Dowman, Ian 
  
  
  
Fig. 10: Another example for a texture created using CCD images. 
The results from these tests represent the usability of ATPT in practice as most of the manual work in the processing textures is replaced 
with unsupervised machine computations. The importance of this can be realised as many textures can be processed as batch files in 
the computer background, while the user is absent or is concentrated on a different job. 
6 CONCLUSIONS AND FUTURE ENHANCEMENTS 
This paper showed that complete textures with high geometric quality can be produced automatically using the CCD images captured 
and structured in the way presented in this project. No interactions are required to relate the geometric model to the images; a job which 
is usually done by manual observation of several control points on the images. 
The components of the system including the image acquisition, the TID formation, and the texture creation are designed such that the 
formation of VRMs can be performed fully automatically. There is a large research effort at present to produce the geometric models of 
buildings automatically. Given such a geometric model and the location of the terrestrial stations, the model can be split into individual 
faces, for each of which a texture is created automatically using the ATPT. The only interactive part is the registration of the images, 
the status of which will hopefully be improved through the forthcoming research. 
As far as the method developed in this project is concerned, to facilitate the process in this direction, further developments are required 
in the following areas: 
e Data preparation: 
The time to build up a NFR and to register terrestrial images needs to be significantly reduced. Using aerial photographs can 
greatly improve the speed of NFR creation. However, still there is a large amount of time required to register the terrestrial 
images. Therefore, techniques capable of automatic bundle adjustment of terrestrial images need to be developed. Only in this 
case will the production of VRMs become fully practicable and thus acceptable to the community. 
e Image acquisition unit: 
Although the unit is portable and automatic, there is still room for further developments to make it lighter and faster. A possible 
configuration is to use several CCD cameras, linked to a portable computer, to capture several images at once such that they cover 
a complete panoramic view. The cameras need to have a rigid position to make sure they will have sufficient geometric quality. 
e Implementation procedures: 
The current version of the ATPT is command-based and thus needs a visual front-end to be easier to use. In addition, currently 
only textures for rectangular faces can be processed. Thus, improvements are required to cope with non-rectangular shapes. This 
is usually done using a triangulation technique, ie to triangulate the building face and to produce a texture for each triangle. It 
should be noted that, the triangulation should be recursively continued until all vertices of a triangle fall on a single image so that 
its texture can be produced. 
REFERENCES 
Brenner, C., Haala, N., 1998. Fast production of virtual reality city models. International Archives of Photogrammetry and Remote 
Sensing, 32(4): 77-84. 
Chapman D.P., Deacon, A.T.D., Hamid, A., 1994. HAZMAP: a remote digital measurement system for work in hazardous environ- 
ments. Photogrammetric Record, (14) 83: 747-758. 
Debevec, P.E., 1999. Modelling and rendering architecture from photographs. SIGGRAPH 1999, notes for Course 28. 
El-Hakim, S., Brenner, C., Roth, G., 1998. An approach to creating virtual environments using range and texture. International Archives 
of Photogrammetry and Remote Sensing, Hakodate, 32(5): 331-338 
Huang, Y.D., and Harley, L, 1990. CCD-camera calibration without a control field. International Archives of Photogrammetry and 
Remote Sensing, 28(5): 1028-1034. 
Varshosaz, M., 1997. Building modelling for 3D GIS. MPhil Report, University College London, 126 pages. 
Varshosaz, M., 1999. Visually Realistic Construction of Building Models. PHd. Thesis, University College London, 198 pages. 
  
186 International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B5. Amsterdam 2000. 
  
arc 
AB 
AR 
Ph 
bee 
LE 
Thi 
as : 
In : 
sor 
bec 
me 
by 
me 
lim 
de: 
On 
ad 
col 
col 
thu 
arc 
ph 
Re 
arc 
wi 
1.1 
Al 
ex 
Th