Abstract
This paper characterizes the body of knowledge on remote sensing from 1999 to 2021 by employing bibliometric techniques based on the Science Citation Index databases and the Social Science Citation Index of the Web of Science, abbreviated to “SCI” and “SSCI”, respectively. A total of 28,438 articles were analyzed from various aspects of the publication characteristics, such as countries, institutes, subjects, journals, and keywords. Dynamic changes in published remote sensing research were examined by segregating the 19-year period into 4 stages. Co-occurrences of keywords from three aspects were evaluated, including technology, methodology, and applications. Results show that “hyperspectral remote sensing”, “classification”, “monitoring” and “MODIS” in the category of technology have emerged more frequently in recent years, and there are strong co-occurrences of “remote sensing” and “GIS” in the remote sensing technology category. In addition, there was a marked shift from traditional analytical methods (i.e., geostatistics and neural networks) to a variety of emerging methods, such as support vector machines, random forests, and feature extraction. Moreover, research hotspots are identified for remote sensing applications, which have expanded significantly with improvements in technology and methodology. In particular, “water quality”, “climate change”, and “urbanization” have become popular themes in recent years. Finally, future directions of remote sensing are identified, which would be beneficial for researchers and policy makers.