Midterm Theory Flashcards
1
Q
Map Projection
A
- Systematic rendering of a graticule onto a flat sheet
2
Q
Three Projection Surfaces
A
- Flat plain: Tangent at the pole
- Cylinder: Tangent along equator
- Cone: Tangent along a parallel with apex over a pole
3
Q
Orthographic Position
A
- Outside the globe at infinity
4
Q
Stereographic Position
A
- Outside the globe, opposite the point of contact/tangency
5
Q
Gnomonic Position
A
- Light source for projection in centre of globe
6
Q
Transverse Projection
A
- 90 degree change of projection surface
7
Q
Transverse Cylindrical
A
- Tangency along a meridian
8
Q
Transverse Plane
A
- Tangency at equator
9
Q
Transverse Conical
A
- (Rare) Apex at equator
10
Q
Oblique Projection
A
- Angle between 0 and 90 degrees
11
Q
Standard Line Projection
A
- Line of tangency between projection surface and globe surface
- No distortion (one to one relationship)
- Away from the line, distortion varies
12
Q
Secant Projection
A
- Result for cylinder and cone (two or more standard lines)
- Result for tangent plane, distortion except at the tangent point
- Result for intersecting plane: small circle formed along the interception (standard line of projection)
13
Q
Two major Characteristics (Projections)
A
- Conformality: Retention of correct angles, map features have distinct shapes, long. and lat. meet each other at right angles, consistent scale.
- Equivalence: Areas represented with the same number of square units on the map as on the globe/earth, Maps with this characteristic are equal-area maps
14
Q
Minor Characteristic (projections)
A
- Distance: Length of straight line between two points represent correct great-circle distance
15
Q
Tissot’s Indicatrix
A
- Characterizes local map distortions due to map projections, Stretched wider at the poles.
