Pseudocylindrical map projections have in common straight parallel lines of latitude and curved meridians. Until the 19th century, the only pseudocylindrical projection with important properties was the sinusoidal or the Sanson-Flamsteed projection. The sinusoidal has equally spaced parallels of latitude, true scale along parallels, and equivalency or equal-area. As a world map, it has the disadvantage of high shear at latitudes near the poles, especially those farthest from the central meridian.
In 1805, Karl Brandan Mollweide (1774–1825) announced an equal-area world map projection, aesthetically more pleasing than the sinusoidal, because the world is placed in an ellipse with axes in a 2:1 ratio and all the meridians are equally spaced semiellipses. The Mollweide projection was the only new pseudocylindrical projection of the nineteenth century to receive much more than academic interest.
The lecture will start with a brief description of Mollweide's life and work. The formula or equation in mathematics named after him as Mollweide's formula will be shown, as well as its proof "without words". Then, the Mollweide map projection will be defined and formulas derived in different ways to show several possibilities leading to the same result. The inverse equations will be derived as well.
The most important part in research of any map projection is the distortion distribution. That means that the talk has to continue with the derivation of formulas enabling us to gain insight about the linear and angular distortion of the Mollweide projection.
Finally, the ICA logo will be used as an example of a good application of the Mollweide projection. The talk will finish with a comparison of some similar map projections. The map painted on the ICA flag is going to be mentioned. It seems the map was not produced according to the Mollweide projection and is different from the ICA logo map.
Friday, October 21 2011, 11 amSeminar room 126Research Group CartographyErzherzog-Johann-Platz 1, 1040 Wien