Characterization of ASTER GDEM elevation data over vegetated area compared with lidar data

Abstract

Current researches based on areal or spaceborne stereo images with very high resolutions (<1 m) have demonstrated that it is possible to derive vegetation height from stereo images. The second version of the Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model (ASTER GDEM) is the state-of-the-art global elevation data-set developed by stereo images. However, the resolution of ASTER stereo images (15 m) is much coarser than areal stereo images, and the ASTER GDEM is compiled products from stereo images acquired over 10 years. The forest disturbances as well as forest growth are inevitable in 10 years time span. In this study, the features of ASTER GDEM over vegetated areas under both flat and mountainous conditions were investigated by comparisons with lidar data. The factors possibly affecting the extraction of vegetation canopy height considered include (1) co-registration of DEMs; (2) spatial resolution of digital elevation models (DEMs); (3) spatial vegetation structure; and (4) terrain slope. The results show that the accurate coregistration between ASTER GDEM and national elevation dataset (NED) is necessary over mountainous areas. The correlation between ASTER GDEM minus NED and vegetation canopy height is improved from 0.328 to 0.43 by degrading resolutions from 1 arc-second to 5 arc-second and further improved to 0.6 if only homogenous vegetated areas were considered.

Keywords:

• vegetation canopy height
• ASTER GDEM
• NED
• photogrammetry
• stereo-mapping

Acknowledgements

This work was partially supported by the National Basic Research Program of China (Grant no.2013CB733404), the National Natural Science Foundation of China (Grant nos. 41001208 and 91125003), support for the study was also provided by the NASA Terrestrial Ecology Program (NNX09AG66G). The LVIS data sets were provided by the Laser Vegetation and Ice Sensor (LVIS) team in the Laser Remote Sensing Laboratory at NASA Goddard Space Flight Center with support from the University of Maryland, College Park. The authors thank each of the foregoing. Special thanks to the ASTER GDEM team and USGS for the open data access.