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Tony's Intertwingled Memex • Reference Manual

3D Coordinate Mapping

Formulas & Definitions

In robotic systems and autonomous navigation, depth cameras (like RGB-D sensors) represent the surroundings as a 3D point cloud. A robot arm is situated at the origin (0,0,0)(0,0,0)(0,0,0), and its software needs to calculate distances between detected objects to prevent collisions.

A depth sensor detects a cylindrical obstacle with a safety envelope modeled as a sphere centered at C(3,−4,2) metersC(3, -4, 2)\text{ meters}C(3,−4,2) meters with a radius of r=1.5 metersr = 1.5\text{ meters}r=1.5 meters. A point obstacle is detected at P(4,−2.5,3) metersP(4, -2.5, 3)\text{ meters}P(4,−2.5,3) meters.

  1. Find the distance between the robot arm at the origin O(0,0,0)O(0,0,0)O(0,0,0) and the center of the spherical safety envelope CCC.
  2. Determine the standard equation of the spherical safety envelope.
  3. Calculate the distance from the point obstacle PPP to the center of the safety envelope CCC. Determine if the point obstacle has breached the safety envelope (i.e., is it inside the sphere?).