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23 October 2014 A comparison of feature selection methods for multitemporal tree species classification
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The problem of feature selection is a significant one in classification problems, where the addition of too many features to the classification fails to lead to significant increases in classification accuracy. This problem is especially significant within the context of multitemporal remote sensing classifications, where the costs and efforts associated with the acquisition of additional imagery can be extensive. It would thus be beneficial to identify the most important seasons for acquiring imagery for specific land cover types. This study uses a phenologically-adjusted 21 date RapidEye time-series in order to evaluate two methods of feature selection. The two methods compared in this study are a genetic algorithm (GA) and a semi-exhaustive method (EXH), both of which compare permutations of sequential date and band combinations. These methods are employed using a seven class support vector machine classification on a Normalized Difference Vegetation Index (NDVI)-transformed dataset. Overall accuracy (OAA) is used as the performance metric, and OAA significance is assessed using the McNemar test. The results from the feature selection methods are compared on the basis of phenological seasons selected across all iterations and the ideal number of combinations, based on the ratio of better performing classifications to all other classifications. The results suggest that the GA has a moderate but insignificant correlation when compared with the EXH for identifying ideal phenological seasons (overall Spearman’s ρ= 0.60, p = 0.13), but is comparable when considering the number of seasons and image combinations.
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Kyle Pipkins, Michael Förster, Anne Clasen, Tobias Schmidt, and Birgit Kleinschmit "A comparison of feature selection methods for multitemporal tree species classification", Proc. SPIE 9245, Earth Resources and Environmental Remote Sensing/GIS Applications V, 92450V (23 October 2014);

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