In “Distance Determination for an Automobile Environment using Inverse Perspective Mapping in OpenCV , ” S.Tuohy, D.O’Cualain, E. Jones, and M.Glavin at the College of Engineering and Informatics National University of Ireland describe a novel real-time distance determination OpenCV algorithm using an image sensor in an automobile environment. The system uses a forward facing camera placed within the vehicle.
Because it is difficult to determine distances to objects in front of the vehicle with any degree of certainty because of a non linear relationship between the height of an object in a forward facing image and its distance from the camera, they make use of Inverse Perspective Mapping (IPM).
Using IPM, they describe how to transform the forward facing image to a top-down “bird’s eye” view, in which there is a linear relationship between distances in the image and in the real world.
The algorithm is implemented in the C language using the OpenCV libraries and results in a high performance, low overhead system that could be implemented on a low power embedded device in an automotive environment.