The scene, and what the camera sees
A real WebGL scene beside the image a pinhole camera forms of it, with the camera's field of view derived from a focal length in pixels. The two views stay in sync, so moving the object moves the projection.
Try this
Push the ball away from the camera and watch its projected radius shrink by the same factor its distance grew.
Try it: the red-ball scene in 3-D
Where this lab comes from
The Camera Matrix: K, [R|t] and P, Worked on a Real ChessboardLesson 2 of Camera Geometry. A camera is one 3×4 matrix: the focal lengths and image centre in K, where the camera stands in [R|t], and their product P, which sends any point of the world to a pixel. Worked on one corner of a chessboard in OpenCV's own calibration photos, checked against cv2.projectPoints, and taken apart again.
More in cameras and geometry
- Focus, aperture and depth of field — Move the subject and watch the focus plane and the blur follow.
- Four ways a fisheye maps angle to radius — Plot r(θ) for the classical designs against a fitted curve.
- Straight lines that bow — Brown–Conrady radial and tangential terms on a pixel grid.