I. Introduction
Remote-sensing image processing and analysis play an increasingly significant role in earth observation [1]–[3]. Object detection is a fundamental but challenging task in the remote-sensing community and plays an important role in wide-scope applications including target reconnaissance, land monitoring, and environmental conservation [4]–[7]. For instance, object detection in the remote-sensing system can monitor airports and harbors to obtain the spatial distribution and geographic coordinates of objects such as aircraft and ships [8]–[11]; it can also be used to observe the growth of crops [12]–[14].