Pose from four known points
A square tag with known object-frame corners projects to fixed observed pixels. You drag the estimated pose and the reprojection error updates; the solve button runs a damped Gauss–Newton loop that recovers the pose the way a real PnP does.
Try this
Get the error as low as you can by hand, note the number, then press solve.
Where this lab comes from
What Is PnP? Finding Where the Camera Is from Known PointsLesson 4 of Camera Geometry. PnP finds where a calibrated camera stood and which way it faced from points whose positions are known and where they appear in one photo. On OpenCV's chessboard photos it returns the calibration's own pose to 0.00002°, four corners are enough for 0.27 px, and with five corners found wrong a plain fit moves the camera 2.5 squares where RANSAC moves it 0.008.
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.
- The scene, and what the camera sees — Orbit a 3-D scene on the left; the pinhole view updates on the right.