Rapid technological progress has made mobile devices increasingly valuable for scientific research. This paper outlines a versatile camera-based water gauging method, implemented on smartphones, which is usable almost anywhere if 3D data is available at the targeted river section. After analysing smartphone images to detect the present water line, the image data is transferred into object space. Using the exterior orientation acquired by smartphone sensor fusion, a synthetic image originating from the 3D data is rendered that represents the local situation. Performing image-to-geometry registration using the true smartphone camera image and the rendered synthetic image, image parameters are refined by space resection. Moreover, the water line is transferred into object space by means of the underlying 3D information. The algorithm is implemented in the smartphone application “Open Water Levels”, which can be used on both high-end and low-cost devices. In a comprehensive investigation, the methodology is evaluated, demonstrating both its potential and remaining issues.
- Exterior orientation
- Image-to-geometry registration
- Outdoor application
- Sensor fusion