Which projection is described as modified equal-area and not conformal nor equal-area?

Which projection is described as modified equal-area and not conformal nor equal-area?

• A. Lambert Conformal Projection
• B. Polyconic Projection
• C. Gnomonic Projection
• D. Stereographic Projection

Answer: (B)

Focus on how a projection treats shapes and areas. A projection described as not preserving angles is not conformal, and one that does not preserve area is not equal-area. The polyconic projection sits between these two extremes: it is neither conformal nor equal-area. Some sources describe it as a “modified equal-area” approach because it tries to balance distortions in a way that mid-latitude regions look reasonable without maintaining true conformality or true area preservation. In practice, scale and shapes vary across the map, and neither angle nor area is preserved exactly. The other projections here have clearer, specific properties: Lambert conformal conic is conformal (preserves shapes locally), gnomonic is a perspective projection with its own distortion characteristics (not equal-area or conformal), and stereographic is conformal. So the projection that best fits the description of being not conformal nor equal-area (and sometimes labeled as modified equal-area) is the polyconic projection.

Focus on how a projection treats shapes and areas. A projection described as not preserving angles is not conformal, and one that does not preserve area is not equal-area. The polyconic projection sits between these two extremes: it is neither conformal nor equal-area. Some sources describe it as a “modified equal-area” approach because it tries to balance distortions in a way that mid-latitude regions look reasonable without maintaining true conformality or true area preservation. In practice, scale and shapes vary across the map, and neither angle nor area is preserved exactly.

The other projections here have clearer, specific properties: Lambert conformal conic is conformal (preserves shapes locally), gnomonic is a perspective projection with its own distortion characteristics (not equal-area or conformal), and stereographic is conformal. So the projection that best fits the description of being not conformal nor equal-area (and sometimes labeled as modified equal-area) is the polyconic projection.