Remote Sensing Using
Multi-spectral, Multiangle Polarized POLDER Data
Discrimination
of Inundated and Non-inundated Community Types with Multispectral
Multiangle Polarized POLDER Data  Better
estimates of the areal extent of inundated vegetation types and open water
would greatly reduce the uncertainties in atmospheric methane budget.
We identify a method to estimate the areal extent and distribution of open
water, inundated communities (bogs and fens), and upland boreal vegetation
types using multi-view angle POLDER data. The study site is located
in the vicinity of the southern study area of NASA’s BOREAS project in
central Saskatchewan, Canada. Community identifications were based
on multi-band multi-view angle signatures. We extended the application
of spectral mixture analysis techniques to bi-directional remotely sensed
data to take advantage of the multiple sun/view angle images available
from POLDER. The development of multiple view angle spectral endmembers
for vegetation mapping is a unique approach to image analysis. Bi-directional
spectral mixture analysis (B-DSMA) techniques were evaluated for their
ability to interpret POLDER mixed pixel data and provide areal estimates
of land cover classes using BRDF endmembers. The glitter of specular sunlight
off water bodies provides a strong and unique signature. Further,
community structure, canopy architecture, and phenology are markedly different
between these systems producing significant spectral view angle differences.
The normalized view angle spectra were separated into open water, two dry
upland vegetation types, soil, and wetlands. Those spectra and their
correlation with physical differences among land cover types suggest that
is possible to obtain a good classification for boreal wetlands using POLDER
satellite data.
Diaz Barrios, M.C. S.L. Ustin, G.L. Perry, V.C. Vanderbilt, L.A. Morrissey and G.P. Livingston, F.-M. Bréon, S. Bouffies, M.M. Leroy, M. Herman and J.-Y. Balois. Discrimination of inundated and non-inundated community types with multispectral multiangle polarized POLDER data. IEEE Transactions on GeoScience and Remote Sensing (in press). |
Accuracy of
Multiple View Angle and Nadir Spectral Based POLDER Images for Discrimination
of Inundated and Non-Inundated Community Types  Three
images types from POLDER airborne imagery, nadir looking multi-spectral
bands, multiple view-angle images of the red band, and combined datasets,
were used to classify land cover types at the NASA southern BOREAS study
site in Saskatchewan, Canada. We found that combining multiple view-angle
imagery with nadir viewing multi-spectral bands provided the greatest accuracy
and discrimination of the largest number of inundated and non-inundated
land cover classes. While the nadir looking multi-spectral band data correctly
separated open water from other land cover classes it did not separate
the inundated vegetated regions that define boreal wetlands. Multiple view-angle
data could separate two upland vegetation types and open water but only
one inundated vegetation type.
Diaz Barrios, M.C. S.L. Ustin, G.L. Perry, V.C. Vanderbilt, G.P. Livingston and L.A. Morrissey. 1998. Accuracy of Multiple View Angle and Nadir Spectral Based POLDER Images for Discrimination of Inundated and Non-Inundated Community Types (in preparation). |
Remote
Sensing of High-latitude Wetlands Using Polarized Wide Angle Imagery
 Representing
the areal extent of circumpolar wetlands is a critical step to quantifying
the emission of methane, an important greenhouse gas. Present estimates
of the areal extent of these wetlands differ nearly seven fold, implying
large uncertainties exist in the prediction of circumpolar methane emission
rates. Our objective is to use multi directional and polarization measurements
provided by the French POLDER sensor to improve this estimate. The results
show that wetlands can be detected, classified and their area quantified
using the unique, highly polarized angular signature of the sunglint measured
over their water surfaces.
Perry, G.L., J.A. Stern, V.C. Vanderbilt, S.L. Ustin, M.C. Diaz Barriois, L.A. Morrissey, G.P. Livingstone, F.-M. Breon, S. Bouffies, M.M. Leroy, M. Herman, and J.-Y. Balois, Remote Sensing of high-latitude wetlands using polarized wide angle imagery. SPIE Conf. Vol 3118, Imaging Spectrometry III p. Presented at the 42nd Annual SPIE meeting, July 27 to Aug. 1, 1997, San Diego, CA. |
Discrimination
of Wetland and Non-wetland Community Types with Multi-spectral, Multi-angle,
Polarized Data  The
areal representation of boreal wetlands, the source areas for methane,
an important greenhouse gas, is poorly known -- estimates differ nearly
seven fold. Here our objective was to investigate the feasibility of 1)
using POLDER data to discriminate wetlands as distinct from other ground
covers and 2) classifying wetlands according to whether they are open-water
areas or fens. The results show that the visually blinding glitter of sunlight
off ruffled water surfaces provides a strong, unique, angular signature
reflection which is characteristic of wetlands and uncharacteristic of
other common cover types.
Vanderbilt, V.C., G.L. Perry, J.A. Stearn, S.L. Ustin, M.C. Diaz Barrios, S. Zedler, J. Syder, L.A. Morrissey, G.P. Livingston, F.-M. Breon, S. Bouffies, M. Leroy, M. Herman, and J.-Y. Balois. 1997. Discrimination of wetland and non-wetland, community types with multi-spectral, multi-angle, polarized data. 7th Int. Symp. Physical Measurements and Signatures in Remote Sensing, April 7-11, 1997, Courchevel, France. |
Apart from the atmospheric effects, the spectral variation of the light reflected by canopies originates from the leaves, the soil or the other vegetation elements such as branches and fruits. Many models mimic the directional variability of canopy reflectance at a given wavelength (see the review by Goel, 1988 for example). Combining a leaf spectral model with a canopy directional model provides a powerful tool to analyze this problem. The main objective of the 1991 POLDER/AVIRIS experiment in Camargue was to provide a consistent data set over various canopies in order to test the applicability of the theory. The experiment, part of the 1991 MAC Europe experiment, involved simultaneous data collection using two sensors: AVIRIS (Vane, 1987) and POLDER (Deschamps et al, 1990) which measures the bidirectional and polarization properties of the targets at 670 and 880nm wavebands.
Baret, F., C. Leprieur, S. Jacquemoud, V. Carrere, X. F. Gu, M. Steven, V. Vanderbilt, J. F. Hanocq, S. Ustin, G. Rondeaux, C. Daughtry, L. Biehl, R. Pettigrew, D. Modro, H. Horoyan, T. Sarto, C. Despontin, and H. Razafindraibe. (1992). The 1991 AVIRIS/POLDER Experiment in Camargue, France. Summaries of the Third Annual JPL Airborne Earth Science Workshop: AVIRIS Workshop, Pasadena, CA, vol. 92-14, pp. 75-77.