What describes the overall effects of both tilt and relief on an aerial photo?

An orthophoto is a highly accurate aerial photograph that has been geometrically corrected to ensure that the scale is uniform across the image, and this process accounts for variations in tilt and relief. When creating an orthophoto, both the tilt of the camera and the effects of terrain relief—such as hills or valleys—are corrected, resulting in an image that represents true distances and areas as if it were taken from directly above. This allows for accurate measurements and analysis of the landscape, which is essential in fields like surveying and mapping.

In contrast, a vertical photograph captures an image with the camera pointed straight down, but it may not account for variations in relief, leading to potential inaccuracies in representing the ground features. The principal point refers to the focal point of the camera at the intersection of image and ground, but it does not encompass the corrections for tilt and relief. A radial line is typically associated with the way distances can be measured from a central point, but it is not relevant to the overall effects of tilt and relief on aerial imagery.

Thus, the orthophoto stands out as the correct answer, as it combines both the effects of tilt and relief to create a corrected, accurate aerial representation of the terrain.