2.jpg
- nepal.JPG (30.08 KiB) Viewed 214 times
but you are misrepresenting what it says. It says the sin(BAC) x distance (AB) as measured by a laser rangefinder is height BC, the sin(DAE) x distance (AE) is equal to height (DE). Total height is BC + DE. It is explicitly not FD + DE as you explain. The diagram shows the flaws within the tangent methodology. I would refer you to our measuring guidelines: http://www.nativetreesociety.org/measur ... vised1.pdf and here: http://www.nativetreesociety.org/measur ... sic_3a.pdf There are useful diagrams here: http://www.nativetreesociety.org/measur ... asure.html I would be happy to work with you to revise your web document and develop a better tree measurement methodology for your agency.
The original diagram is from a PowerPoint Presentation on our website, and as a heading illustration on the measurement page in the past.
Edward Frank
