THREE-DIMENSIONAL ANALYTICAL MODEL OBTAINED BY PHOTOGRAMMETRY 
SEGMENTATION, OPERATION AND APPLICATIONS IN THE FIELD OF ARCHITECTURAL RESTORATION 
The case of St. Mary’s Cathedral in Vitoria-Gasteiz, Álava, Spain 
Leandro Cámara y Pablo Latorre, architects, Madrid 
C/ Puerto de los Leones 1, oficina 111, Majadahonda, 28.220, Madrid, Spain. Phone: +0034-916.375.388, Email: lyc@arquired.es 
KEY WORDS: Historical Architecture, Mapping Systems, Documentation, Analytical Photogrammetry, CAD, 3D Model 
ABSTRACT 
Historical buildings present a deformed and eroded shape and geometry, increasing the three-dimensional complexity of their 
structure. The recording of analytical photogrammetry on CAD programs allows complete 3D analytical models to be drawn of the 
buildings. These programs present all visible surfaces in a single drawing and use a single coordinate system that allows each line to 
be placed in its real position in space. These line models are transparent and thus do not hide lines in the background. They do 
occupy a large amount of memory, which makes computer manipulation more difficult. To solve this problem, the 3D model must be 
broken down into drawing files and layers. Each drawing file includes the plotted lines of a building element, identified by the 
typology of the element and its position within the space of the building. The lines are separated into layers based on their direction 
and typology (edges, contours, cracks, etc.) The set of files comprising the 3D model are managed directly by designation or 
graphically by using a simplified guide plan where each line is linked to a file. The analytical 3D model is a computer model of the 
monument that allows different views to be displayed and several types of analyses to be performed - metric, geometric, construction 
and structural - which would be impossible without this tool. A Monument Information System (MIS) can be created through the use 
of a computer which connects each one of the items drawn with an external database system containing information on studies of the 
monument. 
“... Sculpture acts in three dimensions, but man remains 
external, separated, viewing from outside. Architecture, 
on the contrary, is like a large, hollowed-out sculpture, 
where man can enter and roam. ” 
“..., the reality of the object goes beyond the three 
dimensions of the perspective; to fully represent it one 
would need an endless number of perspectives from the 
endless number of viewpoints. There is thus another 
element, in addition to the three traditional dimensions, 
and it is precisely the continuos movement of the line of 
sight. Thus was time baptized the “fourth dimension ”... ” 
“...the most widely used methods of mapping buildings in 
the history of art and architecture use: a) floor plans; b) 
elevations and section drawings; c) photographs. We 
believe that these means, taken as one or as a group, are 
not enough to fully represent the architectural space. 
Nevertheless, it is useful to study this problem more 
closely because - while we do not yet have better systems 
of mapping - our job is to study the techniques we have 
and make them more effective”. “Saper vedere 
I’architettura”, (Bruno Zevi, 1949, 1991). 
View of St. Mary’s Cathedral from East 
L THE THREE-DIMENSIONAL NATURE OF ARCHITECTURE AND ITS GRAPHIC REPRESENTATION 
Of all objects fabricated by man, architecture offers the most significant spatial and three-dimensional features since by its very 
nature, it is to be used by entering into a hollow interior. This “wrapping” aspect of architecture allows man to isolate himself from 
the open, exterior space and enter - as if into a cave - a closed space, designed and built by him, with the dimensions, shape, colors 
and textures most suitable for the exercise of a specific activity. A building is a large, constructed volume, with its exterior shape 
determined by the spaces found inside of it - thus its three-dimensional nature. These features and their dimensions make it difficult 
for us to understand a building by observing it from a single viewpoint. To be able to fully visualize its structure, we must travel 
through it, circling the exterior perimeter and accessing the interior of each one of its spaces. 
This spatial complexity of a building also obliges us to break down the configuration into design and presentation processes and use 
plans and models to represent each one of the elements, making them easier to understand. To include all of the spatial complexity of 
a structure, we project it on a series of horizontal and vertical planes that divide its volume and use these in conjunction with the most 
significant plans of the structure. This system, usual for the mapping of buildings using floor plans, elevations and sections, denies a 
three-dimensional view and results in elements that are not parallel to these sectional plans or are also sloping, with a variable 
Proceedings 18 th International Symposium CIPA 2001 
Potsdam (Germany), September 18 - 21, 2001