Modeling and analysis of optical test of digital camera based on orthoperspective theory

Abstract

Digital camera is a very effective equipment of untouched optical test in large-visual imagines collection. However, it also has some differences between camera optical system and perspective projection. So it causes different extent of nonlinearity-optical distortion between theory imagines and actual imagines which projected on imagine plane of camera. It's necessary to rectify imagine distortion to improve veracity of imagine test and mode matching. Orthographic projection, weak perspective and paraperspective projection were major researched models in most of former theses. The former models ignore two important indexes of object and the last model has a theory problem about an angle of incidence. Comparing with theory imagines, the actual imagines of three models have large distortion. This paper brings forward a new model which based on orthoperspective model. First, revolving the light axes till it perpendicular to a plane of centroid. Second, we draw projection curves which based on orthographic projection theory. This model proves the main factors of orthoperspective distortion are revolving angle and camera foci. This model both takes fully use of object indexes and has solved problem about incidence angle. By numerical simulation and experiment, in most of measurement orthoperspective model has least imagine distortion and projection closest to theory imagine. If an object has average density and some height, taking this model can enhance measure precision.