(If you rotate the globe before projecting then the parallels and meridians will not. The Columbia Electronic Encyclopedia, 6th ed. The most well-known map projection is the Mercator projection. Since 1998 the National Geographic Society has used a modified azimuthal projection, the Winkel tripel projection, which produces a less distorted representation of the landmasses near the poles than the Robinson projection (see below). A navigator taking the shortest route between two points (always part of a great circle) can plot his course on a gnomonic projection by simply drawing a straight line between the two points. The gnomonic projection has the useful property that all great circles (not just those that pass through the central point) appear as straight lines conversely, all straight lines drawn on it are great circles. You will need to vary the Coord attribute from (-1,-1) to (+1,+1) over the quad. Step 2: Run the following fragment shader. You can do this by binding the textures to FBOs and using glBlitFramebuffer (). The equirectangular projection (also called the equidistant cylindrical projection or la carte paralllogrammatique projection), and which includes the special case of the plate carre projection (also called the geographic projection, lat/lon projection, or plane chart), is a simple map projection attributed to Marinus of Tyre, who Ptolemy claims invented the projection about AD 100. If the central point is a pole, then the meridians (great circles) radiate from that point and parallels are shown as concentric circles. Step 1: Copy your six textures into a cube map texture. In all azimuthal projections, the tangent point is the central point of a circular map all great circles passing through the central point are straight lines, and all directions from the central point are accurate. The point light source may be located at the globe's center (gnomonic projection), on the globe's surface directly opposite the tangent point (stereographic projection), or at some other point along the line defined by the tangent point and the center of the globe, e.g., at a point infinitely distant (orthographic projection). In an azimuthal projection a flat sheet of paper is tangent to the globe at one point.
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