Recently orthophoto has been spreading in public, as the rectifying processes become easier under the development of digital photogrammetric workstation. Though it might be seemed familiar for public as the images are just like real, but some professional knowledge of photogrammetry are required to make interpretation relevant.
This paper discusses geometric characteristics such as distortion and accuracy of large scale orthophotos. And these characteristics are analyzed as (1) distortion by height, (2) remaining distortion caused by central projection, (3) miss recognition without stereo view and (4) limitation of recognition of aerial photos. In this experiment, 30% of road is occluded and houses are misinterpreted by (1) low contrast, (2) low image quality, (3) surrounding trees and (4) structure misunderstood easily. And six instructions are presented to improve interpretation for houses. As the result, misinterpretation of houses on orthophotos is reduced from 25% to 9%. and become close to stereo interpretation.
