A method for estimating unknown parameters (pan angle (.psi.), instantaneous tilt angle (.tau.) and road geometry of an upcoming road segment) for a vehicle object detection system. The vehicle object detection system is preferably a forward looking, radar-cued vision system having a camera, a radar sensor and an processing unit. The method first estimates the pan angle (.psi.), then corrects the coordinates from a radar track so that pan angle (.psi.) can be treated as zero, and finally solves a least squares problem that determines best estimates for instantaneous tilt angle (.tau.) and road geometry. Estimating these parameters enables the vehicle object detection system to identify, interpret and locate objects in a more accurate and efficient manner.