The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part BI. Beijing 2008 
to obtain accurate EO parameters of images is by automatic 
triangulation (AT). However, most commercial AT software 
cannot handle oblique images because of the nature of oblique 
images. A least squares method is proposed in this paper. In the 
proposed method, the differences between edges of the building 
façade extracted from the oblique image and the corresponding 
Figure 7. Projected building boundary on oblique image 
projected boundaries are used to estimate the corrections of EO 
parameters. The differences of x and y coordinates of end points 
of edges are used as observations given in formula (1) and the 
corrections of EO parameters are treated as unknowns. 
Ax,- = x,- - x,- 
Ay t =yi-y'i 
(i) 
where: X,-, y t = coordinates of i‘ h end point on oblique image 
X,-, y j = coordinates of corresponding projected end point. 
The EO parameters from GPS/IMU are used as approximate 
values and their corréctions are computed by the least squares 
adjustment. Once the accurate EO parameters of the image are 
computed, the right image portion can be determined by 
projecting the building façade onto the oblique image with the 
corrected EO parameters and added to the 3D building model. 
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4. SUMMERY 
In this paper, Pictometry's proprietary digital imaging system is 
introduced briefly and some issues in 3D city modeling using 
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