Evaluation of Orthophoto Accuracy from Old Aerial Photographs Using Various Image Digitization Techniques

Orthophoto maps are essential for spatial analysis in interpreting land management and topographic studies. However, there have been challenges achieving accurate spatial accuracy for orthophoto generation due to constraints of having the proper image acquisition device. This study, therefore, investigates orthophoto accuracy in part of Ibaraki Prefecture using old aerial photographs with different image acquisition devices—a surveying scanner, low- and high-resolution digital cameras, and low- and high-resolution general-purpose scanners, with and without geometric correction. The validation accuracy results show that the RMSE XY errors achieved by the surveying scanner, high-resolution digital camera, and low- and high-resolution general-purpose scanners with geometric correction were 1.887 m, 1.336 m, 2.024 m, and 1.649 m, respectively. However, orthophotos generated from general-purpose scanners without geometric correction showed higher RMSE XY errors, ranging from 15.589 m to 17.032 m. The findings indicate that high-resolution general-purpose scanners with geometric correction achieved the comparable positional accuracy to surveying scanners. In contrast, general-purpose scanners without geometric correction tend to degrade positional accuracy. This study provides a practical assessment for the suitability of image acquisition device to generate orthophoto maps and highlights the applicability of low-cost scanning devices for orthophoto generation. • Orthophoto positional accuracy from old aerial photographs was systematically evaluated using surveying scanner, digital camera, and general-purpose scanner. • General-purpose scanner with geometric correction achieved the comparable positional accuracy to surveying scanner. • The finding highlights the applicability of low-cost digitization device in producing orthophoto maps.