Design and test of a multi-camera based orthorectified airborne imaging system

Airborne imaging platforms have been applied to such diverse areas as surveillance, natural disaster monitoring, cartography and environmental research. However, airborne imaging data can be expensive, out of date, or difficult to interpret. This work introduces an Orthorectified Airborne Imaging (OAI) system designed to provide near real time images in Google Earth. The OAI system consists of a six camera airborne image collection system and a ground based image processing system. Images and position data are transmitted from the air to the ground station using a point to point (PTP) data link antenna connection. Upon reaching the ground station, image processing software combines the six individual images into a larger stitched image. Stitched images are processed to remove distortions and then rotated so that north is pointed up (orthorectified). Because the OAI images are very large, they must be broken down into a series of progressively higher resolution tiles called an image pyramid before being loaded into Google Earth. A KML programming technique called a super overlay is used to load the image pyramid into Google Earth. A program and Graphical User Interface created in C# create the KML super overlay files according to user specifications. Image resolution and the location of the area being imaged relitive to the aircraft are functions of altitude and the position of the imaging cameras. Placement of OAI images in Google Earth allows the user to take advantage of the place markers, street names, and navigation features native to the Google Earth environment.