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Spectra Precision Survey Pro v4.5 Ranger User Manual User Manual

Page 215

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GPS Overview

205

Fig. 3: Transverse Mercator Mapping Plane

A side view of the cylinder shows the effect of scale

distortion.

E

ll

ip

so

id

Mapping Plane

K=0.9996

K=1.0

K=1.0

Central Meridian

K>1.0

K>1.0

K<1.0

Distance on Ellipsoid

Distance on Map



Ellipsoid

Terrain

h

Mapping
Plane








TDS Localization Stereographic Projection

The scale factor at the start location (usually the first GPS base
station in a project) is calculated for ground distances at the base

height. The scale factor increases more or less uniformly in all

directions as you move away from the base. The scale factor does not
change appreciable within the range of RTK GPS, so this map

projection is an excellent way to model simple flat earth ground level
coordinate systems.

Fig. 4: Localization Stereographic Mapping Plane

A side view of the ellipsoid and stereographic mapping

plane show the scale calculated for ground distances at

the base height.