I am working on estimating Canopy height of mangrove. I want to employ ASTER level 1A or 1B data to generate Digital Surface Model (DSM). But after I searched it in Google, I cannot find an existed method to generate a DSM. So, how do I generate a DSM using ASTER level 1A/B data? Or, can the ASTER data (level 3 DEM) set be considered as a digital surface model (DSM) which provides heights of the surface objects?
Discussion: After thinking for a while, I understand ASTER has theer subsystems: VNIR (visible and Inferred band), SWIR and TIR. The VNIR has the 3N and 3B band which can be applied to generate DEM. Moreover, DSM is a subset of DEM. Since the channels cannot penetrate canopy to reflect ground, the level 1 data of ASTER indicates the surface height information instead ground information. Thus, the raw data can generate digital surface model.