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mation obtained better - more complete and more accurate - but also that it is cheaper. A smaller investment is required given the 
low cost of the systems necessary to obtain the final result. 
The cost of the equipment is determined by the fact that it pays for itself given the amount of uses it can be put to. Low cost informa 
tion selection systems provide an immediate return, and on their first use may - depending on the work - return the whole cost of the 
investment. In the case of more sophisticated equipment - three-dimensional scanners - the price and the quality are so dynamic that 
we might find ourselves in the same situation as with low cost equipment. 
3.5 Efficiency 
The combined evaluation of the processes used, of the time invested, of the costs and of the results, will provide the keys to the final 
evaluation of our system. Constant self-evaluation will provide feedback to the process, adjust the most unfavourable aspects and 
turn the process of documentation of architectural and cultural heritage into a dynamic science. 
4. THE PROCESS 
The process used is apparently simple. After correct documentation - photographing and measuring initial digital processing is 
performed to filter information. A Photographic Information System is then developed so as to be able to handle the object from 
different scales and positions. The following step involves performing photographic rectification, which will give us the photo-plans 
of the object. This is followed by the metrical digital image, which is put through different filtering or processes, in this case with the 
existing programs on the market, to obtain different digital outputs of the rectified photo, depending on our needs and wishes. The 
next step is to vectorise the image-plan obtained before finally incorporating the result into the photogrammetric model of the whole 
courtyard. 
5. THE RESULT 
Finally, it should be pointed out that there are other earlier examples carried out by us as well as many more performed by others. 
However, one of the most relevant features in our case is that the result may be incorporated directly into the drawing files obtained 
from different surveying methods, obtaining - with the previously established accuracy - a complete three-dimensional object as the 
result of the efficient combination of processes. 
* The following people have also co-operated in this work: Roberto Espino, Sagrario Moraleda, Ascensión Hernández, José Ignacio 
Sánchez and Raquel Suárez.