Land cover change detection using Landsat imagery - comparison of three methods

Abstract

Environmental changes are amongst the most important research subjects in geography. The changes may be natural, but also may be caused by human activity. Land cover is a significant component of the changing environment. Monitoring of its changes involves usage of satellite techniques. Landsat mission provides comparable data since forty years, very useful in land cover studies. Utilization of satellite techniques in such researches is developing quickly. This paper is an example of methods that enable quick and quite accurate assessment of range and spatial distribution of land cover changes. Practical application of image difference, principal component analysis and supervised classification to detect land cover changes is presented. Methods are applied to study area containing different land cover classes. Accuracy of methods was tested and compared. Combining methods presented in earlier researches, five new methods were developed: image difference, image difference with classification, classification, principal component analysis, principal component analysis with classification. Methods were applied to three different input datasets: pairs of images with different level of preprocessing. First dataset was a pair of georeferenced Landsat Thematic Mapper images. The second dataset was the same pair of images, atmospherically corrected using dark object subtraction method. Normalization of one image to the other provided the third dataset. Accuracy assessment was executed. Results were obtained from confusion matrices. Overall accuracy of methods was high, from 77% to 91%. Supervised classification was the most accurate method. Combining fully automatic methods with supervised classification has increased overall accuracy of automatic change detection, however not significantly. Studies on combining change detection methods should be continued. Future studies should concentrate on the automation of change detection process