NEED OF ARCHITECTURAL PHOTOGRAMMETRY FOR ROMANIA

Authors: Prof. Dr. Eng. Lucian TURDEANU, Faculty of Geodesy, Bucharest
Conf. Dr. Eng. Cornel Pałunescu, Faculty of Geology, Bucharest


During the antiquity, many grandiose and important monuments – mentioned in the chronicles – have been built. There were built also in the Middle Age. Some of them resisted in time and they can be admired, as they are, other as ruins, and other – unfortunately – disappeared. The descriptions of the contemporaries give us only a vague imagine of what they were (the seven miracles of the world are an eloquent example in this sense). At present, there is a remarkable universal patrimony of protected buildings. every country tries to protect and preserve this patrimony.

Some buildings need urgent and expensive interventions. Not all the countries have an economy that permits the maintenance of such a patrimony (restoring and repairs). The costs touch million or billion EUROs and the governments declare themselves helpless. They try to restore and repair the monuments considered as being the most important but, due to the lack of funding, the works last a very long period.

The architectural photogrammetry rose as a need of preserving the monuments’ image in time, with the possibility of their later reconstitution. This is a preserving method for the buildings at risk of loss. The very detailed reconstitution of the façades, of the entire building, makes possible the 3D representation. The method goes perfectly together with the performances of the computers and of the processing softwares. Thus, the presentation of the aggregate can be realized as digital pattern, as well as hard copy or tri-dimensional model. Of course, it is not about the effective preservation of all the buildings at risk of loss, but photographing them through the architectural photogrammetry method is not very expensive and permits to keep the image for long time. If the preservation and the reconstitution of a certain objective is considered opportune, the images can be picked out from the archive and processed in order to obtain the tri-dimensional model. The keeping of the images is safe and do not imply special problems.

The methodology of carrying out the tri-dimensional model is the classical one, utilized in the traditional photogrammetry and does not need special devices, but highly efficient last generation computers. The software for processing data can be quite easily procured, and at reasonable costs, especially if there are applications for achieving the plans of certain objectives. The softwares can be improved by the users, as they are heavily used. The Polytechnic University of Bari is has tradition in this field and there is where the staff can be trained.

In the May 2003 edition of the review “The Magazine of Leica Geosystems” there is an article called “Statue of Liberty 3C Cyra scan provides historical documentation”. They are talking about scanning an object with an instrument made by Leica Company, named Cyrax 2500 3D Laser-Scanning. The instrument is placed in several stations, around the object, from where it can scan every detail. The idea was carried out by The College of Architecture of Texas Tech University in cooperation with Historic American Buildings Survey and The National Park Service. The precision of measuring the exterior of the statue was of _ inches. Thirteen stations have been utilized for scanning and, also, a total Leica Geosystems TCR702 station to independently assess the precision’s quality. Each of the 13 stations was maintained on position for about two hours. The scanning can be made during the day, as well as during the night. About 200 million points positioned x, y and z have been processed in a tri-dimensional model 3D and 2D for the design.

To realize the 3D model, all the points taken from the 13 stations were registered into a single point cloud consisting of polygons, often referred to as a polymesh or polygonal model. The solution given by the scanning was completed with mathematical points there where clouds interfered.

Some problems rose while scanning the head and the crown, there where the images could not catch all the details. To solve the problem, the method was combined with the photogrammetry.

The 3D model has been made and high-resolution photos were utilized to create a mini GIS system in order to ensure the maintenance and the management of the statue.

As we can see in the article, the technology of obtaining a 3D system of the monuments shows a real progress. The scanning of objectives proves to be a very good solution in this sense, but it is vital to be completed with special photos or with classical control measurements. Certain details cannot be visualized with Cyrax 2500 3D Laser-Scanning. These details can however be taken by photographing.