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Compass traverse

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Compass traverse The compass traverse is commonly used in forestry http://www.cfr.msstate.edu/studentorgs/saf/conclave/RULES/compass.htm One of the greatest ... – PowerPoint PPT presentation

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Title: Compass traverse


1
Compass traverse
  • The compass traverse is commonly used in forestry
  • http//www.cfr.msstate.edu/studentorgs/saf/conclav
    e/RULES/compass.htm
  • One of the greatest expeditions of exploration in
    history used compass traverses as their primary
    mapping tools.
  • http//www.edgate.com/lewisandclark/mapping_on_tra
    il.html

2
The Forks of the Missouri sketched by Capt. Wm.
Clark.. Note the grid base, the transect data
and the features sketched along the river
(bluffs, meanders, islands etc.)
3
A portion of the field notes for a daily compass
traverse recorded by Capt. Wm. Clark
4
The Compass provides accurate measurement of
angles.
5
Orienteering compass
6
Orienteering as a sport.
http//www.orienteering.org/ http//www.us.oriente
ering.org/ http//www.williams.edu/Biology/oriente
ering/oindex.html http//www.learn-orienteering.o
rg/ Using the map and compass to wander around
in the backside of the world!
7
A compass does not always point north!
The degree to which a compass points a direction
OTHER than north is called magnetic declination
8
In order to make accurate maps using a compass it
is essential to understand how the compass can be
deceived, and the natural distortions inherent in
the earths magnetic field.
Lines of equal magnetic declination are called
agonic lines..Note the magnetic declination lines
in North Alabama are very close to 0
9
measuring distance with the human body
The pace is the standard measure used by field
workers it can be a highly accurate tool for
distance measurements.
10
OTHER TOOLS FOR MEASURING DISTANCE
  • The survey chain, 33 or 66 feet long, forged
    iron (fair dimensional stability) THE tool for
    original survey work.  

11
Tape
  • Tape measures, made possible by the development
    of new materials, mylar or steel strips. Tapes
    are accurate, and awkward.
  •  

12
Measuring wheel
  • Measuring wheel, accurate and can be used by a
    one man crew. Mechanical counters have been
    replaced by electronic counters. Fairly common.

13
Parallax range finder
  • Parallax range finder uses the principle of
    parallax to estimate distance based on the path
    of light from an object. Camera range finders
    work on this principle.

14
Laser Range finder
  •  the big time. Highly accurate, no problems with
    dimensional stability, the basis for modern
    survey practice! Send a laser pulse to a target
    and measures the time required to for the
    reflection to return to the observer.

15
The laser total station
16
  • The laser total station combines a laser based
    distance measuring device with a highly accurate
    device to measure angles (vertical and
    horizontal)
  • The total station can convert all field
    observations into a data file which can be
    downloaded directly into a computer mapping
    application.
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