Cartography Flashcards
Equirectangular is also known as?
Equidistant cylindrical
or rectangular
What type of map is an equirectangular?
Cylindrical
Who invented the equirectangular projection? When?
Marinus of Tyre, CE 100 (some say 120)
What is a conformal map projection?
A projection in which any angle on Earth
is preserved in the image of the projection.
Describe the equirectangular projection
The projection maps meridians to vertical straight lines of constant spacing (for meridional intervals of constant spacing), and circles of latitude to horizontal straight lines of constant spacing (for constant intervals of parallels).
What does it mean to say a projection is equidistant?
The projection maintains scale along one or more lines, or from one or two points to all other points on the map.
Describe how the equirectangular projection’s condition is equidistant.
It is equidistant along all lines of latitude and longitude.
What is Tissot’s indicatrix
(Tissot indicatrix, Tissot’s ellipse, Tissot ellipse, ellipse of distortion)
A mathematical contrivance presented by French mathematician Nicolas Auguste Tissot in 1859 and 1871 in order to characterize local distortions due to map projection.
Who invented the Cassini (Cassini-Soldner or simply Soldner) projection, and when?
Described by César-François Cassini de Thury in 1745.
Describe the Cassini projection
It is the transverse aspect of the equirectangular projection, in that the globe is first rotated so the central meridian becomes the “equator”, and then the normal equirectangular projection is applied.
Describe Cassini distortions
Areas along the central meridian, and at right angles to it, are not distorted. Elsewhere, the distortion is largely in a north-south direction, and varies by the square of the distance from the central meridian. As such, the greater the longitudinal extent of the area, the worse the distortion becomes.
What type of projection is the Cassini?
Cylindrical
Describe the equidistant nature of the Cassini projection.
Distances along central meridian are conserved.
Distances perpendicular to central meridian are preserved.
Who invented the Mercator projection, and when?
Flemish geographer and cartographer Gerardus Mercator in 1569.
What is a line of constant course?
Known as rhumb lines or loxodromes, these are straight segments that conserve the angles with the meridians.
Is the Mercator projection cylindrical?
Yes
Is the Mercator map projection conformal?
Yes: The linear scale is equal in all directions around any point, thus preserving the angles and the shapes of small objects.
Describe Mercator map distortion.
The Mercator projection distorts the size of objects as the latitude increases from the Equator to the poles, where the scale becomes infinite. So, for example, landmasses such as Greenland and Antarctica appear much larger than they actually are relative to land masses near the equator, such as Central Africa.
Who made the Web Mercator and when?
A variant of the Mercator projection and the de facto standard for Web mapping applications. It rose to prominence when Google Maps adopted it in 2005.
How is a Web Mercator different from a Mercator map projection? What distortion does this cause?
Web Mercator uses the spherical formulas of the Mercator projection at all scales whereas large-scale Mercator maps normally use the ellipsoidal form of the projection. The discrepancy is imperceptible at the global scale but causes maps of local areas to deviate slightly from true ellipsoidal Mercator maps at the same scale. This deviation becomes more pronounced further from the equator, and can reach as much as 35 km on the ground.
Is the Web Mercator projection conformal?
The Web Mercator is not quite conformal due to its use of ellipsoidal datum geographical coordinates against a spherical projection. Rhumb lines are not straight lines.
Why do Google and other online map services use Web Mercator?
The benefit of the Web Mercator is that the spherical form is much simpler to calculate, saving many computing cycles.
Who made the Transverse Mercator map projection, and when?
The ellipsoidal form of the transverse Mercator projection was developed by Carl Friedrich Gauss in 1825 and further analysed by Johann Heinrich Louis Krüger in 1912.
Also known as Gauss–Krüger, Gauss conformal
Transverse Mercator
Who invented the sinusoidal projection and when?
Jean Cossin of Dieppe was one of the first mapmakers to use the sinusoidal, appearing in a world map of 1570
The sinusoidal projection is a _________ projection.
pseudocylindrical equal-area map
The sinusoidal projection is also known as _________
Sanson–Flamsteed or the Mercator equal-area projection
Describe the Sinusoidal projection’s Equal-area, Equidistant nature and how this creates the map’s shape.
Scale is constant along the central meridian, and east–west scale is constant throughout the map. Therefore, the length of each parallel on the map is proportional to the cosine of the latitude, as it is on the globe. This makes the left and right bounding meridians of the map into half of a sine wave, each mirroring the other. Each meridian is half of a sine wave with only the amplitude differing, giving the projection its name. Each is shown on the map as longer than the central meridian, whereas on the globe all are the same length.
Who invented the Mollweide Projection, and when?
The projection was first published by mathematician and astronomer Karl Brandan Mollweide of Leipzig in 1805. It was reinvented and popularized in 1857 by Jacques Babinet, who gave it the name homalographic projection.
What type of projection is the Mollweide projection?
equal-area, pseudocylindrical
The projection trades accuracy of angle and shape for accuracy of proportions in area, and as such is used where that property is needed, such as maps depicting global distributions.
What are the properties of a Mollweide projection?
The equator is represented as a straight horizontal line perpendicular to a central meridian one-half its length. The other parallels compress near the poles, while the other meridians are equally spaced at the equator.
The meridians at 90 degrees east and west form a perfect circle, and the whole earth is depicted in a proportional 2:1 ellipse.
Describe the type of map that the Goode homolosine projection is.
The Goode homolosine projection (or interrupted Goode homolosine projection) is a pseudocylindrical, equal-area, composite map projection used for world maps
Who invented the Goode homosine projection, and when?
The projection was developed in 1923 by John Paul Goode as an evolution to his 1916 experiments in interrupting the Mollweide projection.
Who invented the American Polyconic projection, and when?
The American polyconic projection was probably invented by Ferdinand Rudolph Hassler around 1825.
What class of projections does the American Polyconic projection belong to?
Polyconic projection class
Who invented the Bottomley projection, why’d they do it, and when did they do it?
It was introduced by Henry Bottomley as an alternative to the Bonne projection to reduce the extent of extreme distortion at the edges and give a more satisfying overall shape. 2003
Who invented the Bonne Projection, and when?
Although named after Rigobert Bonne, the projection was in use prior to his birth, in 1511 by Sylvano, Honter in 1561, De l’Isle before 1700 and Coronelli in 1696. Both Sylvano and Honter’s usages were approximate, however, and it is not clear they intended to be the same projection.
What type of projection is the Bonne Projection?
The Bonne projection is a pseudoconical equal-area map projection
Describe Bonne distortion
Parallels of latitude are concentric circular arcs, and the scale is true along these arcs. On the central meridian and the standard latitude shapes are not distorted.
Who invented the Werner projection, and when?
It is sometimes called Stab-Werner in reference to two originators: Johannes Werner, a parish priest in Nuremberg, refined and promoted this projection that had been developed earlier by Johannes Stabius of Vienna around 1500.
How is the Werner projection related to the Bonne projection?
The Werner projection is a limiting form of the Bonne projection, having its standard parallel at one of the poles (90°N/S). Distances along each parallel and along the central meridian are correct, as are all distances from the north pole.
Who invented the Albers projection, and when?
Heinrich C. Albers, 1805
Describe the Albers projection’s distortion
Although scale and shape are not preserved, distortion is minimal between the standard parallels.
