@article{fdi:010066049,
  title = {{A}ttenuating the bidirectional texture variation of satellite images of tropical forest canopies},
  author = {{B}arbier, {N}icolas and {C}outeron, {P}ierre},
  editor = {},
  language = {{ENG}},
  abstract = {{Q}uantifying and mapping dense tropical forest structure at region to country level have become pressing needs, notably but not exclusively for assessing carbon stocks as part of the {R}educing {E}mission from {D}eforestation and forest {D}egradation ({REDD} +) process. {F}ourier texture features from very high spatial resolution passive optical data have shown good potential as non-saturating proxies for stand parameters, including above-ground biomass, within required standards of precision and accuracy. {T}hese proxies are, however, sensitive to acquisition geometry (sun view angles), even for acquisition geometries usually in use in {VHR} sensors, hampering regional or multi-temporal studies combining multiple acquisitions. {O}ur aim was to improve the understanding of this variation formalized in the bidirectional texture function ({BTF}), and find ways to mitigate it. {W}e used simulated stands and the {D}iscrete {A}nisotropic {R}adiative {T}ransfer ({DART}) model, as well as a collection of {I}konos images over a forest site near {S}antarem ({P}ara, {B}razil). {BTF} proved dependent on forest structure and displayed strong anisotropy with respect to forward vs. backward scattering modes. {B}ut it remained approximately constant over a large range of angular configurations in forward mode, thereby allowing operational use without any correction. {T}his range could be broadened by correcting bias using empirical {BTF} fitting or (more practically) by inter-calibrating {F}ourier spectra when some overlap area is available between images. {P}rediction of a forest structure parameter ({D}-max, the estimated maximum trunk diameter class) using images in varying configurations then remained unbiased and below 15% relative {RMSE} except in the vicinity (+/- 10 degrees in the principal bidirectional plane) of the hotspot direction. {N}ear hotspot directions need to be proscribed, as the absence of visible shadows impedes textural description. {T}hese results, and the increasing availability of large swath {VHR} sensor constellations (e.g. {SPOT} 6-7), open the way to operational broad scale applications for forest characterization, above-ground biomass mapping and multitemporal degradation monitoring.},
  keywords = {{V}ery high spatial resolution ; {P}assive optical imagery ; {F}ourier transform ; {T}exture ; {T}ropical forest ; {B}idirectional texture function ; {R}adiative transfer model ; {ZONE} {TROPICALE}},
  booktitle = {},
  journal = {{R}emote {S}ensing of {E}nvironment},
  volume = {171},
  numero = {},
  pages = {245--260},
  ISSN = {0034-4257},
  year = {2015},
  DOI = {10.1016/j.rse.2015.10.007},
  URL = {https://www.documentation.ird.fr/hor/fdi:010066049},
}