Efficient calibration for multi-plane homography using a laser level

An efficient calibration method for multi-plane homography is proposed in this paper. Two laser levels are used to cast laser lines to construct virtual poles in the environment without deploying real objects. HSV color model, Hough transform, and least squares method are applied to locate the laser lines in the captured images. Using the features of vanishing line and the view-invariant cross-ratio model, the 3-D coordinate of the camera can be estimated. The multi-plane homography between camera image and the world space can be derived based on two layers homography. The first layer homography relates the ground and the image, whereas the second layer homography can be efficiently obtained using the first layer homography and the virtual poles. Experimental results show that the virtual poles and the derived homography are both accurately estimated.