What's a good calibration object for the extrinsic calibration (rotation + translation) of a depth camera (no color sensor, only depth)? With RGB, people seem to typically use chessboard pattern or some kind of markers. Is there something similar that would work without RGB?
1 Answer
You can use a 3d Marker, e.g. a cube or a another arrangement of three planes. Finding these planes in the Pointcloud/Depth Image is not hard and provides a 6D Pose (if you can distinguish the planes which can be done by using non-90-deg angles).
If you also add visual markers (e.g. checkerboard pattern) to the planes, you can first use a 2d Camera to measure the relative poses of the planes.