1. A method of maneuvering a vehicle in an autonomous driving mode alongside of an object, the method comprising: receiving, by one or more computing devices having one or more processors, sensor data including three-dimensional points of one or more surfaces of the object in an environment of the vehicle; determining, by the one or more computing devices, a two-dimensional contour of the object using the three-dimensional points; determining, by the one or more computing devices, a set of minimum clearance distances between a virtual model of the vehicle defining a cross-sectional area of the vehicle and the two-dimensional contour by determining a height profile of the object as a set of lateral distances between a center line of the virtual model of the vehicle and the two-dimensional contour; and maneuvering, by the one or more computing devices, the vehicle alongside of the object based on at least the determined two-dimensional contour and a predetermined threshold clearance value.