Projections

Map Projection

A method of preprocessing the earth’s #D surfaces as a flat 2D surface

Facts (7)

1. are math based

2. scale is true only in certain places

3. many difference types

4. all maps distortion or have error

5. distortion vary from type

6. some types are better for diff stuff

7. a few are used widely

three types of projections

1. Cylindrical 

2. Conical (triangle)

3. Planar (circle)

Secant

cutting or touching multiple lines

Tangent

Being in contact with ONE SINGLE point

Where is scale only true

where the surface contacts the globe (Standard lines)

The 4 distortions

1. Shape

2. Area

3. Distance

4. Direction

   1. SADD

4 classes of distortion

1. Conformal

2. Equal Area/Equivalent

3. Equidistant

4. Azimuthal

Conformal

1. preserves shape and angles

2. area is distorted

   1. Mercator projection (Clyindrical)

3. large scale maps and coordinates

Equal Area/Equivalent

1. preserves area and size

2. angles and shapes are distorted

   1. Albers Conic

   2. Mollweide

   3. Cylindrical = project

3. small scare maps

Equidistant

preserves distance (scale) from only one or two points

• true distance for special 

Azimuthal

1. preserves all angles from a specific point

2. shapes and areas are distored

   1. true direction for special

Polyconic projection

NO properties are preserves but scale is true along all parallels, and distortions of all kinds are mini

Only correct rep of earth

Globe

Misregistered

When an error occurs to incorrectly align features/lines on maps

Registered

Properly georegistered and aligned

Scale

a ration that relates to the measurement on the map

Large Scale

• Map zoomed in + detail

• Small area

Small Scare

• Zoomed out

• large area

• less detail