Spaceborne Interferometric SAR (InSAR) technology used in the Shuttle Radar Topography Mission (SRTM) and spaceborne lidar such
as Shuttle Laser Altimeter-02 (SLA-02) are two promising technologies for providing global scale digital elevation models (DEMs). Each
type of these systems has limitations that affect the accuracy or extent of coverage. These systems are complementary in developing DEM
data. In this study, surface height measured independently by SRTM and SLA-02 was cross-validated. SLA data was first verified by field
observations, and examinations of individual lidar waveforms. The geolocation accuracy of the SLA height data sets was examined by
checking the correlation between the SLA surface height with SRTM height at 90 m resolution, while shifting the SLA ground track within
its specified horizontal errors. It was found that the heights from the two instruments were highly correlated along the SLA ground track, and
shifting the positions did not improve the correlation significantly. Absolute surface heights from SRTM and SLA referenced to the same
horizontal and vertical datum (World Geodetic System (WGS) 84 Ellipsoid) were compared. The effects of forest cover and surface slope on
the height difference were also examined. After removing the forest effect on SRTM height, the mean height difference with SLA-02 was
near zero. It can be further inferred from the standard deviation of the height differences that the absolute accuracy of SRTM height at low
vegetation area is better than the SRTM mission specifications (16 m). The SRTM height bias caused by forest cover needs to be further
examined using future spaceborne lidar (e.g. GLAS) data.