Easy Camera Calibration Using Inter-Image Homographies

Authors:
Xiaochun Cao and Hassan Foroosh

Affiliations:
School of Computer Science
University of Central Florida

Email addresses:
{xccao, foroosh}@cs.ucf.edu

Abstract:

This paper addresses the problem of calibrating a pinhole camera using
images of a symmetric object. Assuming a unit aspect ratio,and zero
skew, we show that inter-image homographies can be expressed as a
function of the principal point. By minimizing the symmetric transfer
error of geometric distances, we thus obtain an accurate solution for
the calibration parameters. We show that the approach can also be
extended to a calibration technique using images of a 1D object with a
fixed pivoting point. The advantage of our approach over existing
methods is that we rely only on inter-image homographies, and hence no
knowledge of the world to image homography is required. To demonstrate
the effectiveness of the approach both in the case of symmetric objects
and 1D objects, we present the processing results for both synthetic
and real images, and provide a quantitative comparison with Zhang^Òs
flexible calibration technique (2000), and his 1D calibration method
(2002).