| Summary: | Background and Objectives: The recent use of Structure-from-Motion with Multi-View Stereo photogrammetry (SfM-MVS) in forestry has underscored its robustness in tree mensuration. This study evaluated the differences in tree metrics resulting from various related SfM-MVS photogrammetric image acquisition scenarios. Materials and Methods: Scaled tri-dimensional models of 30 savanna trees belonging to five species were built from photographs acquired in a factorial design with shooting distance (<i>d</i> = 1, 2, 3, 4 and 5 m away from tree) and angular shift (<i>α</i> = 15°, 30°, 45° and 60°; nested in <i>d</i>). Tree stem circumference at 1.3 m and bole volume were estimated using models resulting from each of the 20 scenarios/tree. Mean absolute percent error (MAPE) was computed for both metrics in order to compare the performance of each scenario in relation to reference data collected using a measuring tape. Results: An assessment of the effect of species identity (<i>s</i>), shooting distance and angular shift showed that photographic point cloud density was dependent on <i>α</i> and <i>s</i>, and optimal for 15° and 30°. MAPEs calculated on stem circumferences and volumes significantly differed with <i>d</i> and <i>α</i>, respectively. There was a significant interaction between <i>α</i> and <i>s</i> for both circumference and volume MAPEs, which varied widely (1.6 ± 0.4%−20.8 ± 23.7% and 2.0 ± 0.6%−36.5 ± 48.7% respectively), and were consistently lower for smaller values of <i>d</i> and <i>α</i>. Conclusion: The accuracy of photogrammetric estimation of individual tree attributes depended on image-capture approach. Acquiring images 2 m away and with 30° intervals around trees produced reliable estimates of stem circumference and bole volume. Research Highlights: This study indicates that the accuracy of photogrammetric estimations of individual tree attributes is species-dependent. Camera positions in relation to the subject substantially influence the level of uncertainty in measurements.
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