Airborne Non-metric Video Image Orientation Determination Using Two GPS Receivers

Abstract

In theory, using a GPS system in conjunction with an Inertial Measurement Unit (IMU) enables photogrammetric mapping even without using ground control points. But such systems are expensive, not highly accessible, and not suited for close range photogrammetric measurements based on airborne video photography. This paper presents an alternative modified system which enables setting the position and attitude of video images acquired from a helicopter. It is a fairly simple system comprised of an analogical video camera and two kinematic GPS rover receivers. One GPS antenna is located close to the camera and used to locate the camera at the time of the image acquisition. The second antenna is suspended underneath the helicopter. It functions as a flown control point and appears in all the video images. Thus, a photogrammetric model or strip is created in which the coordinates of the exposure point and of one of its image points are always known in all the photographs. The solution process for such a photogrammetric model or strip is presented, as well as, the results and accuracy of the experiments that were carried out to test the system.