Optimal Scenario Development and Sensitivity Analysis Methodology for Multi-Standard Geospatial Positional Accuracy Testing in Varied Topography: Evidence from Ethiopian Case Studies

Ethiopia uses photogrammetry for land registration and planning, but in-situ calibration is required due to factors affecting geometric accuracy. This study aimed to develop optimal scenarios and a sensitivity analysis framework for multi-standard geospatial positional accuracy testing of photogrammetric-derived orthophotos across varied topographies in Ethiopia. GNSS static measurements, considered true positions, were used to evaluate orthophoto accuracy, and the data were least-squares adjusted using Leica Geo-Office. Three scenarios were designed based on the number of checkpoints (CPs), 10, 15, and 20, considering both the number and spatial distribution of CPs across three cities with diverse topography. Scenario development and sensitivity analysis were guided by multi-standard principles. Results showed that positional accuracy was not highly sensitive to variations in CP numbers or distribution. Specifically, the combined RMSE in easting and northing for 10, 15, and 20 CPs were ± 36, ±40, and ± 32; ±38, ± 40, and ± 33; and ± 39, ±40, and ± 35 cm in Bahir Dar, Harer, and Debre Markos, respectively. Coordinate differences between orthophotos and GNSS measurements appeared as systematic shifts rather than random errors. While increasing CP from 10 to 20 slightly reduced RMSE deviations among scenarios and case studies, achieving optimal accuracy depended more on selecting representative CP locations, such as sharp or visible corners of manmade features, and accounting for topographic variations. Overall, sensitivity analysis combined with multi-standard approaches provides a robust and practical framework for assessing positional accuracy, ensuring that photogrammetric-derived geospatial data are reliable and suitable for planning, development, and mapping applications across diverse terrains.