Speaker
Description
Mapping of tree height is of great importance for management, planning, and research related to agroforestry parklands in Africa. In this work, we study spotlight-mode TanDEM-X data for tree height mapping in Saponé, Burkina Faso, a test site characterised by a low average canopy cover (~15%) and a mean tree height of 9.0 m. Seven TDM acquisitions from January-April 2018 are used to create high-resolution (~3 m) maps of interferometric phase height and mean canopy elevation. A model-based processing approach is developed, compensating for some effects of the side-looking geometry of SAR. Compared with phase height, mean canopy elevation provides a more realistic canopy height map, a better tree positioning accuracy, and better tree height estimation performance when assessed using 915 trees inventoried in situ and representing 15 different species/genera. Two bias effects are observed, discussed, and compensated using empirical models. The best-performing model using only TDM data provides tree height estimates with a standard error (SE) of 2.8 m (31% of the average height) and a correlation coefficient of 75%. The estimation performance is further improved when TDM height data are combined with in situ measurements. This is a promising result in view of future synergies with other remote sensing techniques or ground measurement-supported monitoring of well-known trees.
