Week 8, Lecture 1: Map Projections
Patterns of Deformation
Distortion is least at the contact between the projection surface and the surface of the globe,
and increases away from the point or line of contact.
Three kinds of distortion: Tearing, Compression, and Shearing
Projection Families and Patterns of Deformation
Azimuthal used commonly when projecting the poles, used often in Canada’s North
Mercator= Cylindrical Projection Conical Surface, projection is not full world view. Easy to recognize due to the grid pattern (azimuthal is
plain and circular while conic captures a ‘face’)
Tissot’s Indicatrix,used for various types of maps, conformal (cylindrical Mercator projection),
equal-area (azimuthal), and equidistant (cylindrical PLATE CARREE)
Classes of Map Projections Based on Geometric Properties
Four important classes of map projections based on their geometric properties:
2. Equivalent/ equal area
**Compromise is the acceptance of distortion, as long as it is minimized!
Conformal projections preserve the property of angular relationships, or local shape so that the outline
of a small area is correct.
Angles meet at right angles
Used for measuring direction, and navigation
scale is true at the equator (least amount of distortion)
’squares’ grow larger when traveling North or South of the equator
Conformal Projections preserve direction around any one given point!
Conformal Projection= Mercator Map
Lambert Conformal Conic: area and shape are distorted away from standard parallels, used for North
America maps (Lambert Conformal Conic) Equivalent, Equal Area
Equivalent or equal area projections preserve area, all parts of Earth’s surface are shown with their
correct area, as on the sphere.
**Note: Conformity (shape) and equivalence (area) properties are mutually exclusive. YOU
CAN’T HAVE BOTH!
Albers Equal-Area Conic: conic p