Comparison between WorldView-2 and SPOT-5 images in mapping the bracken fern using the random forest algorithm

John O. Odindi; Elhadi E. Adam; Zinhle Ngubane; Onisimo Mutanga; Rob Slotow

doi:10.1117/1.JRS.8.083527

6 November 2014 Comparison between WorldView-2 and SPOT-5 images in mapping the bracken fern using the random forest algorithm

John O. Odindi, Elhadi E. Adam, Zinhle Ngubane, Onisimo Mutanga, Rob Slotow

Author Affiliations +

Journal of Applied Remote Sensing, Vol. 8, Issue 1, 083527 (November 2014). https://doi.org/10.1117/1.JRS.8.083527

Abstract

Plant species invasion is known to be a major threat to socioeconomic and ecological systems. Due to high cost and limited extents of urban green spaces, high mapping accuracy is necessary to optimize the management of such spaces. We compare the performance of the new-generation WorldView-2 (WV-2) and SPOT-5 images in mapping the bracken fern [Pteridium aquilinum (L) kuhn] in a conserved urban landscape. Using the random forest algorithm, grid-search approaches based on out-of-bag estimate error were used to determine the optimal ntree and mtry combinations. The variable importance and backward feature elimination techniques were further used to determine the influence of the image bands on mapping accuracy. Additionally, the value of the commonly used vegetation indices in enhancing the classification accuracy was tested on the better performing image data. Results show that the performance of the new WV-2 bands was better than that of the traditional bands. Overall classification accuracies of 84.72 and 72.22% were achieved for the WV-2 and SPOT images, respectively. Use of selected indices from the WV-2 bands increased the overall classification accuracy to 91.67%. The findings in this study show the suitability of the new generation in mapping the bracken fern within the often vulnerable urban natural vegetation cover types.

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John O. Odindi, Elhadi E. Adam, Zinhle Ngubane, Onisimo Mutanga, and Rob Slotow "Comparison between WorldView-2 and SPOT-5 images in mapping the bracken fern using the random forest algorithm," Journal of Applied Remote Sensing 8(1), 083527 (6 November 2014). https://doi.org/10.1117/1.JRS.8.083527

Published: 6 November 2014

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