A critical synthesis of remotely sensed optical image change detection techniques

State of the art reviews of remote sensing change detection are becoming increasingly complicated and disparate due to an ever growing list of techniques, algorithms and methods. To provide a clearer, synoptic view of the field this review has organised the literature by the unit of analysis and the comparison method used to identify change. This significantly reduces the conceptual overlap present in previous reviews giving a succinct nomenclature with which to understand and apply change detection workflows. Under this framework, several decades of research have been summarised to provide an overview of current change detection approaches. Seven units of analysis and six comparison methods were identified and described highlighting the advantages and limitations of each within a change detection workflow. Of these, the pixel and post-classification change methods remain the most popular choices. In this review we extend previous summaries and provide an accessible description of the field. This supports future research by placing a clear separation between the analysis unit and the change classification method. This separation is then discussed, providing guidance for applied change detection research and future benchmarking experiments.