A Thin Lens Based Camera Model for Depth Estimation from Defocus and Translation by Zooming

Depth recovery is a central concern in computer vision, and many methods were proposed for the monocular depth estimation by zooming as well as focusing and irising. In the past, there are two distinct approaches in depth by zooming; one is from motion parallax along the optical axis using a pinhole camera model, and the other from defocus using a thin lens camera model. This paper presents a new camera model that accounts for both effects of defocus and lens center translation by zooming. We first discuss the optical properties of zoom lenses, then present a thin lens based camera model that describes the mutual relationship between zoom, focus and iris parameters. Using this model with calibration results, we have performed some experiments with real images and evaluated the accuracy of the depth information recovered from defocus and lens center translation. Experimental results have demonstrated the validity of our camera model and also shown its applicability to the depth estimation from defocus and translation by zooming.