In one embodiment, a system, method and computer readable media are disclosed for trimming geographic data that defines polygons to boundaries of a quadrangle. The geographic data is converted to map coordinates in a novel azimuthal map projection. Each map projected point in the azimuthal map projection has an azimuthal angle that is proportional to longitude of the point, and has a radius from the center of the azimuthal map projection that is proportional to both the longitude and latitude of the point. Polygons are trimmed along a lower limit of the quadrangle and along an upper longitude limit of the quadrangle using the azimuthal map projection. The map coordinates in the azimuthal map projection are then converted back to geographic data.