 Automated individual tree crown detection and delineation, ITCD, using remotely sensed data has become increasingly important in monitoring forests. The use of active data such as LIDAR has increased significantly since 1990, while passive data sources have remained largely unchanged. Active data provides greater detail and allows for the exploration of more complex forest conditions, such as closed hardwood forests and urban slash suburban areas. Researchers have also begun to develop new methods for ITCD, taking advantage of the unique characteristics of active data. These advances have allowed for more accurate and efficient monitoring of forests, making ITCD a valuable tool for forest managers. This article was authored by Zhenzhen, Lindy J. Quackenbush and Li Anzhu and Zhang.