Gall Isographic Projection
Meridians: Equally spaced straight parallel lines more than half as long as the Equator.
Parallels: Equally spaced straight parallel lines, perpendicular to and having wider spacing than the meridians.
Poles: Straight lines equal in length to the Equator.
Symmetry: About any meridian or the Equator.
This is a projection onto a cylinder secant at the 45º parallels. Distortion of both shape and area increase with distance from the standard parallels. Scale is true along all meridians (i.e., it is equidistant) and the two standard parallels, and is constant along any parallel and along the parallel of opposite sign.
For cylindrical projections, only one standard parallel is specified. The other standard parallel is the same latitude with the opposite sign. For this projection, the standard parallel is by definition fixed at 45º.
This projection is a specific case of the Equidistant Cylindrical projection, with standard parallels at 45ºN and S.
On the sphere, this projection can have an arbitrary, oblique aspect, as controlled by the
Originproperty of the
axesm-based map. On the ellipsoid, only the equatorial aspect is supported.
landareas = shaperead('landareas.shp','UseGeoCoords',true); axesm ('giso', 'Frame', 'on', 'Grid', 'on'); geoshow(landareas,'FaceColor',[1 1 .5],'EdgeColor',[.6 .6 .6]); tissot;
Introduced before R2006a