Abstract: A kind of trifocal points curve is mainly researched. Firstly, the concept and formula of this
kind of trifocal points curve is presented, and the properties of the trifocal points curve are also
analyzed. Secondly, quantitative and shape analysis is made on the trifocal points curve by turning its
parameters, and the programming method is used to realize the shape analysis of the trifocal points
curve. The properties and rules of the trifocal points curve are analyzed and summarized. Finally, the
parameters of the trifocal points curve are calculated by using of the image processing and fitting
method which is the contours of images of some objects. Moreover, the error analysis is given and the
fitting curve is described. The experiment results show that the trifocal points curve can be the precise
representation of the contours of the images of some natural objects.

Key words: trifocal points curve, natural object, image processing, curve fitting, error analysis