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?