 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 accuracy when compared to passive data, allowing for more complex forest conditions to be monitored. Furthermore, advances in ITCD algorithms have allowed for the exploration of more complex forest types, including closed hardwood forests and suburban slash urban forests. Despite this progress, there remains a need for standardization in terms of assessment metrics and reference data. This article was authored by Zhenzhen, Lindy J. Quackenbush and Lianzhu and Zhang.