The Performance of Random Forests in an Operational Setting for Large Area Sclerophyll Forest Classification

Remote Sens. 2013, 5(6), 2838-2856; doi:10.3390/rs5062838

Author

Andrew Mellor ^1,2,3,* , Andrew Haywood ^2,3

, Christine Stone ⁴

 and Simon Jones ¹

¹

School of Mathematical and Geospatial Sciences, RMIT University, GPO Box 2476, Melbourne, VIC 3001, Australia

²

Victorian Department of Environment and Primary Industries, 8 Nicholson Street, East Melbourne, VIC 3002, Australia

³

Joint Remote Sensing Research Program, School of Geography, Planning and Environmental Management, University of Queensland, St Lucia, QLD 4072, Australia

⁴

New South Wales Department of Primary Industries, P.O. Box 100, Beecroft, NSW 2119, Australia

^*

Author to whom correspondence should be addressed. 

Received: 17 April 2013 / Revised: 10 May 2013 / Accepted: 25 May 2013 / Published: 4 June 2013

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Abstract 

Mapping and monitoring forest extent is a common requirement of regional forest inventories and public land natural resource management, including in Australia. The state of Victoria, Australia, has approximately 7.2 million hectares of mostly forested public land, comprising ecosystems that present a diverse range of forest structures, composition and condition. In this paper, we evaluate the performance of the Random Forest (RF) classifier, an ensemble learning algorithm that has recently shown promise using multi-spectral satellite sensor imagery for large area feature classification. The RF algorithm was applied using selected Landsat Thematic Mapper (TM) imagery metrics and auxiliary terrain and climatic variables, while the reference data was manually extracted from systematically distributed plots of sample aerial photography and used for training (75%) and accuracy (25%) assessment. The RF algorithm yielded an overall accuracy of 96% and a Kappa statistic of 0.91 (confidence interval (CI) 0.909–0.919) for the forest/non-forest classification model, given a Kappa maximised binary threshold value of 0.5. The area under the receiver operating characteristic plot produced a score of 0.91, also indicating high model performance. The framework described in this study contributes to the operational deployment of a robust, but affordable, program, able to collate and process large volumes of multi-sourced data using open-source software for the production of consistent and accurate forest cover maps across the full spectrum of Victorian sclerophyll forest types. View Full-Text

Keywords: large area monitoring;  forest extent;  random forests;  operational;  Landsat TM;  MODIS

This is an open access article distributed under the Creative Commons Attribution License (CC BY 3.0).

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