Compress a real km vector into world-render units, preserving its true
direction exactly — compress the radial magnitude once, then scale every
axis by that single factor, never each axis independently (which warps a
circle/ellipse into a rounded square: two points at the same true radius
get squeezed by different amounts depending on how their distance splits
across axes). Also remaps orbital (x, y, z) into three.js's Y-up
convention: orbital z (out of the reference plane) becomes world y.
Compress a real km vector into world-render units, preserving its true direction exactly — compress the radial magnitude once, then scale every axis by that single factor, never each axis independently (which warps a circle/ellipse into a rounded square: two points at the same true radius get squeezed by different amounts depending on how their distance splits across axes). Also remaps orbital (x, y, z) into three.js's Y-up convention: orbital z (out of the reference plane) becomes world y.