glc2000: british isles and northwest europe an evaluation of the spot vegetation sensor for land use...
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GLC2000: British Isles and Northwest Europe
An Evaluation of the SPOT Vegetation Sensor for Land Use Mapping
Erik de Badts
Flowchart
S p line F un c tion H A N T S
V a lida tion
C la ss if ica tion
R e g ion a liza tion
C lo udR e m o va l
W in d ow D efin it iona n d P ro jec tion
Window Definition
Window Definition
• Comparison with NOAA-AVHRR
• PELCOM
Cloud Removal
Spline Function
• Define “Cloudy” Pixels
• Preservation of Original
Pixel Values
• Extrapolations in Beginning
and Ending of Time Series
HANTS (Harmonic
Analysis of Time
Series)
•Lost of Original Pixel Value
•Smoothed Time Series
•No Objective Rules
HANTS Algorithm Explained
0
0.2
0.4
0.6
0.8
1 6 11 16 21 26 31 36
Decade (1996)
ND
VI (
-)
measuredrejectedHANTS
-0.4
-0.2
0
0.2
0.4
0 9 18 27 36
Decade (1996)
ND
VI (
-)
frequency = 0 (average)frequency = 1 (annual cycle)frequency = 2 (6 months cycle)
Original cloud affected and reconstructed cloudfree NDVI time series profile of one pixel
The Fourier components from which the cloudfree NDVI time series profile is reconstructed
Conclusion Cloud Removal
Spline Original HANTS
•Higher Values in Filled Gaps
•Wider Data Range: Extremes
Regionalization
•Improvement Discrimination Process on Difficult Classes
•Misclassification Due to Spectral Confusion Reduces
Classification
• Masks
– Water Bodies
– Urban Areas
– Wetlands
• Classification: Treegrowing with CART (Salford
Systems)
– Forests: Red Wavelengths
– NDVI
• CART
– No Undesired “Mixed” Classes
– Statistical Prove on Separability
Classification
Validation
Accuracy Changewith
Reliability Changewith
PELCOM PELCOMArable Land 78.8% +1,0% 55.6% +23.5%
Pasture 58.7% +7.7% 49.7% +27.8%
NaturalGrassland
15.4% ---- 64.0% ----
DeciduousForest
17.1% -32.7% 27.7% +31.3%
EvergreenForest
45.6% +4.8% 38.0% +145.2%
Mixed Forest 17.1% +13.2% 15.1% +93.6%
Shrubs 57.2% +14.6% 59.6% +18.3%
Wetlands 44.7% +16.6% 15.6% +60.0%
Total Forest 55.3% +6.3% 53.9% +128.4%
•CORINE
–PELCOM
•FOA-Statistics
Validation
•Geometrical Distortion of NOAA: Shift Towards the
Southeast
•Push Broom Wisk Broom
Conclusion
• HANTS : Best Way to Obtain a Cloudfree Time Series
• Treegrowing is a Consistent Method for Classification
• Few Improvement Compared to PELCOM (+1.5%)
NDVI Changes in 2000