What method is used to determine the horizontal accuracy of an ortho-rectified aerial image?

The method used to determine the horizontal accuracy of an ortho-rectified aerial image involves surveying photo-identifiable field points and evaluating them through statistical analysis, specifically using Root Mean Square Error (RMSE).

When ortho-rectifying an aerial image, it is essential to ensure that the image accurately represents true geographical locations. To accomplish this, identifiable points on the aerial image—which can be recognized on the ground, such as intersections, building corners, or other distinct landmarks—are accurately surveyed in the field. These surveyed coordinates, known for their exactness, are then compared with the corresponding coordinates obtained from the ortho-rectified image.

The RMSE is a common statistical measure used in this context, as it quantifies the difference between the surveyed points and their corresponding locations in the ortho-rectified image. A lower RMSE value indicates higher accuracy in the image’s representation of geographic locations, thus confirming the integrity of the ortho-rectification process. This method is crucial because it provides a quantitative assessment of the image’s accuracy, which is critical for applications in geospatial analysis, mapping, and various GIS applications.