MSMD: maximum separability and minimum dependency feature selection for cropland classification from optical and radar data

ABSTRACT

Cropland classification using optical and full polarimetric synthetic aperture radar (PolSAR) images is a topic of considerable interest in the remote-sensing community. These two data sources can provide a diverse set of temporal, spectral, textural and polarimetric features which can be invaluable for cropland classification. However, some optical features or some radar features may have a relatively high correlation with other features. Hence, it seems to be necessary to choose the optimum features in order to reduce the dimensions of the data and to improve cropland classification accuracy. This article proposes a strategic feature selection method from a feature set of bitemporal RapidEye and Uninhabited Aerial Vehicle synthetic aperture radar (UAVSAR) images. The proposed method is designed to select the most relevant features and to remove redundant features based on the two concepts of separability and dependency. The proposed method is therefore referred to as maximum separability and minimum dependency (MSMD). For evaluating efficiency, MSMD and some well-known filter and wrapper feature selection methods are compared using a random forest classifier. Experimental tests confirmed that the classification results obtained from the MSMD feature selection method were more accurate than those achieved by filter methods. Moreover, they had an accuracy comparable to that of the results from the wrapper method. Furthermore, with regard to running time, MSMD operated as fast as the filter methods. It had a straightforward structure compared to the wrapper method, and as a result was faster than this method.

Acknowledgements

The authors would like to present their acknowledgments to the JPL NASA, the SMAPVEX 2012 team, and the Agriculture and Agri-Food for providing for the PolSAR and the optical data used in this research.

Disclosure statement

No potential conflict of interest was reported by the authors.