3 Matching Annotations
- Feb 2017
Only 23 studies actually integrated both active and passive data sources into the ITCD procedure since 2000 (Figure 2).
Only a small fraction of studies combine LiDAR and Hyperspectral data for the crown delineation phase of analysis.
Another limitation is that few approaches take full advantage of the information contained within remotely sensed data, e.g., using only one band of multispectral imagery  or only the canopy height model derived from LiDAR data . Significant amounts of information are dismissed or neglected during data preparation or processing. The integration of multispectral data and discrete LiDAR data is commonly used to improve tree species classification  and fusion of passive and active remotely sensed data may reduce commission and omission errors in ITCD results .
Excellent point about the importance of integrating all available data to make the best possible crown delineations. In the case of the National Ecological Observatory Network Airborne Observation Platform methods that leverage the LiDAR, hyperspectral, and high-resolution RGB photographic data should have the potential to outperform methods that ignore components of this data.
Comparison of methods continues to be complicated by both choice of reference data and assessment metric; it is imperative to establish a standardized two-level assessment framework to evaluate and compare ITCD algorithms in order to provide specific recommendations about suitable applications of particular algorithms.
An important call for standardized reference data and assessment for moving individual tree crown delineation forward.