Comparison of Canopy Height Models Derived from Srtm/ned and Nextmap® Usa Elevation Data

Vegetation canopy height is one of the fundamental structural parameters for estimating forest biomass and evaluating forest carbon balance. Remote sensing technologies like interferometric synthetic aperture radar (abbreviated as IFSAR or IFSAR) may provide a means to extract vegetation canopy heights remotely. A comparison of canopy height estimates derived from IFSAR scattering phase center height (hspc) and a newly proposed method to derive canopy height model (CHM) using the IFSAR elevation data is presented for shrub/scrub and evergreen forest vegetation classes and various terrain slopes ranging between 0 30 for two study sites in Minnesota, USA. The X-HH IFSAR hspc was derived from the subtraction of the NEXTMap® USA digital terrain model (DTM) from the NEXTMap® digital surface model (DSM). The C-HH IFSAR hspc was derived from the subtraction of the National Elevation Data (NED) from the NASA-JPL Shuttle Radar Topography Mission (SRTM) first surface elevation dataset. The Xand C-band-derived hspc were compared against in-situ measured tree heights. Both hspc models underestimated the canopy height with an overall 5.4 m root mean square error (RMSE) and 8.9 m for the NEXTMap® and SRTM-NED data, respectively. The CHM derived NEXTMap® and the SRTM/NED CHMs compared to the in-situ measurements for vegetation of heights greater than 10 m received an overall accuracy of 2.18 m RMSE and 3.41 m RMSE, respectively.