Map Projections and Distortion Questions and Answers

Answer: A

Correct answer: area

Albers is the equal-area conic, the counterpart to Lambert’s conformal conic on the same cone. Its two standard parallels make it well suited to a region wider than it is tall in mid-latitudes, which is why it is the standard choice for statistical maps of countries such as the United States, where comparing quantities by area is the point of the map.

Answer: B

Where the cone touches or cuts the globe, scale is correct; away from those lines it departs progressively. Two standard parallels give a secant cone, which holds the error lower across the whole mapped band than a single tangent line can.

Answer: C

Correct answer: a compromise projection

Robinson preserves nothing exactly. It was constructed by choosing parallel lengths and spacings by eye until the whole world looked acceptable, so shape, area, distance and direction are all slightly wrong and none is badly wrong. That makes it a good general-purpose world map and a poor one for measurement - a distinction worth keeping, since a compromise projection is not a failed equal-area projection.

Answer: D

It is an equal-area cylindrical projection, so the relative size of regions is correct and the exaggeration of high latitudes seen on Mercator disappears. Shapes are noticeably stretched in compensation, which is the trade equal-area always requires.

Answer: A

Cutting the map where there is little land keeps each lobe close to its own central meridian, so shapes stay reasonable while area is preserved. The cost is that the oceans are torn and continuous routes cannot be followed across them.

Answer: B

Projection is imagined as two steps: shrinking the Earth to a globe at the principal scale, then flattening that globe. Only the first step is uniform, so the actual scale on the sheet varies from place to place around the principal value.

Answer: C

A scale factor of one means the scale there matches the generating globe exactly. Values above or below one show where the projection has stretched or compressed, which is why the factor is quoted for standard lines and central meridians.

Answer: D

Correct answer: keep all values positive

A false easting is a constant added to the eastings so that no coordinate in the mapped area comes out negative - in UTM, 500,000 m is added to the central meridian. Negative coordinates invite sign errors in manual work and in software, so shifting the origin off to the west of the zone removes the problem entirely. A false northing does the same for the southern hemisphere.

Answer: A

The projection is arranged symmetrically about it, and distortion grows with distance east or west. On a secant zone such as UTM the scale along that meridian is deliberately slightly less than one rather than exactly one.

Answer: B

Any conclusion about relative size depends on areas being represented in true proportion, so an equal-area projection is required. Mercator is the classic wrong choice for this purpose, because its high-latitude exaggeration is severe.