GPH370 LAB 4: MAP PROJECTIONS

I. Visualizing Distortion

1. Meridians/parallels labeled on maps below:

2. See boxes on maps above. On both projections, the boxes have changed shape, “leaning” towards the 0 meridian on the Mollweide projection and becoming stretched on the outer side with curved edges on the Stereographic Equatorial projection. In the Mollweide projection, area has been maintained in spite of the “leaning” shapes of the boxes as this is an equal-area projection, while on the Stereographic Equatorial projection, area does not appear to be preserved. The Stereographic Equatorial Projection is a conformal azimuthal projection and all parallel and meridians intersect at right angles, while the Mollweide projection is not a conformal projection.

3. Land mass distortion on the Mollweide projection is minimal as this is an equal-area projection and both South America and Africa appear very similar as they are on the globe. The Stereographic Equatorial projection however has quite a lot of land mass distortion, as in this example where South America appears to be much larger than Africa.

II. Map Projections: Below find map projections created on Map Maker for cylindrical, conic and planar developable surfaces.

III. Matching the projection to the purpose.

1. The Mercator projections are the best to use for determining compass headings (such as a long-distance hiker with only a compass would use) and were traditionally often used for marine navigation.

2. The Albers equal-area conic projection would be a good choice for mapping distribution of population in the former Soviet Union, as areas are proportional and this projection is often used for mid-latitude large countries with larger east-west than north-south extent. See example from Map Maker below:

3. In order to determine distances to areas around North America from Chicago’s O’Hare airport, you can alter the North Polar Azimuthal projection so its center is on Chicago (as in the example below). By doing this distances calculated from the center (in this case Chicago) are true for local areas (though map properties are distorted the further from the center you travel.