Geocart Projections

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McBryde S3


Geocart menu class: Pseudocylindric
Equal area


Meridians: Where the central meridian extends across the Equator, it is a straight line 0.44 as long as the Equator. Other central meridians in the usual interrupted form are straight and half as long. Other meridians are equally spaced sinusoidal curves, bending slightly at latitudes 55°51' N. and S., and all are concave toward the local central meridian.
Parallels: Straight parallel lines, perpendicular to the central meridian(s). Equally spaced between latitudes 55°51' N. and S. Gradually closer together beyond these latitudes
Poles: Interrupted straight lines totaling 0.31 the length of the Equator
Symmetry: About the central meridian or the Equator (in uninterrupted form)


True along every latitude between 55°51' N. and S. and along the central meridian within the same latitude range. Constant along any given latitude; same for the latitude of opposite sign.


Same as the Sinusoidal projection between latitude 55°51' N. and S. Same as the McBryde-Thomas Flat-Polar Sinusoidal projection beyond this range. McBryde S3 is almost always used in the interrupted form and has several central meridians.


World map interrupted to show oceans or land masses, by McBryde


Developed by F. Webster McBryde (1908- ) of Potomac, Md., in 1977 as a merging of the Sinusoidal with the McBryde-Thomas FlatPolar Sinusoidal projection at the parallels of identical scale on the two projections, latitudes 55°51' N. and S.
U.S. Patent by McBryde.

Similar projections

Identical with the Sinusoidal between latitudes 55°51' N. and S.; identical with the McBryde-Thomas Flat-Polar Sinusoidal poleward of those latitudes, except that those portions are closer to the Equator than they are on the McBryde-Thomas Flat-Polar Sinusoidal projection itself.
McBryde merged projections in several other similar combinations, also in 1977.

Description adapted from J.P. Snyder and P.M. Voxland, An Album of Map Projections, U.S. Geological Survey Professional Paper 1453. United States Government Printing Office: 1989.