1. A laser sensor useful in determining the shape of a vehicle, the sensor comprising: laser means for determining a range from the sensor to points on a vehicle when the vehicle travels within a sensing zone of the sensor and for providing range data outputs corresponding to sensor angles for ranges from the sensor to the points on the vehicle; means for scanning the laser means within a plane across the vehicle for determining the range for the points on two dimensions of the vehicle, the scanning means having a scanning direction generally orthogonal to a direction of travel for the vehicle the scanning means providing means for determining the range and a corresponding sensor angle for each point within the scanning plane; means for determining a vehicle speed; and means for processing the ranges, angles and vehicle speed for providing a multiplicity of two dimensional cross-sectional profiles of the vehicle, the processing means positioning the profiles based on the vehicle speed for providing a three dimensional image representative of the vehicle, the image useful in classifying the vehicle.