ee plane table mapping
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Plane Table Mapping
The power of trianglesAnd
Appropriate Technology
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Any object can be located
using triangular rays.
Virtually unchanged
through history
except most of theguys 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 tobe scaled to the project and features that areto be mapped need to be visible from the
baseline.Multiple baselines can be used asnecessary but the second baseline must becorrectly tied to the initial baseline.
The baseline can be extended to pointsplotted off the initial baseline. Extremelylarge areas can be mapped with a fair degreeof accuracy using this method
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Process contd.
The plane table is set up over the initial point on thebaseline.
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 1=1meter?The scale will determine how much shows up on yourcompleted map. The scale needs to be appropriate tothe project!
Use the Alidade (in our case triangular scale) to sightto 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 theAlidade will be on the initial point of thebaseline, the other end will be exactly on thecorrect point, because light rays travel instraight lines. And your eyes are highlyaccurate.
MAKE SURE YOU ARE USING THE SAMEEDGE 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 morethan straight pencil lines (drawn in nice andlight) with notes as to what sort of object you
are locatingMAPPING is done by adding information toyou 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 piecesIs the plane table simply a museum piece?
What can we learn from using these tools?
Are there applications for this technology?