Dean John Townshend article published in the International Journal of Digital Earth, "Global Characterization and Monitoring of Forest Cover Using Landsat Data: Opportunities and Challenges."
In August 2012, John Townshend, Dean of the College of Behavioral and Social Sciences, and several Maryland colleagues – Jeffrey Masek, Chengquan Huang, Eric Vermote, Feng Gao, Saurabh Channan, Joseph Sexton, Min Feng, Ramghuram Narasimhan, Dohyung Kim, Kuan Song, Danxia Song, Xiao-Peng Song, Praveen Noojipady, Bin Tan, Matthew Hansen, Mengxue Li & Robert Wolfe – were published in the International Journal of Digital Earth.
The compilation of global Landsat data-sets and the ever-lowering costs of computing now make it feasible to monitor the Earth’s land cover at Landsat resolutions of 30 m. In this article, we describe the methods to create global products of forest cover and cover change at Landsat resolutions. Nevertheless, there are many challenges in ensuring the creation of high-quality products. And we propose various ways in which the challenges can be overcome. Among the challenges are the need for atmospheric correction, incorrect calibration coefficients in some of the data-sets, the different phenologies between compilations, the need for terrain correction, the lack of consistent reference data for training and accuracy assessment, and the need for highly automated characterization and change detection. We propose and evaluate the creation and use of surface reflectance products, improved selection of scenes to reduce phenological differences, terrain illumination correction, automated training selection, and the use of information extraction procedures robust to errors in training data along with several other issues. At several stages, we use Moderate Resolution Spectro-radiometer data and products to assist our analysis. A global working prototype product of forest cover and forest cover change is included.