Asteroid, Baseball, etc. (obj mesh) Projected Surface Area

Calculate the projected area into wind axes for an obj (wavefront) that is a convex hull.

For simple shapes where the hidden faces are trivially removed (normal pointing in opposite direction), the surface area is calculated.

Here the surface area of two asteroids is estimated from 3d printing files shared at NASA (https://nasa3d.arc.nasa.gov/models). The code reformats obj files (other 3d formats can easily be converted to obj with tools online). The projected areas can be used to reverse engineer size/shape or predict brightness for educational astronomy.

The code can be used to calculate projected areas of baseballs, footballs, etc., for computing the coefficient of atmospheric drag.

The examples use the aerospace tool box function to get direction cosine matrices (dcm), but this can be calculated independently, so that tool box is not an extreme dependency.