The advantage of reflectance measurements in radiometric adjustment of aerial imagery

Abstract. The radiometric adjustment of aerial imagery is a process of very high importance considering the influences this step can generate not only on the look of the image data (white balance), but even more importantly on derived information like indices (NDVI). In comparison to the Aerial Triangulation where it is relatively straight forward to set up thresholds that need to be met in order to achieve a high-quality result, the world of radiometric adjustment is dramatically different. There is no single standard or guideline that dictates what a high-quality radiometric result will look like. Apart from these challenges there is also a rather big gap between the rich and longstanding academic work done in the field of radiometry and actual application in real-life projects. The biggest discrepancy is the usage of single images, especially when dealing with absolute radiometry approaches versus multiple thousand color balanced images in a single block in an actual production environment. In this paper, we present the advantages of utilizing reflectance measurements as a method to stabilize radiometric adjustments, as well as utilizing them as anchor to create indices like the NDVI that correspond to the value range given by literature.