Plane Table Mapping

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Plane Table Mapping

• The power of triangles
• And
• Appropriate Technology

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Any object can be located using triangular rays.
Virtually unchanged through history except most
of the guys now doing the horizontal measurements
use a tape measure and wear pants (and dont have
wings)
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Plane Table Mapping

• Simple Equipment a flat surface with paper
  attached
• An Alidade (a straight line sighting device)
• A pencil
• this puts very accurate mapping in the hands of
  anyone

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17th century onward.

• tool uses intersection of lines to locate points
  that are plotted on the paper on the table.
• Elevation is not considered in most plane table
  maps only horizontal locations of objects on the
  landscape.

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The process

• Establish a baseline (the baseline needs to be
  scaled to the project and features that are to be
  mapped need to be visible from the baseline.
• Multiple baselines can be used as necessary but
  the second baseline must be correctly tied to the
  initial baseline.
• The baseline can be extended to points plotted
  off the initial baseline. Extremely large areas
  can be mapped with a fair degree of accuracy
  using this method

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Process contd.

• The plane table is set up over the initial point
  on the baseline.
• Layout your paper so that it will easily contain
  the boundaries of the objects you are trying to
  map.
• You will need to calculate the scale 11meter?
  The scale will determine how much shows up on
  your completed map. The scale needs to be
  appropriate to the project!
• Use the Alidade (in our case triangular scale) to
  sight to the opposite end of the baseline.
• Draw in the baseline.

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• If you can see it you can map it.
• Sight across the plane table at features that
  will be located on your map. One end of the
  Alidade will be on the initial point of the
  baseline, the other end will be exactly on the
  correct point, because light rays travel in
  straight lines. And your eyes are highly
  accurate.
• MAKE SURE YOU ARE USING THE SAME EDGE OF THE
  RULER (Alidade) each time!

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Your initial map

• You are not mapping objects yet.
• You are locating the points in space where
  objects are!
• You initial map will consist of nothing more than
  straight pencil lines (drawn in nice and light)
  with notes as to what sort of object you are
  locating
• MAPPING is done by adding information to you
  locations. Cartographic symbolism.

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So why use the plane table?

• Unfortunately-or fortunately-the total station
  with data collection made the plane table and
  alidade into museum pieces
• Is the plane table simply a museum piece?
• What can we learn from using these tools?
• Are there applications for this technology?