Evaluating the effectiveness of smoothing algorithms in the absence of ground reference measurements

Time series of vegetation indices like NDVI are used in numerous applications ranging from ecology to climatology and agriculture. Often, these time series have to be filtered before application. The smoothing removes noise introduced by undetected clouds and poor atmospheric conditions. Ground refe...

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Bibliographic Details
Published in:International journal of remote sensing 2011-01, Vol.32 (13), p.3689-3709
Main Authors: Atzberger, Clement, Eilers, Paul H. C
Format: Article
Language:English
Subjects:
Algorithms
Animal, plant and microbial ecology
Applied geophysics
Biological and medical sciences
Clouds
data collection
Earth sciences
Earth, ocean, space
ecology
Exact sciences and technology
Fundamental and applied biological sciences. Psychology
General aspects. Techniques
geostatistics
Grounds
image analysis
Imagery
Indicators
Internal geophysics
meteorology and climatology
Smoothing
Teledetection and vegetation maps
Time series
time series analysis
Vegetation
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Summary:Time series of vegetation indices like NDVI are used in numerous applications ranging from ecology to climatology and agriculture. Often, these time series have to be filtered before application. The smoothing removes noise introduced by undetected clouds and poor atmospheric conditions. Ground reference measurements are usually difficult to obtain due to the medium/coarse resolution of the imagery. Hence, new filter algorithms are typically only (visually) assessed against the existing smoother. The present work aims to propose a range of quality indicators that could be useful to qualify filter performance in the absence of ground-based reference measurements. The indicators comprise (i) plausibility checks, (ii) distance metrics and (iii) geostatistical measures derived from variogram analysis. The quality measures can be readily derived from any imagery. For illustration, a large SPOT VGT dataset (1999–2008) covering South America at 1 km spatial resolution was filtered using the Whittaker smoother.
ISSN:1366-5901
0143-1161
1366-5901
DOI:10.1080/01431161003762405