In this paper, an algorithm of automatic mosaic of facade texture from vehicle-based close-ranged image sequence is presented. Close-ranged DC images have nonlinear distortion due to the large obliquity of the posture of DC and obvious lens distortion, so it needs to be implemented that the preprocessing of automatic rectification of images, Occlusion removal and elimination of lens distortion. As close-ranged imagery as concerned, the facade is too large to be covered by a single image. Therefore, image mosaic is indispensable to acquire whole facade texture. Two mosaic methods are presented in this paper.
1) Selecting mosaic point pair. After the preprocessing, only the displacements in X-axis and Y-axis respectively are needed to determine in mosaic process because facade textures are all rectified onto plumb plane. Therefore the strategy combined with correlation coefficient and geometric constraint is employed to acquire mosaic point pair by which the displacements are determined. This method cannot be applicable when the imagery is taken too close to the facade (< 50m), because the geometric distortion cannot be eliminated perfectly after the rectification process.
2) Strip method. It is deduced to determine the relatively spatial relationship of the images facade texture involved that a model of least square adjustment, similar to the strip block adjustment, based on the formula of the projection of image point on the projective plane with the DC angular parameters determined early as weighted observation. Then a method similar to generating ortho-image is employed to generate the whole facade texture. This method is proved to be more applicable.