GENERATING ORTHOIMAGES FOR CLOSE-RANGE OBJECTS BY AUTOMATICALLY DETECTING BREAKLINES

Close-range objects (industrial, architectural etc) are highly character- ized by abrupt changes of their surface continuity. Thus no DEM (and thus orthoimage) of high quality can be generated unless these discon- tinuities are taken into account. Fortunately, these breaklines are mostly straight lines, and thus their automatic detection is not very dif- ficult. Besides, their detection can also lead to information about the orientation of the images, easing down the necessity for excessive con- trol points. This paper focuses in how these useful graphical elements (breaklines) can be detected and extracted in a way that the user's intervention will be minimum. The developed algorithm extracts straight-line breaklines from a stereo model and through a matching process between all break- lines' endpoints, a 3D object model is constructed.