1. A method of providing a road departure warning alert in a vehicle comprising: creating a road texture model based on a vehicle image received from a vehicle camera; retrieving map imagery based on an initial vehicle location estimate; determining a refined vehicle location using visual egomotion based on the vehicle image and the map imagery; creating a road boundary model describing the edges of the road on which the vehicle is located based on the road texture model and the refined vehicle location; creating a road departure model based on the road boundary model and vehicle odometry information; and warning a vehicle operator based on the road departure model.