# Geography 2122A/B Chapter Notes -Developable Surface, Map Projection

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Published on 16 Apr 2013

Department

Geography

Course

Geography 2122A/B

Professor

Map Projection

- a map projection is a geometrical transformation of the

earth’s spherical or ellipsoidal surface onto a flat map surface

Map Projection Properties

- Scale

- Completeness

- Correspondence relation

- Continuity

Map Projection Properties: Scale

- Scale

o The stated scale is true only at selected points or along

particular lines

- There are two map scales:

o Principal scale: the scale of generating globe (no

variation)

o Actual Scale: the scale we measure at any point on the

map. Scale variations here is the result of geometric

distortion

o SF = Actual Scale / Principal scale

Map Projections Classification Categories

- Projectin families based on map projection surface

o Projection surface

o Developble Surface: the flat surface that the earths

features are projected onto

o Three projections families based on the developable

surface:

Planar

Conic

Cylindrical

## Document Summary

A map projection is a geometrical transformation of the earth"s spherical or ellipsoidal surface onto a flat map surface. Scale: the stated scale is true only at selected points or along particular lines. There are two map scales: principal scale: the scale of generating globe (no variation, actual scale: the scale we measure at any point on the map. Scale variations here is the result of geometric distortion: sf = actual scale / principal scale. Projectin families based on map projection surface: projection surface, developble surface: the flat surface that the earths features are projected onto, three projections families based on the developable surface: