GGR272H1 Lecture Notes - Lecture 5: Equirectangular Projection, Scale Factor, Srf 1
Document Summary
Globe (3d, cumbersome, no detail, but no distortion) vs. map (2d, easier to measure distance, areas, can show more detail, portable, cheaper, distortion). Projection - transformation of 3d earth to a 2d map. Goal - flat map with scale of 1:100,000,000. Full sized earth -> small reference globe: principal scale = reference globe radius/ earth"s radius, transfer to flat map -> point to point, on 2d map - circumference at equator = circumference at 700 n parallel. North pole - is a point on the globe, but a line on the map. Choose projection that doesn"t distort the feature that you want. Projecting shadows onto paper (light bulb inside wire mesh globe) Standard point or line is where globe touches developable surface (no distortion at the standard line - paper is touching globe) Scale factor (local scale/ principal scale) - local scale is the scale on the map (location on map with no distortion.
