NASA’s Global Ecosystem Dynamics Investigation (GEDI) is a lidar instrument on the International Space Station that measures forest height, structure and surface topography. We investigate the precision and accuracy of these data by comparing near-coincident GEDI observations and by comparison to data from NASA’s airborne LVIS laser system from forests in the U.S., Central America, and Africa. We also test new methods to improve how GEDI detects the ground beneath trees and relevance to future, potential space missions like NASA’s EDGE.