A few snippets of code for drawing points and lines on a map with Sphere / Plane intersections.

This is the first post in a series of basic D3 tutorials aimed at visualizing different geographic projections. which are mathematical methods for flattening the sphere of the Earth onto a flat piece of paper or computer screen.

The first projection to be introduced is the equatorial orthographic projection. This is perhaps the most natural projection, as it depicts a hemisphere of the globe as it appears from outer space. We first saw our planet from this point of view in 1946, but this projection has been in use since the first century BCE.

Like all projections, the orthographic projection is not a perfectly accurate representation of reality. The shapes and areas of all landmasses are distorted — particularly near the edges — in an orthographic projection, which makes it unsuitable for visualization of navigation routes and comparative information.