Accuracy Investigation on Orthophotos Produced from Digital Aerial Imagery Recorded from Different Altitudes

A digital orthophoto is a topographic image that has a fixed scale like a map and on which values such as coordinates and lengths can be read, which is obtained by eliminating the errors caused by tilts and rotations in aerial images and minimizing the point shifts caused by height differences in the terrain. Digital orthophotos offer more flexible, cost-effective, and higher-quality outputs than classical methods. There is no decrease in the quality of the image as in the analog technique, and it can also be presented quickly and easily in the digital environment. The geometrical accuracy of orthophoto maps used in geomatics applications is of even greater importance. This study compared the orthophoto maps, that have a fixed scale like maps, obtained from digital aerial photographs at a ground sample distance of 7, 15 and 25 cm in 2011 in the campus area of Aksaray University, in terms of their positional accuracy. Orthophoto mosaic images were created using “Erdas LPS” software. When the accuracy are compared, it was found that digital orthophoto maps produced at three different ground sample distances gave us similar results for standard techniques. It was also concluded that the positional accuracy of orthophoto maps for all three ground sample distances was suitable for use as reference and as a base in all application areas, except for those requiring very high accuracy.