CIPA 2003 XIX th International Symposium, 30 September - 04 October, 2003, Antalya, Turkey 
The basic idea of Zitnick and Kanade (2000) is a cooperation 
between support and inhibition. Inhibition enforces the 
uniqueness of a match. Assuming opaque and diffuse- 
reflecting surfaces, a ray of view emanating from a camera will 
hit the scene at one point only. The idea is to gradually weight 
down all matches on a ray besides the strongest. Support is 
realized by filtering the 3D array by a 3D box filter. By this 
means all matching scores corroborate locally to generate a 
continuous surface. We have improved this scheme with 
different means, most notably a combination of image and 
disparity gradient to avoid smoothing away details and a 
detailed treatment of occlusions. Additionally, we use the 
information of a third image by projecting the results of the 
cooperative computation into the third image by means of the 
trifocal tensor and by modification of the 3D array based on 
the correlation score of the first and the third image. 
Figure 7 gives the result for the computation of the disparity 
map from three images of the image sequence given above. 
The disparity map outlines the important structures of the 
scene. While moving from left to right as done in the first two 
visualizations results into the movement of the wall in front of 
the camera and an attractive view, a movement upwards as in 
the rightmost image shows problems from non-modeled 
occlusions. 
4.4 Analysis of the Automatic Approach 
We have shown a way to fully automatically generate metric 
3D structure from the weak information of the perspective 
images of a sequence. Yet, there is ample room for 
improvement before this approach will become practically 
relevant. Most notably, it is necessary to link the results for 
structure computation in two or three images, to obtain a 
coherent result for the sequence. Then, there is a host of 
robustness issues which has to be solved before all types of 
sequences can be handled reliably. Finally, in the foreseeable 
future, the automatic approach will have problems, when the 
perspective skew between images is too large, i.e., when the 
angle between consecutive images is too large. This can be 
avoided by taking more images. This is disadvantageous when 
taking the images, but it helps to avoid a lot of manual work. 
5. CONCLUDING REMARKS 
Image-based survey and 3D modeling of architectural objects 
can be performed by photogrammetric as well as computer 
vision and computer graphics methods. The latter allow fully 
automatic feature extraction, orientation, and 3D object 
reconstruction, even if the knowledge about the geometry of 
the image sequence is weak. Auto-calibration is possible in 
case that the interior orientation data have changed during the 
image recording (focusing, zoom) or are not available at all. 
Preferably, photogrammetric and computer vision methods are 
integrated to generate virtual models from images as precise 
and reliable as required. 
It should be noted that the results presented in this paper are 
preliminary. The reconstruction and modeling of Wartburg 
Castle is still in progress. 
6. REFERENCES 
Daskalopoulos, A., Georgopoulos, A., Ioannidis, Ch., Makris, 
G.N., 2003. A Trip from Object to Image and Back. The 
International Archives of the Photogrammetry, Remote 
Sensing and Spatial Information Sciences, Ancona / Italy, Vol. 
XXXIV (5/W12), pp. 141-144. 
El-Hakim, S.F., 2002. Semi-Automatic 3D Reconstruction of 
Occluded and Unmarked Surfaces from Widely Separated 
Views. The International Archives of the Photogrammetry, 
Remote Sensing and Spatial Information Sciences, Corfu / 
Greece, Vol. XXXIV (5), pp. 143-148. 
Fischler, M., Bolles, R., 1981. Random Sample Consensus: A 
Paradigm for Model Fitting with Applications to Image 
Analysis and Automated Cartography. Communications of the 
ACM, 24 (6), pp. 381-395. 
Freeh, I., Koch, B., 2003. Multimedia Geoinformation in Rural 
Areas with Eco-Tourism: The ReGeo-System. In: Information 
and Communication Technologies in Tourism 2003, Springer, 
Vienna / New York, pp. 421 -429. 
Hanke, K., Oberschneider, M., 2002. The Medieval Fortress 
Kufstein, Austria - An Example for the Restitution and 
Visualization of Cultural Heritage. The International Archives 
of the Photogrammetry, Remote Sensing and Spatial 
Information Sciences, Corfu / Greece, Vol. XXXIV (5), pp. 
530-533. 
Hao, X., Mayer, H., 2003. Orientation and Auto-Calibration of 
Image Triplets and Sequences. The International Archives of 
the Photogrammetry, Remote Sensing and Spatial Information 
Sciences, Munich / Germany, Vol. XXXIV (3/W8). 
Hartley, R., Zisserman, A., 2000. Multiple View Geometry in 
Computer Vision. Cambridge University Press, Cambridge, 
UK. 
Mayer, H., 2003. Analysis of Means to Improve Cooperative 
Disparity Estimation. The International Archives of the 
Photogrammetry, Remote Sensing and Spatial Information 
Sciences, Munich / Germany, Vol. XXXIV (3/W8). 
Pollefeys, M., Verbiest, F., van Gool, L., 2002. Surviving 
Dominant Planes in Uncalibrated Structure and Motion 
Recovery. In; Seventh European Conference on Computer 
Vision, Vol. II, pp. 837-851. 
Pollefeys, M., van Gool, L., Vergauwen, M., Cornelis, K., 
Verbiest, F., Tops, J., 2003. 3D Capture of Archaeology and 
Architecture with a Hand-Held Camera. The International 
Archives of the Photogrammetry, Remote Sensing and Spatial 
Information Sciences, Ancona / Italy, Vol. XXXIV (5/W12), 
pp. 262-267. 
Zitnick, C., Kanade, T., 2000. A Cooperative Algorithm for 
Stereo Matching and Occlusion Detection. IEEE Transactions 
on Pattern Analysis and Machine Intelligence, 22 (7), pp. 675- 
684. 
108