Stick bearing

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The stick bearing is a method to estimate the height of a relatively close object . It is mainly carried out by forest workers and foresters to determine the size of trees .

background

Principle of determining the height of a tree using a stick, as carried out by tree workers

Similar to the thumb jump, this estimate is based on the route relationships of the ray theorem. The aimed stick (measuring stick) on the outstretched arm of an adult is about 70 centimeters from the face. If the distance to the tree is known, the height of the tree can be read off the stick with relative accuracy. The thumb jump would not be suitable here, since this only allows a horizontal estimate.

execution

version 1

  • Determine the distance to the tree
  • A wooden stick of any size with measuring marks is held up on the outstretched arm.
  • The tree base is aimed at using the lowest bar marking.
  • The marking on the wooden stick above which the tree top can be sighted shows the height of the tree either directly or after multiplication with a factor.

Advantage: The scale on the stick can be divided so that the tree height can be read directly at a certain base distance. Bearing is possible from any distance if the measurement result is converted with a factor that results from the ratio of the actual bearing distance to the base distance for the scale.

Variant 2

Schematic representation of variant 2 / Förster triangle
  • The stick is held vertically in such a way that the upper end protrudes just as far beyond the hand as your own, horizontally outstretched arm is long. Then the arm and the upper stick section form the two equally long sides of an isosceles, right-angled triangle; the third side of the triangle (line of sight from the eye to the upper end of the stick) is then at an angle of 45 ° to the horizontal.
  • Now you go backwards from the tree to be measured until the upper section of the stick appears as long as the tree or as the vertical distance from your own eye level to its top.
  • The tree height minus your own eye level results from the distance from the determined position to the tree. For the full height of the tree, you have to add your own eye level to the distance mentioned.

Advantage: A scale division on the stick is not necessary. At the same time, the determined position automatically gives the minimum necessary safety distance when felling the tree.

Variation 3

  • Similar to variant 2, but the stick has two markings: One marker F at arm's length below the tip of the stick and another marker H at eye level above the shoulder joint (approx. 17 cm) below F.
  • The stick is grasped at marking H and held vertically on the outstretched arm and the tree foot is aimed at using marking F. The outstretched arm and the line of sight over F now ideally form a parallelogram.
  • Now you go backwards from the tree to be measured until the top of the tree can be aimed at via the top of the stick and at the same time via F the base of the tree.
  • The distance from the current position to the tree corresponds to the height of the tree.

Advantage: The measurement also works in steeply sloping terrain and for measurements of sections in the crown of the tree.

See also

Web links