W artykule wykorzystano metody trójwymiarowej wizualizacji w celu stworzenia rekonstrukcji jednej z najstarszych ukraińskich drewnianych cerkwi, znajdującej się w miejscowości Potełycz. Oryginalność zabytków tej rangi cechuje go jako jeden z nielicznych w Europie Wschodniej w kategorii starej architektury sakralnej z bogatymi tradycjami. Przeanalizowane zostały również techniki rekonstrukcji 3D w zakresie otaczającego krajobrazu. Trójwymiarowa rekonstrukcja z zewnątrz i we wnętrzu cerkwi, na podstawie naziemnej fotogrametrii, stanowi najczęstszy sposób obserwacji zmian w jej strukturze. Dostępne dane historyczne zostały wykorzystane w celu rekonstrukcji 3D nie istniejącej już piramidalnej kopuły cerkwi, zniszczonej w 1736 roku. W pracy przedstawiono specyfikę zastosowania technologii 3D w odbudowie cerkwi, jej dzwonnicy i otaczającego ją krajobrazu kulturowego, z uwzględnieniem poszczególnych jego elementów. W technologii 3D został również opracowany model konkretnych roślin, które zostały wykorzystane w rekonstrukcji otoczenia cerkwi i jej dzwonnicy oraz mają poprawić stabilność gruntu. Za pomocą różnych metod modelowania cyfrowego zrobione zdjęcia zostały zestawione ze sobą w celu znalezienia najbardziej efektywnego sposobu rekonstrukcji cerkwi z zewnątrz i z wewnątrz, dzwonnicę oraz ich otoczenie. Odpowiednie wykorzystanie wszystkich tych metod zapewnia optymalne rezultaty i zachowanie cerkwi na przyszłość.
These days three-dimensional reconstruction of architectural objects becomes more actual every day (Remondino, El-Hakim, 2006, 291). Three-dimensional visualization and processing finds its application in various areas, mainly in industry (Poussart, Laurendeau, 1989), medicine (Dun et al., 1989, 1364), entertainment industry (Debevec, 1998) and recently in cultural heritage as well (Berndt, Carlos, 2000, 37). Based on terrestrial photogrammetric and historical documentation it is possible to reconstruct cultural objects, including some elements of their structure that might have been destroyed. As a result, the reconstructed 3D image becomes the only source that illustrates the cultural architectural object the way it could be found many years ago.
Since archive management of cultural heritage recently becomes to benefit from digital information (Lu, Pan, 2009), 3D reconstruction based on digital documentation seems to play a important role in it. Particularly, researches on cultural heritage can benefit from high precision of three-dimensional reconstruction of architectural monuments in order to ensure greater protection, to examine possible changes in their structures and finally to improve their conservation. Laboratories from different countries are still testing and elaborating different systems and conducting innovative projects in digitalization of the studies on cultural heritage (Levoy, 1999), which method will enable the maintenance of these cultural objects not only in their landscape but in documentation as well.
Three-dimensional reconstruction of relics provides an enormous perspective for presenting cultural heritage, including wooden churches and their bell-towers, within the landscape they are located in. Moreover, it also facilitates the widely understood renewal and protection of cultural landscape. This protection should concern not only the church as a sole object, but also the near standing bell-tower and their surrounding. It is crucial as well to ensure protection of the hill-sides on which the church is located in order to prevent future sliding of earth and protect the soil from possible erosion. Proposed for this purpose plant species shown in 3D visualization will not only aid fighting erosion and getting the soil beneath the church more stable, but will improve the esthetic value of cultural landscape as well.
The aim of this work is to illustrate image-based modelling conservation approach. There exist different ways of effective application of three-dimensional visualization not only for architectural objects, such as the church (its internal and external parts, including visualization of not longer existing structure’s elements) and bell-tower, but also for church’s surroundings – geomorphologic objects, such as hill-sides with diverse inclination and plants. Mainly, these plant species may act as a prevention of future soil deformation, which is the base for the church, for an instance by hardening it.
2. Material and methodologies
Ukrainian wooden temples as monuments of sacral architecture are considerable spiritual centers and unique architectural objects. They should be reconstructed not only in the ordinary manner, but with the use of three-dimensional technology as well. Currently the majority of those well-preserved Ukrainian wooden churches are located in Western Ukraine and belong to parishioners of Ukrainian Greek Catholic Church. In Ukraine there are around two thousands of wooden churches. Around 18.3% (469) of them are considered as relics and are under State’s protection in terms of their conservation (Slipchenko, Mohytych, 2005). For an instance, only in Lviv province there are 777 wooden churches, which are to be found in 20 districts (such as Brody district – 28 wooden churches; Busk – 36; Gorodok – 25; Drohobycz – 67; Zydacziv – 58; Zhovkva – 39; Zolocziv – 31; Kamjanka Buska – 28; Mykolajiv – 16; Mostyska – 35; Peremyshlany – 13; Pustomyty – 24; Radechiv – 42; Sambir – 43; Skole – 45; Sokal – 41; Staryj Sambir – 65; Stryj – 42; Turka – 53; Javoriv – 46).
Almost all of the mentioned above churches in Lviv province are still functioning and conducting their spiritual activities. Nevertheless, almost 90% of these churches require renovation and more effective protection, including one against fire that is a common menace for those relics. This data provokes us to deduce that the situation is not satisfactory or even acceptable, since if nothing is done to improve the situation then those elements of cultural landscape will disappear.
We have chosen to analyzed the oldest of them – the wooden church of Holy spirit in village of Potelycz, Zhovkva district, Lviv province. Currently, this is the oldest functioning Greek Catholic church in Ukraine which is covered by State’s protection as a architectural relic of national significance (Chernyavskyj, Savka, 2004, 252). It was build in 1502, replacing the church of Borys and Hlib that existed there before however was burned by the Tatars. The church of Holy Spirit was build out of private funds by local potters, whose products were well-known in Europe. The church was surrounded by workshops were the pottery was made (Kozak et al., 2010, 51). The Village of Potelycz was found in 13th century (in 1498 the town Potelycz was given Magdeburg Rights that was in force during four centuries), nonetheless the town’s prosperity was disturbed by difficult times and other circumstances (a huge trade route that led from Lublin to Lviv and went through the town of Potelycz was moved and since then it led instead of Potelycz through town of Rava-Ruska). That moment is considered to be the beginning of decline of Potelycz. Due to those events, at this time Potelycz is only one out of many Ukrainian border villages, although a hundred years ago it was a prosperous town.
The church of Holy Spirit is an example of boyko type architecture. In 1736 covering of the altar was changed – the pyramidal dome was replaced by baroque one. The doors adorned with artistically made wrought hinges are preserved till today. The inside of the church is dominated by an old iconostasis with an icon of Deesis, painted by Ivan Rutkovicz in 1683. On the walls there can be still found a preserved polychrome (traditional wall-paintings) from around 1630’s presenting the scenes from the Passion of Christ. The iconostasis and the polychrome were renovated in 1970-1972. The oldest and the most unique is however the icon of Borys and Hlib from the end of 15th century and traditional icon of “Bohorodycja” since 17th century.
Wooden churches were mostly built on a cruciform plan (Augustyn, 1997, 114), usually triple with three chambers. Its architecture has never been separated from outer environment. The structural design is actually within this landscape, reflecting some of its elements by the structure. Due to this fact all architectural forms of the church were constructed in accordance with the surrounding nature. This perception is the basis for the rule of assimilation which is manifested primarily by the building material – the wood. The natural color of the beams, wall sheathing, wood tile (local name in Western Ukraine – “gont”) – all these elements link the church with the surrounding landscape, not only because of its building material but also by the similarity to the forms of living trees and their crowns. There has always been emphasized the contrast which can be noticed in configuration of geometrically clear straights with a lot of contours and shapes of different peaks. Baroque domes of churches, surmounted with crosses, provide gentle and harmonious transition from architectural volume to surrounding space in the landscape – opened beneath the dome of the sky. This particular surmounting of the church creates the most noticeable and significant religious element (Shcherbakińskyj, 1970, 29). For this certain reason the 3D visualization was presented in conjunction with the visualization of surrounding landscape’s elements (relief, plant species).
A bell-tower on a square plan (4.4 x 4.4m), whose height is 20m on nine posts, is located next to the church. This bell-tower, built in 1736, was eventually renovated in 1970. The bell-tower was reconstructed only with the use of Image Modeler.
The stages of the church’s development were illustrated in this article on the grounds of historical and graphical documents. The process of creating 3D-models of the church, its bell-tower and their surroundings was based on current digital photography. In terms of economy, this is the most effective manner used in order to create digital morphogenesis (Koutsoudis et al., 2007, 31). Data acquisition which is the first stage of our study, results in obtaining digital information that should undergo specific process, such as acquisition, analysis, recognition and exhibition (Lu, Pan, 2009). In our case, the acquisition process is simply taking a previously planned sequence of photographs. The analysis initiates when photographs are introduced and evaluated in Image Modeler and SketchUp 9 program. Then in recognition and exhibition phase those evaluated photographs are introduced in 3D Studio Max and then exhibited in the form of 3D model.
On the basis of photographic documents it was possible to reconstruct the church from the outside (Fig. 1b) and from the inside (Fig. 1c). In the modelling process the method of terrestrial photogrammetric was used.
Photos that were used in process of modelling of exterior of the church are demonstrated on the same figure as 3D model is (Fig. 1b). This technique permits to exhibit comparative possibilities of the 3D view with the view on the photos. What concerns the photos of the interior, these were taken in accordance with the scheme shown on the figure (Fig. 1c). While setting the camera in the centre of each chamber, photographs were taken as turning around (starting from 00 up to 3600) and after each turn of 3600, the angle of camera inclination was changed on 450. Four rounds of this sequence were made. Basically, photographs were taken in manner which enables them being collated together in a Image Modeler program. In this program the calibration was conducted manually, therefore main axes (x, y, z) were set in the panorama view. Then, manual measurements were introduced into Image Modeler program in the way which retains the real scale of the church interior.
Fig. 1. Technical projection and photography scheme: a) technical projection of the church; b) scheme of photographing from the outside; c) scheme of photographing from the inside.
The process of 3D reconstruction of the church consists of several stages: data acquisition concerning current state of the church; 3D modelling of current state of the church (its interior and exterior) together with its surroundings; the evaluation of the alterations that have occurred with particular elements of the church and creating models of those already non-existing (e.g. the model of non-existing dome); creating a central 3D model out of every single element that makes up the church (temple porch, nave and the altar), bell-tower and its surroundings.
The stages of digital reconstruction require to apply basic rules of reconstruction (Becker, 2009, 653) and modelling methodology. Every single element of those existing ones was separately manually measured, then digitally processed and modeled. The digital model of the church and its bell-tower, that was conspired out of 3D models, was generated with the use of photogrammetric. 3D models were gathered in a short film that shows the church from the outside and from its interior as well. In the film the camera moves in the way that different elements of the church, bell-tower and their surrounding are visible.
3. Photo documentation and reconstruction in 3D
The digital photography (Nikon D90 with the lens Nikon 18-120mm and the focal images 18mm) served as an input data for 3D modelling process. It were used in order to enable working in a high precision, permitting for none in-site work (Shashi, Jain, 2007, 40). The photographs of the interior of the church were divided into three parts (photos of the nave, temple porch and the altar).
The non-existing element in our case is the north pyramidal dome, that was replaced by baroque one in 1736. It was reconstructed on the basis of the size and dimension of the chamber that is currently located beneath the non-existing dome. This part of the church remained unchanged through centuries and therefore was an accurate foundation for reconstructing the non-existing dome. For reconstruction purposes there was used historical data as well which indicated great similarities between non-existing dome and the still existing central dome with a pyramidal shape, which is as a twin to it. Photographs of that dome served as a basis for the reconstruction in 3D of that non-existing one (Van den Heuvel, 1998, 368).
The photogrammetric that was used in our study is the method of analyzing a structure that is presented on two or more photos. In particular the terrestrial photogrammetric was used. Restitution provides a way of representing a non-existing or modified structure, which is highly important in our case in terms of non-existing dome.
Terrestrial photogrammetric was firstly applied individually to every single element of the church. The process of taking these photographs was previously planned in order to obtain a sequence of photos that are adequate for photogrammetric modelling. Using photogrammetric techniques enabled the construction of 3D models that are based on analysis of existing 2D images. In these circumstances, shape analysis was grounded on the photographs of the church, bell-tower and their surroundings as partially devastated objects (Stojaković, Tepavčević, 2009, 6).
In Image Modelling program, on the basis of photographs there were set reference points on these photos and the program automatically calibrated the position of the camera. The automatic calibration was hinder by the fact that all the walls of the church were leant to the inside, what might have been caused on purpose by the architect or by the influence of time. For this reason all possible defects were corrected in SketchUp 9 program.
After having defined all the elements on the photographs, these photographs were imported into the 3D software (3D Studio Max), where it is possible to generate all that complex geometry. Textures were automatically extracted from terrestrial images and then were put into the 3d model with the use of mapping of UnwarpUVW. These textures (resolution 4096×4096 pixels) were different according to the object they covered (the roof, external walls, bell-tower, the interior of the church). For an instance, the roof of the church which is covered with “gont”, was reflected in the 3D model with all the details, including gradual imposition of its element (Fig. 1b, 2b). The aim of this procedure is to achieve the most accurate similarity between digital model and the existing environment.
All images were made with the same focal length. In case of barrel effect deformations, it was corrected with the use of Image Modeler. All individual 3D models were incorporated into the central model which generates a complete 3D image for the church, its bell-tower and their surroundings, including the proposed plant species to be planted out.
Throughout processing all the data from terrestrial photography, historical maps and text descriptions we introduced it to the 3D software and eventually created an entire reconstruction of the church as it was in 1736 (Fig. 2a) and as it can be found these days (Fig. 2b). 3D visualizations were put on the technical projection of the church (Fig. 1a). We would like to show the church with both central and north pyramidal towers till 1736 (Fig. 2a). This reconstruction is the first and the only that exists these days, presenting the church as it was to be found in 1736 with already non-existing dome. The actual appearance of the church with central pyramidal tower and north baroque style dome is presented on the next figure (Fig. 2b). Generally, the reconstructed 3D image of the church has its walls leant to the inside (about 50) as it occurs in reality. Due to this reason, 3D reconstruction models are accompanied by the technical projection of the church.
Fig. 2. View of the church: a) before 1736; b) current.
The interior of the church is illustrated (Fig. 3) in the form of distributed three-dimensional visualization. Separate elements of the three-dimensional view are shown in numerical order at the bottom of figures. This spherical panorama view was taken in the central part of the church.
Fig. 3. Spherical panorama view of the interior: a) left side; b) front side – the altar; c) right side; d) back entrance.
Contemporary techniques of reconstruction (including innovative 3D visualization technologies) and preservation of the landscape that surrounds the church are presented as well (Fig. 4). Bell-tower was shown also on this figure. The presentation of this area was rationed out and elaborated with the use of special tools of 3D Studio Max in order to emphasize the shape and roughness of the terrain.
Fig. 4. Surrounding of the church.
The renewal of cultural landscape that surrounds such an unique relic of national significance has gradually become even more apparent. However, in 3D reconstruction it is possible not only to show how to improve the esthetic appearance but also how to preserve the soil stability of a hilly terrain. In the 3D model there are proposed some particular plant species (Aconitum firmum Reichb; Dianthus carthusianorum L.; Cerastium pumilum Curt.; Symphytum cordatum Waldst.et Kit), around the church which will firstly comply with the requirements of the hilly and unstable terrain that surrounds that church, and secondly will provide greater protection from possible soil erosion by hardening it.
This type of landscape modelling has an interdisciplinary character – demanding knowledge and skills from a wide range of fields, such as computer modelling, 3D visualization technology, sacral architecture, geomorphology of the hillside and plant ecology.
Three-dimensional reconstruction of wooden relics in the landscape with the use of digital photography became an important approach in scientific researches. It is essential in terms of landscape architecture, particularly in studies of architectural and sacral heritage. It allowed us to document in details this valuable and the oldest sacral monument in Ukraine.
Digital photography, visualization techniques and multimedia presentations give a wide range of possibilities in analyzing and documenting different relics. Taking detailed photos from different perspectives enables to create three-dimensional image which is based on the model made in 3D Studio Max. Reconstruction with the use of computer modelling is an innovative method in documenting and visualization of public space. In the meantime, digital reconstruction of a wooden church and its bell-tower as relic objects is a way of documenting information concerning old sacral wooden heritage.
These results provide a representation that could be additionally implemented for various purposes. For example three-dimensional models can be prepared and stored for Web3D application, enabling interaction with the digitally formed environment (Styliani et al., 2009, 528).
This article presents an innovative approach towards the reconstruction of a cultural landscape as a whole and each of its individual elements separately. Reconstructing every single element (the church, non-existing dome, bell-tower) separately and adding new components such as particular plant species that carry out specific function, made the 3D model being more accurate and in accordance with the landscape ecological demands. It is crucial to mention that cultural landscape, in which the church and its bell-tower are its central components, can not be analyzed and therefore reconstructed without taking into account ecological aspects. For this reason there were chosen and introduced into the 3D model plant species which are to support and harden the soil on which our key elements of cultural landscape – the church and its bell-tower – are located.
By using 3D Studio Max software it was possible to demonstrate how those who intent to preserve the cultural heritage may benefit from 3D visualizations. Since 3D visualization enables to construct an image of existing objects in the landscape therefore we decided to reconstruct those already non-existing ones (such as reconstructed pyramidal dome of the church) on the basis of digital photography. This method not only contributed to maintenance of architectural heritage by reconstructing a destroyed element of the church, but increased the value of our research as well.
Terrestrial photogrammetric, that was the base and the source of our study, allowed to conduct the reconstruction with a high precision and therefore once more increasing the value of our research. The photogrammetric technique, when introduce into 3D Studio Max, enabled us to create models for each photographed element and then to collate individual models into one central model which provide a precise 3D image of the landscape in this particular location.
The results we obtained therefore the 3D model of the reconstructed church, are fundamental in terms of their documentation for future. Since some of those reconstructed parts do not exist any more, thus they should be documented and preserved, as the only images of particular elements of the cultural heritage, that presents them in the way they were to be found.
What concerns future research, we believe that there is a great public demand in obtaining new data about the culture we live in. The application of 3D visualizations facilitates this task in terms of renewing this heritage by reconstructing cultural objects that were destroyed, what can not be done by any other technique. Hence, we expect to work on some new cultural objects in their ecological landscape and reconstructing them as they were to be found at the beginning of their existence.
The authors are grateful to the Polish Ministry of Science and Higher Education (Project Nr N N309 014638) for supporting this work.
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Hanna Kozak, mgr – asystent naukowy Katedry Kształtowania Krajobrazu KUL, dyscyplina badawcza kulturoznawstwo
Ihor Kozak, dr hab. – Prof. KUL, Kierownik Katedry Ekologii krajobrazu KUL, dyscyplina badawcza – ekologia krajobrazu
Adam Stępień, mgr. inż.– asystent Katedry Ekologii krajobrazu KUL, dyscyplina badawcza architektura krajobrazu
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