Margin-based feature selection for hyperspectral data

A margin based feature selection approach is explored for hyperspectral data. This approach is based on measuring the confidence of a classifier when making predictions on a test data. Greedy feature flip and iterative search algorithms, which attempts to maximise the margin based evaluation functions, were used in the present study. Evaluation functions use linear, zero-one and sigmoid utility functions where a utility function controls the contribution of each margin term to the overall score. Results obtained by margin based feature selection technique were compared to a support vector machine based recurring feature elimination approach. Two different Hyperspectral data sets, one consisting of 65 bands (DAIS data) and other with 185 bands (AVIRIS data) were used. With DAIS data, the classification accuracy by greedy feature flip algorithm and sigmoid utility function was 93.02% using a total of 24 selected features in comparison to an accuracy of 91.76% with full set of 65 features. Results suggest a significant increase in classification accuracy with 24 selected features. The classification accuracy (93.4%) achieved by the iterative search margin based algorithm with 20 selected features using sigmoid utility function is also significantly more accurate than that achieved with 65 features. To judge the usefulness of margin based feature selection approaches, another hyperspectral data set consisting of 185 features was used. A total of 65 selected features were used to evaluate the performance of margin based feature selection approach. Results suggest a significantly improved performance by greedy feature flip based feature selection technique with this data set also. This study also suggest that margin based feature selection algorithms provide a comparable performance to support vector machine based recurring feature elimination approach.