Fast Stereo Aerial Image Construction and Measurement for Emergency Rescue

In the field of UAV information processing and aerial image processing technology, data collected from MUAV platform is more and more widely used in emergency rescues. The traditional way of aerial photogrammetry, which has a limited accuracy in aerial camera locations from the UAV, makes measurements of the object location on pairwise images inaccurate. A method is presented in this paper to fast construct the stereo aerial image using high-precision GPS and INS data. It also allows users to do correct measurements based on aerial images as the high-frequency DGPS promoting the accuracy and reliability of aerial camera locations. The main steps to construct a stereo aerial image are: 1) image acquisition and overlap calculation, making a route planning for the flight based on the height of the MUAV and the objects types in the flight area to get image sequences with adequate overlap.2) Fast stitching of aerial images: We used high-precision GPS and INS data to pre-align images roughly which would make the matching process much faster and then stitch the images with matched feature points.3) Stereo aerial image synthesis, two mosaic images over the same flight area are synthesized. We adjust the parallax of the synthesized image to a scale properly fitting the human eyes to make it more dynamic. Due to a stable low-altitude flying of the MUAV as well as the high density position and attitude data acquired, it would enable us to measure objects in the stereo image with a longer baseline. In order to verify the practicability and the measurement accuracy of this method, an experiment was done along the Kelan River in Xinjiang. We obtained high-resolution images and accurate camera locations with the MUAV platform. Afterwards, a stereo aerial image was quickly constructed and measurements were taken by improved aerial photogrammetry to get detail information of the image. In the accuracy analysis of the measurements results, it demonstrated fine efficiency and a good accuracy of the method.