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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B5. Istanbul 2004 
photographic process involved many more pictures than used in 
the Hibben Center experiment. The reasons for this were the 
size and complexity of the structure. First of all, photos were 
taken of the exterior as well as the interior of the structure. 
Also, this application was intended to produce an archival 
quality documentation of the structure for the National Park 
Service, therefore, a higher degree of accuracy and 
representation was desired. 
Two sets of photos were taken of the structure. One set was 
taken for a visual record to accurately document the structure's 
surface. The second set involved the use of targets that would 
allow a more accurate selection of ground points in the 
photogrammetric process. The targets employed were 4 cm 
white circles on a 6 cm square field of black. These were 
carefully placed on the walls of the structure, and then 
successive photos were taken of the walls. The bottom-most 
targets were set at a known height, using a laser level for 
consistency, and the remainder were spaced generally at 4- 
meter intervals, at three different heights (Figure 4). 
  
Figure 4. Front view of the Quarai mission church showing the 
placed targets to be used as ground control points. The 
distortion in this uncorrected image is due to the fish-eye lens. 
As in the Hibben Experiment, the fish-eye lens was able to 
capture the entire height of the walls. Photos could then be 
taken by a photographer using a standard tripod with the camera 
at a general height of 1.4 meters (Figure 3). Photos were taken 
at 3 to 4 meter intervals, depending on the complexity of the 
surface. This distance allowed enough overlap between images 
for the photogrammetric processing. Most images were taken 
at a distance of 7.8 meters from the subject. This distance was 
determined to be ideal in this case, as the camera and lens could 
capture the entire height of the walls. This was one of the 
advantages of using the fish-eye lens, as in most of the interior 
of the church, the walls were only 8-8.5 meters apart. 
The images were then downloaded and processed in the 
PhotoModeler software. The same process was used as for the 
Hibben Center experiment, but in this case, the photos 
containing the placed targets were used to tie the pictures 
together. Once the model was built, the photos of the monument 
that did not contain the targets was then used to paint the 
surface of the virtual model. 
4. RESULTS AND CONCLUSION 
The mission church, La Purísima Concepción, in the Quarai 
complex at Salinas National Monument proved to be an ideal 
subject for experimenting with digital photogrammetric 
techniques for documentation of the cultural heritage. The final 
results also provide an archival quality record for the park 
officials managing the site. The resulting digital models provide 
detailed documentation, measurements, and maps that could be 
used for other research and restoration projects. The virtual 
three-dimensional model provides a digital document for the 
park service's records and offers opportunities for educating the 
general public. 
Digital photogrammetric recording of archaeological features 
can provide accurate, non-destructive documentation of 
important sites subject to destruction, environmental change, 
and decay. This experiment has shown that accurate 
measurements and maps can be generated from this process and 
that these products can be utilized in other on-going projects. 
In addition, accurate depictions of the walls and structures are 
recorded digitally for archival purposes. Furthermore, this 
process is relatively inexpensive compared to use of laser 
technologies, making it a viable option for cultural site 
managers with restricted funds. 
5. ACKNOWLEDGEMENTS 
We would like to acknowledge the National Park Service and 
Salinas National Monument Park headquarters for their help in 
providing information and access to the pueblo and mission 
sites. We would also like to acknowledge the University of 
New Mexico's Graduate and Professional Student Association 
and express our appreciation for their support in providing 
funds to complete this work. 
6. REFERENCES 
Cooper, E. S., 2002. "Photogrammetry at the Narrows," Rock 
Art in Arkansas, University of Arkansas, 
http://rockart.uark.edu/ narrowsphotogramm.html. (accessed 10 
Sep. 2002). 
Giffords, G., 1988, Spanish Colonial Mission Churches. 
Southwest Parks and Monuments Association. 
Turpin, S. A., Watson, R. P., Dennet, S., and Muessig, H., 
1979, Stereophotogrammetric Documentation of Exposed 
Archaeological Features, Journal of Field Archaeology. 
Wilson, J. P., 1993, “Quarai: A Turbulent History," in Salinas, 
Noble, G. D., ed., Ancient City Press, Santa Fe, New Mexico.