Mapping Tree Height in Burkina Faso Parklands with TanDEM-X,
Auteur(s): Soja, M.J.; Karlson, M.; Bayala, J.; Bazié, H.R.; Sanou, J.; Tankoano, B.; Eriksson, L.E.B.; Reese, H.; Ostwald, M.; Ulander, L.M.H.
Auteur(s) tagués: Hugues Roméo BAZIE ;
Résumé

Mapping of tree height is of great importance for management, planning, and research
related to agroforestry parklands in Africa. In this paper, we investigate the potential of spotlightmode
data from the interferometric synthetic aperture radar (InSAR) satellite system TanDEM-X
(TDM) for mapping of tree height 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 jointly to create high-resolution (~3 m) maps of interferometric phase height and mean
canopy elevation, the latter derived using a new, model-based processing approach compensating
for some effects of the side-looking geometry of SAR. Compared with phase height, mean canopy
elevation provides a more accurate representation of tree height variations, 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. We observe and discuss two bias effects, and we
use empirical models to compensate for these effects. 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.

Mots-clés

interferometric synthetic aperture radar (InSAR); two-level model (TLM); geometric corrections; spotlight data; vegetation height

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