CAHVOR is a camera model used in machine vision for three-dimensional measurements. It models the transformation from the object domain to the image domain using vectors C, A, H, and V and corrects radial lens distortions with a vector O and a triplet R. In photogrammetric mapping the camera model is usually represented by collinearity equations with interior and exterior orientation parameters. In NASA's planetary missions the CAHVOR model has been widely used for rover navigation and scientific exploration. On the other hand, a photogrammetric model is often needed in mapping and photogrammetric data processing systems. This paper presents a method for conversions between the CAHVOR model and the photogrammetry model. A numerical example is given to validate the conversion equations.