Eckert lll Projection
Central Meridian: Straight line half as long as the Equator.
Other Meridians: Equally spaced semiellipses concave toward the central meridian. The outer meridians, 180º east and west of the central meridian, are semicircles.
Parallels: Equally spaced straight parallel lines, perpendicular to the central meridian.
Poles: Lines half as long as the Equator.
Symmetry: About the central meridian or the Equator.
Scale is true along the 35º58' parallels and is constant along any parallel and between any pair of parallels equidistant from the Equator. No point is free of all scale distortion, but the Equator is free of angular distortion. This projection is not equal-area, conformal, or equidistant.
For this projection, only one standard parallel is specified. The other standard parallel is the same latitude with the opposite sign. The standard parallel is by definition fixed at 35º58'.
This projection was presented by Max Eckert in 1906.
This implementation of the Eckert III projection is applicable only for coordinates that are referenced to a sphere. If you want to project coordinates that are referenced to an ellipsoid, using the
projinvfunctions, then create a
projcrsobject instead of a map projection structure. You can create a
projcrsobject for the Eckert III projection using the ESRI authority code 54013. For example:
landareas = shaperead('landareas.shp','UseGeoCoords',true); axesm ('eckert3', 'Frame', 'on', 'Grid', 'on'); geoshow(landareas,'FaceColor',[1 1 .5],'EdgeColor',[.6 .6 .6]); tissot;