XE33PVR::Lab3 - 2D Homography

Introduction

The goal of the lab is to learn how to map points from one image to another and to compute a 2D homography from point correspondences.

Training case

Download the following images to your local directory:

These two images are related by 2D projective transformation. Use matlab function gimput to obtain 4 correspondences (4 points in the first image and 4 corresponding points in the second image). Write a function H=computeH(u1,u2) that computes the 3x3 transformation matrix from point correspondences. Try different minimum sets of corresponding pairs (i.e. 4 correspondences) and observe the variability in the quality of the result depending on particular selection of the 4 corresponding pairs. Specifically, try 4 corresponding pairs which lie close to a single line. Explain the reasons for the dependency of the result on particular selection of the 4 correspondences. Do display results write a script / function that will use ginput to obtain a point in the first image and will draw corresponding point in the second image using H.

Assignment 2


[XE33PVR labs | Responsible: Ondrej Chum ]
Last modified 19 Oct 2008.