Investigation of forest height retrieval using SRTM-DEM and ASTER-GDEM

Interferometric SAR (InSAR)data have been used to measure canopy height. Polarimetric interferometric SAR (PolInSAR) data can be used to derive canopy height without using ground surface elevation data. But in most cases, only single polarization InSAR data are available and the elevation of ground surface in the forested areas is needed to get the height of the scattering phase center. On contrary, the elevation of canopy surface is relatively easy to obtain by Stereo imagery. In this study the feasibility of the estimation of forest height using SRTM-DEM and ASTER- GDEM was investigated. The ASTER-GDEM was firstly resampled to the pixel size of SRTM-DEM (3 arc-second) and then was registered to SRTM- DEM using the points selected from their aspect maps. The results showed that the registration is necessary because the geolocation error at east-west direction is about half of the pixel size. The relationship between the forest height and the elevation difference was analyzed. The results showed that the elevation difference between registered ASTER-GDEM and SRTM-DEM is positively correlated with the forest height. Although there are some problems when the terrain is rough, it provides us a way to estimate the height of mature forest in flat terrain.