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Spectra Precision Survey Pro v4.6 Recon and Nomad User Manual User Manual

Page 248

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User’s Manual – GPS Mode

238

E

lli

ps

oi

d

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

Universal Transverse Mercator Projection

The scale factor at the central meridian (CM) is 0.9996. The scale

factor is 1.0 approximately 170-km east and west of the CM. The

scale factor is less than one between the CM and the point of
tangency. The scale factor is greater than one beyond the point of

tangency. Therefore, at the central meridian, a geodetic distance of

100m scales into a mapping plane distance of 99.96m.

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

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.

Fig. 3: Transverse Mercator Mapping Plane

A side view of the cylinder shows the effect of scale

distortion.