Create some Blender-rendered chessboards to test the hypothesis whether perpendicular camera movement to to-be-triangulated object-points results in less depth error than camera movement towards the to-be-triangulated object-points. Results seem to slightly support the hypothesis, although the noise-less Blender-renders might explain the low depth error in both cases.
Optimize Linear-LS triangulation, in preparation of Iterative-LS triangulation.