Zenithal Stereographical Polar Projection
 Lines of Latitude •Equator •Latitudes Lines of Longitude •Prime Meridian •Longitudes Relationships Facts on Earth Zenithal Projections •Gnomonic Polar •Gnomonic Equatorial •Stereographic Polar •Stereographic Equatorial •Orthographic Polar •Orthographic Equatorial Simple Conic Projection Cylindrical Equal-area Projection References Figure A Figure B Figure C Stereographic projections are created by projecting from a point at one end of the diameter in a circle to a projection plane which sit tangential to the other end of the diameter. This situation is clearly depicted in Figure A where the light source comes from point A with white rays radiating out of it. Geometrically, the light source sits on the bottom end of diameter AB. In terms of geography, the light source sits on the south pole of the earth with the projection plane CI on the north pole, thus making the projections on this plane a polar projection. Visually, one can think of the stereographic projection as being created by the shadows casted upon the projection plane CI by the parallels and meridians. With the yellow lines representing parallels and the angle the blue lines makes withe the equator representing angular distance away from the equator EF, shadows of parallels are located at the intersection of the light rays with the plane of projection such as C, B, D, E, F, G, H, and I. As noted in the picture, these rays all goes through the same intersection point made by the parallel with the circle. When looking upon this plane, latitudes will appear as circles whose radius is equal to the distance the polar axis AB is away from such intersections as C, B, D, E, F, G, H, and I as illustrated in Figure B. Mathematically, this distance can be calculated using circle geometry. Referring to Figure A, if an arbitrary latitude JK is chosen, its angular distance is