Semi-automatic extraction of digital surface model using ALOS/PRISM data with ENVI

Forest canopy height is an important indicator of standing biomass for management purposes as well as for the assessment of carbon storage. Theoretically, photogrammetry is one of remote sensing technologies which can be used to extract forest canopy height information. The Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM) carried by the Advanced Land-Observing Satellite was designed to generate worldwide topographic data with its high-resolution and stereoscopic observation. A semi-automatic method for the extraction of digital surface model using PRISM data with ENVI is introduced. Tie points scattered evenly over the common area are manually selected on the stereo-image pair. Their ground coordinates are calculated using the geocoding parameters delivered along with the nadir image. Their elevations are extracted from SRTM by their ground coordinates. Ground control points (GCP) files needed in the stereo-processing of PRISM data can be composed by the image coordinates, ground coordinates and elevations. With the prepared tie points and GCP files, PRISM data can be stereo-processed automatically by ENVI. The results showed that the elevation from PRISM DSM is highly correlated with that from GLAS data and forest canopy height information is explicitly exhibited on it.