Exploring Subpixel Learning Algorithms for Estimating Global Land Cover Fractions from Satellite Data Using High Performance Computing

Remote Sensing

Kumar S Raja¹  Shreekant Gayaka²  Subodh Kalia²  Sangram Ganguly³  Shuang Li³  Andrew Michaelis³  Petr Votava³  Uttam Kumar³  Ramakrishna R. Nemani³  Cristina Milesi³  Weile Wang³  Hirofumi Hashimoto³  Ruchita Sinha⁴ 

[1] Airbus Engineering Centre India, Whitefield Road, Bangalore 560048, India;Bay Area Environmental Research Institute (BAERI), Sonoma, CA 95476, USA;NASA Ames Research Center, Moffett Field, CA 94035, USA;VISA INC., 800 Metro Center Blvd, Foster City, CA 94404, USA;

关键词: machine learning;    subpixel classification;    Landsat;    WELD;    mixed pixel;    global endmembers;    land cover;    high performance computing;    nighttime lights;   

DOI  :  10.3390/rs9111105

来源: DOAJ

【 摘 要 】

Land cover (LC) refers to the physical and biological cover present over the Earth’s surface in terms of the natural environment such as vegetation, water, bare soil, etc. Most LC features occur at finer spatial scales compared to the resolution of primary remote sensing satellites. Therefore, observed data are a mixture of spectral signatures of two or more LC features resulting in mixed pixels. One solution to the mixed pixel problem is the use of subpixel learning algorithms to disintegrate the pixel spectrum into its constituent spectra. Despite the popularity and existing research conducted on the topic, the most appropriate approach is still under debate. As an attempt to address this question, we compared the performance of several subpixel learning algorithms based on least squares, sparse regression, signal–subspace and geometrical methods. Analysis of the results obtained through computer-simulated and Landsat data indicated that fully constrained least squares (FCLS) outperformed the other techniques. Further, FCLS was used to unmix global Web-Enabled Landsat Data to obtain abundances of substrate (S), vegetation (V) and dark object (D) classes. Due to the sheer nature of data and computational needs, we leveraged the NASA Earth Exchange (NEX) high-performance computing architecture to optimize and scale our algorithm for large-scale processing. Subsequently, the S-V-D abundance maps were characterized into four classes, namely forest, farmland, water and urban areas (in conjunction with nighttime lights data) over California, USA using a random forest classifier. Validation of these LC maps with the National Land Cover Database 2011 products and North American Forest Dynamics static forest map shows a 6% improvement in unmixing-based classification relative to per-pixel classification. As such, abundance maps continue to offer a useful alternative to high-spatial-resolution classified maps for forest inventory analysis, multi-class mapping, multi-temporal trend analysis, etc.

【 授权许可】

Unknown