Camera Calibration

Refer to http://www.cse.iitd.ernet.in/~suban/vision/geometry/node39.html

In the orthographic camera model, every object has the same magnification; while in the weak perspective model, distant object looks smaller. Objects have similar $z$ have the same magnification factor.

Weak perspective projection can be considered as a combination of perspective and orthographic projection.

Refer to Simplified Camera Projection Models, pdf.

Projective Geometry

  • ideal points, points at infinity
  • line at infinity, plane at infinity
  • circular points, absolute conic
  • vanishing points
    • if a point lies on the plane at infinity, then its image is called vanishing point
    • two parallel lines intersect at a point on the plane at infinity, so the image of the intersection is a vanishing point
    • it can be used for camera calibration! (1) identify two vanishing points; (2) identify the angle of the two corresponding lines; (3) we get a constraint; (4) the intrinsics have 5 degree of freedom, so we need to find five pairs of vanishing points
    • by vanishing points, we can use just one image to calibrate an image!
  • vanishing line
    • it is the image of the plane at infinity
    • all vanishing points lie on the vanishing line
  • image of the absolute conic (IAC)
    • it is useful for camera calibration!

todo

adaboost, graphical models, SVM face recognition (pattern matching)

boosting gbdt xgb lgb, auc area, roc curve, light gbm random forest, xgboost

crf (conditional random field)

word2vec, lstm

CS230: Deep Learning

Single View Metrology and this assignment and refer to this one