Learn & Learning

Use Spiegel Relaskop basically want a relatively flat field. Dimensional measurements of trees in forest plantations can still be said to not invite constraint. However, in the wilds often face obstacles. Generally relatively high levels of density with irregular distribution, let alone be in the land that is undulating or hilly. Constraints referred to is when measuring the diameter of a rod with a sloping land surface.
The formula used for determining the diameter is


This formula applies only to the position of measurement in the land is relatively flat (flat distance measurement). When the angle formed between the measuring against a tree trunk at 10% or more, then the formula needs to be an adjustment (Simon, 1996).
Form of adjustment (correction angle) formulation uses cosine with the scale upright (vertical) on Spiegel Relaskop (degree scale ranging –90° s/d +90° or scale percent –150% s/d +150%) magnitude and angle similarity 45° = 100%.


When the value of φ = α°, then Jd = Jm cos (α°)
When the value of φ = p%, then Jd = Jm cos (0.45 p)

So that the magnitude of the adjustment calculation formula diameter:

D (cm) = [{(nF x 4) + nQ}/2] . Jm . cos(α°)
D (cm) = [{(nF x 4) + nQ}/2] . Jm . cos(0,45 p)

A simple example:
1. The result of reading the bar at the crack of view gained 3 full bars and at 1.5 to 1/4 bar. Shot as far as 12 meters at an angle viewfinder 4°03’00”.

2. The result of reading the bar at the crack of view gained 3 full bars and at 3.5 to 1/4 bar. Shot as far as 12 meters with a 11% angle viewfinder.

A2Karim
*) findings & frame of mind. 080601
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