## 5 Conclusions  
This study investigated the capabilities of the newly processed high resolution (HR) multi-angular and multi-spectral MISR data products, Bidirectional Reflectance Factors (BRF) and Rahman-Pinty-Verstraete (RPV) model parameters, to estimate mean tree height and canopy cover for the main South African forest types. To date, regional-scale vegetation structural baseline datasets are lacking in South Africa, and the use of multi-angular data in semi-arid regions has been limited. Figure 10: **(a)** Estimated tree height at 275 m spatial resolution across the MISR-HR (Path 167 Block 113) extent covering the iSimangaliso St-Lucia area (commercial forest plantations and indigenous forest) derived from MISR-HR BRF 36 data channels. The grey areas denote the gaps in the MISR coverage. The red box denotes the area of interest (AOI) for discussion, shown enlarged in letters **(b–d)**. The background color maps represents **(b)** Estimated MISR-HR BRF tree height, **(c)** South African National Land-Cover (LC) map reclassified [84], **(d)** Sub-Saharan African forest tree height, with grey areas which denotes gaps as a result of the \(<\)5 m tree height threshold in the product from [8]. A number of scenarios were tested based on different spectral and angular band combinations, e.g., comparing multi-spectral and multi-angular BRF data channels to multi-spectral nadir only data, single-off nadir viewing multi-spectral data as well as the RPV model parameter data, for combined and individual forest types. For the combined forest types, it can be concluded that multi-spectral and multi-angular data were more effective in the estimation of mean tree height and canopy cover, than multi-spectral data alone. The most improved estimation accuracy amongst the three forest types was obtained in the savanna region for mean tree height. In addition, the RPV model parameters (\(\rho_{0}\), \(k\), \(\Theta\)) results showed somewhat poorer performance than the BRF 36 data channel estimation models, but were nevertheless statistically significant. The results from the new MISR HR products (either the off-nadir information or the RPV parameters) provides some level of confidence in the potential of this freely available multi-angle data towards vegetation structural studies at a regional scale. MISR HR products can provide a useful baseline for long-term monitoring due to the significant amount of data available from MISR; indeed, MISR records extend back to the year 2000, close to two decades. To fully exploit the potential of the HR MISR data, more research is warranted using multi-temporal data to make use of phenology information, 2008). In the estimation of tree height, the gap in the data has shown to be difficult to obtain a continuous high accuracy in tree height estimation. Thus, reducing the data gaps in the MISR products (i.e., multiple orbit data) remains an important future milestone towards continuous wall-to-wall vegetation structural parameter estimations [28]. Furthermore, the use of high-resolution data sets (i.e., synthetic aperture radar data) could help to account for the sub-pixel heterogeneity and improve the structural estimation results in combination the multi-angular data. To date in South(ern) Africa's savanna and indigenous forest, the only up-to-date tree height information is in the form of global products which are not locally calibrated and preclude short vegetation (i.e., below 5 m).