Lab 5 - Projections

The first equal area projection that I have presented is the world-cylindrical projection. This is a map projection in which the surface of the globe is depicted as if projected onto a cylinder. A cylindrical projection produces a rectangular map with the equator in the middle and the poles at the top and the bottom. Distortion of the shape and scale is minimal near the equator and is maximal near the poles. The distance between Washington D. C. and Kabul, Afghanistan on this projection is 10200 miles.

         My second equal area projection is Bonnie projection. It is named after Rigobert Bonnie after he used it extensively in his 1752 maritime atlas. It is a pseudo-conic projection; the parallels are plotted as concentric, equally spaced arcs. This projection was very popular in the first half of the 20^th century, but it lost its popularity in the recent years, because the distortion around the edges limits its use in global maps. The distance between Washington D. C. and Kabul, Afghanistan on this projection is 6590 miles.

          My first equidistant projection is the equidistant-cylindrical projection. This is a fairly simple projection that maps meridians to vertical straight lines and circles of latitude to straight lines that are spread evenly. Equidistant-cylindrical projection has very little use in navigation or cadastral mapping. It is mainly used in thematic mapping and has become standard for computer applications because of its very simple relationship between the positions of the image pixels on the map and its corresponding location on Earth. The distance between Washington D. C. and Kabul, Afghanistan on this projection is 5066 miles.
          The second equidistant projection is the equidistant-conic projection. This projection is very simple to construct and are widely used in regional and national maps of temperate zones. However this projection is not so appropriate for world maps. The equidistant-conic projection has constant parallel spacement, so the scale is the same along all the meridians. The distance between Washington D. C. and Kabul, Afghanistan on this projection is 6950 miles.

          The first conformal projection presented here is the World-Mercator projection. On this map all the lines on constant bearing (rhumb lines) that make constant angles with meridians are represented by straight segments. This projection is widely used for navigational purposes at sea. Its 2 properties – conformality and straight rhumb lines make this projection uniquely suited to marine navigation. The distance between Washington D. C. and Kabul, Afghanistan on this projection is 10200 miles.
          The second conformal projection is the World-Gall-Stereographic projection. This projection is an improvement upon the Mercator projection. The northern and southern parts of the map are stretched horizontally; while the whole map is stretched vertically. World-Gall-Stereographic projection is mostly suitable to show the temperate countries. The distance between Washington D. C. and Kabul, Afghanistan on this projection is 7268 miles.

          As we can see from all these types of projections the shape and scale of the countries, the distance between two locations on Earth is widely dependent on the projection that has been used. This is shown by our lab work – the distance between Washington D. C. and Kabul, Afghanistan ranges between 5066 to 10200 miles on different projections, while the true distance is 7000 miles.