Some Metric Documentation of Cultural Heritage in Poland by Spherical Photogrammetry

Abstract

Poland is a country with very rich CH, mainly in architecture. Churches, monasteries, castles, important buildings of noticeable workmanship are spread all over the country. I have made some experiences of metric documentation using a technique called Spherical Photogrammetry. Some projects are fully exploited; some are only at the orientation stage. Nevertheless, the philosophy is to document and build-up an archive: in case of need one can retrieve this documentation and use it to provide information, measurements, and so on. Spherical Photogrammetry is a new photogrammetric technique making use of the so-called spherical panoramas. They are obtained taking pictures from the same station point, partly overlapping, and covering up to 360°. Once downloaded in the computer they are projected on a virtual sphere having with the same center, then stitched together and projected in the cartographic plane with the so-called azimuth-zenith or longitude-latitude projection. The two orientation angles, horizontal direction and zenithal angle, can be measured, like in a theodolite. A software package has been prepared called Sphera. The 3D object extraction is assured, provided two or more oriented spherical panoramas, taken from different station points, by intersecting projective straight lines. The panorama orientation takes place in steps: (1) model formation by coplanarity, (2) absolute orientation, (3) block triangulation with independent models, (4) least constraints block bundle adjustments. The properties of the panoramas are many: FOV up to 360°, covering the entire visible space, the resolution is very large, much bigger than the one of any available commercial camera. Therefore the surveying time on place is short, enabling to produce large documentation projects in an easy and fast manner. Up-to-now no commercial software package is available, but I believe and hope that it will be available eventually. The main difficulty is in that any orientation and plotting is manual, making the procedure slow and difficult in the restitution phase. The examples shown are Saint Florian and Rynek market square, Kociny Palace in Kracow. Krakow has a large tradition in arquitectural photogrammetry. Untill the years ‘80 the Laboratory of Photogrammetry for Architecture in Krakow was the largest and most important in the world (Krakowskie przedsiebiorstwo geodezyjne).