研究目的

The objective of this study is to assess the efficacy of using SfM-MVS for capturing forest structure in three mangrove sites with differing structural characteristics. Given applications of SfM-MVS have been mainly conducted in forestry plantations characterized by tree stands of regular height and spacing, we were interested to see how this method would perform in mangroves, which have more peculiar growth form. Comparisons of point cloud utility is made between SfM-MVS and TLS, and canopy height models (CHMs) are generated to estimate forest volume as a proxy for AGB.

研究成果

This study compared the ability of SfM-MVS and TLS to capture forest structure and volume in three mangrove sites of differing structural characteristics. SfM-MVS was unable to capture points below the canopy in the same detail offered by TLS, which was clearly superior in terms of point density. For forest volume, SfM-MVS captured the top of the canopy more accurately than the TLS, which suffered from occlusion, however, it tends to overestimate volume in canopy gaps. The choice between either SfM-MVS and TLS depends on the accuracy, spatial scale, and time scale required, with both offering potential advantages and disadvantages.

研究不足

Horizontal misalignments between the TLS and SfM-MVS raster models were noted, greatest in the juvenile and mixed sites. The DTM created interpolated elevation heights taken at the peripheries of each site, as the RTK-GNSS could not obtain a signal below the canopy. The surface differencing method assumes a constant volume below the height of the CHM, which may not account for species-specific wood density and growth forms.