CV Mesh Split Long Edges

Refines a mesh until no triangle has an edge longer than max_edge, by repeatedly bisecting the longest edge (one triangle becomes two). Only coarse regions grow, so it costs about half the triangles a uniform 1->4 subdivision needs for the same result. This exists for cv2.rapid: extractControlPoints interpolates its 3D control points LINEARLY between consecutive silhouette VERTICES, using a blend factor taken from screen-space distance - so a control point between two far-apart vertices is wrong by roughly L_px^2/(16*fx) in depth, and its 2D position by the chord sagitta L_px^2/(8*R_px) on a curved silhouette, where L_px is the ON-SCREEN spacing of silhouette vertices. Neither error shrinks if you render at a higher resolution - they are geometric, not raster. Measured on a 3624-triangle vehicle at fx=900, 8 m away: the untouched mesh puts control points up to 23 px off their own 3D points and tracking DIVERGES; at L_px<=80 (5960 triangles, +14% tracking time) that error is 0.9 px and the same sequence tracks to 3 px. Rule of thumb: max_edge = 80 * distance / fx. Below L_px~20 the raster quantization floor takes over and further splitting buys nothing.