Systematic Evaluation of the Influence of Camera Placement and Settings on the Quality of Photogrammetric Models of Rocks

Despite the widespread adoption of photogrammetry across diverse disciplines, the relative influences of image acquisition parameters on the quality of photogrammetric models are seldom quantitatively understood. To address this, we conducted experiments under controlled lighting conditions, camera positions, and camera settings and evaluated the quality of the resultant models using both a subjective rating and a quantitative comparison. In total, 2541 models were evaluated in this study. In general, higher quality models can be produced by minimising large changes in the direction of view between adjacent images. Strong digital noise due to high ISO is detrimental to model quality, although this may be partially mitigated by noise reduction post-processing. RAW images generally produce higher quality models than JPEG images; however, at high ISOs, RAW images may result in poorer quality models due to their inherent lack of pre-applied noise reduction. Images taken with a smartphone produced models of comparable quality to those taken with a dedicated camera. Models were not consistently reproducible, even with near-identical images; therefore, practitioners must be aware of their margins of error when interpreting photogrammetric results. This study therefore provides practical guidance for practitioners based on a robust parameter study using natural geological samples.