Virtual reconstruction of the Trinity Cathedral in Stavropol-on-Volga in the first half of the twentieth century: sources, methods and research technologies

Lysenko Kristina Dmitrievna Master's Degree, Department of Historical Informatics, Moscow State University 119991, Russia, Moskovskaya oblast', g. Moscow, ul. Lomonosovskii Prospekt, 27 k.4 kr1stin7@yandex.ru Other publications by this author

Introduction

The history of the city of Stavropol-on-Volga, as well as the Trinity Cathedral, was discussed in more detail in the article "Virtual reconstruction of the Trinity Cathedral in Stavropol-on-Volga (XVIII-XIX centuries): sources, research technologies, visualization of results" ^[1]. In this case, we would like to focus on the study of the later (last) version of the cathedral of the twentieth century, the features of working with sources used in the virtual reconstruction of the temple, as well as a step-by-step description of the creation of 3D reconstruction and the experience of its application in the museum exposition.

Note only that Stavropol-on-Volga is a city with a unique destiny, almost completely disappeared at the bottom of the Kuibyshev (Zhiguli) reservoir and revived in a new place under a new name – Togliatti. We will make some terminological remark in advance: here and further in this work the names of the city of Stavropol and Stavropol-on-Volga will be used. Both of these names are acceptable when referring to the modern city of Togliatti in its early period of existence. Stavropol-on-Volga or Stavropol Volga city was sometimes called to differentiate from the city of Stavropol, founded in the Pre-Caucasus in 1777. In 1964, the city was renamed Tolyatti.

In the post-war 50s in the life of Stavropol, special attention was paid to the construction of the Kuibyshev hydroelectric power station. Stavropol-on-Volga, which stood apart from the railways, received access to the country's railways with its appearance and began to grow rapidly. At the end of October 1955, the Volga was blocked, and in December the first hydroelectric power plant unit gave current. The station became part of the Unified Energy System of the country. Energy from Zhiguli was supplied to cities and villages of Central Russia, the Urals, Kuibyshev, Ulyanovsk, Saratov and other regions. A reservoir with an area of more than 6.5 thousand square kilometers, 500 kilometers long, and up to 40 kilometers wide was formed. The reservoir covers the borders of three autonomous republics and two regions. You can see how large-scale the flooding was on the photos of Stavropol before and after the flooding (see Figure 1-2).

Fig.1-2. View of Stavropol from the same place before and after flooding. Copies from the collections of the Togliatti Museum of Local Lore, 12.05.2022

Nowadays Zhigulevskaya HPP is one of the main bases of the unified energy system of the European part of Russia. The quiet, provincial, resort town remained in the past, having dissolved at the bottom of the Kuibyshev reservoir ^{[2, pp.237-238]}. At this stage, a new round of the history of the now industrial city of Togliatti has begun.

Let us also recall the role of the Trinity Cathedral in the history of Stavropol since the time of the fortress. The Trinity Cathedral, built in 1738 in Stavropol-on-Volga, was one of the very first buildings of the city and was the city-forming one. Temples in provincial Stavropol, as in any Russian settlement, were what formed the basis of a person's life - here they were baptized, crowned, buried, made solemn exits on holidays.

First of all, during the construction of the city, it was the church that was built, since it was ordered to unite the baptized Kalmyks among themselves mainly on the basis of religion. The Kalmyks were mostly nomadic people and were not used to living in one place for a long time; for them, moving to the city was quite stressful and difficult condition ^[3]. Nevertheless, the church at that time played a huge role in rallying the people, which is why its construction, as well as further restoration and completion, has always been given priority attention by the commandants of the fortress city and the administration.

In the previously mentioned article ^[1], a more detailed history of the cathedral is considered. Here we will give the chronology of its rearrangements and transfers:

1738 – the first version of the cathedral was built. The street leading to it is named Cathedral.

1743 – a new five-domed wooden cathedral was built, since the old one seemed small to V.N. Tatishchev.

1750 – construction of a new, stone cathedral, as the old one quickly fell into disrepair.

1809 – disassembly and transfer of the cathedral to a new location in connection with the destruction of the coast and the acquisition of Stavropol new territories to the east.

1813 – the construction of the cathedral in a new place, 1815 – its consecration. The new cathedral had a height of 31 meters and could accommodate up to 800 people.

1842 – the addition of a 55-meter bell tower to the cathedral.

1936 – the cathedral was closed by the decree of the Presidium of the Kuibyshev Regional Executive Committee. The building houses a granary.

1944 – in connection with the Great Patriotic War, the cathedral was opened to maintain the spirit of the faithful.

1955 – the cathedral was closed and blown up, and subsequently flooded with water during the construction of the Kuibyshev hydroelectric power station.

The Trinity Cathedral stood until 1955. Due to the formation of the Kuibyshev reservoir, the city of Stavropol fell into a flood zone and therefore had to be moved to a new location. Everything that could be transported to the new territory was transported, and the Trinity Cathedral was decided to be dismantled (otherwise it could interfere with shipping when flooded). In addition, the local authorities believed that it would be indecent for future builders of a communist society to transport the temple to a new socialist city. They hoped in this way to rid the townspeople of faith. But it was not possible to disassemble the temple: the church was built very firmly. The masonry of the Trinity Cathedral was so strong that the brick crumbled, and the seams did not break. The building was dismantled for several months, then they still used explosives. After the summer church, i.e. the Trinity Cathedral itself, was dismantled with such difficulty, the winter one, arranged in the bell tower, was blown up. Only under a powerful explosive charge the church collapsed (see Figure 3), and a red-brown cloud hung in the air for more than two hours. "At that time I was sitting on the mountain, in a Portposelka, I saw the explosion of the church. A column of fire and smoke shot up into the sky, stayed there for a while, and then smoothly sank to the ground. We, boys and girls, ran to see what was left of the church..." - this is how Nina Petrovna Savkina, a native of Stavropol, recalls this episode of her life ^[4].

For a long time, after the flooding of the former territories of Stavropol-on-Volga and the temple, there were legends that the cathedral was not actually destroyed and in clear windless weather you can see a cross over the water. However, many divers who descended to the bottom of the Kuibyshev (Zhiguli) reservoir refuted this information: part of the foundation overgrown with silt is all that remains of the Trinity Cathedral ^[5].

The purpose of this work is to create a 3D model of the Trinity Cathedral before its destruction and flooding, as well as to describe the experience of using 3D modeling in museum practice on this example.

Fig.3. Trinity Church after the explosion in 1955. A copy from the collections of the Togliatti Museum of Local Lore, colorized in the neural networkDeepAI

Overview of sources

To perform work related to 3D modeling, a wide range of sources of various types should be involved. One of the features of the source base of virtual reconstructions is its complex nature. Pictorial sources, photo and film documents come to the fore, at the same time, as in any historical research, written documents are used (narrative sources: literary works, memoirs, correspondence, etc.), including varieties of clerical documents – reports on research works (R&D) and scientific researchtechnical documentation (NTD) ^[6].

In this study, in addition to written sources, visual sources (in particular photographs, drawings, newsreels) and Internet resources are also used. Let's consider the sources based on their species classification.

Written sources.

Let's start with a review of archival sources. There are not many of them, but they are very important for recreating the historical context of the time we are studying. This work includes records from two archives: RGADA (Russian Archive of Ancient Acts) and TSGASO (Central State Archive of the Samara region). We use information from the 248 RGADA foundation – "The Senate and its Institutions" ^[7], in particular, these are the journals and protocols of the Senate. Sheets 113-171 from book 150 contain information about the construction of the city of Stavropol, the allocation of territory for settlement to the Kalmyks, as well as the Senate's decision to lay a stronger Trinity Cathedral in 1747.

We also turn to the fund 3219 of the TSGASO archive ^[8] — these are the materials of the Council for Religious Affairs under the Council of Ministers of the USSR for the Kuibyshev region. There are statistical reports on the affairs of churches, including decrees on their opening and closing, in particular, there are decrees concerning the Trinity Cathedral. Fund 32 ^[9] is the affairs of the Samara ecclesiastical consistory, for example, papers on appointment to church positions; reports and characteristics of candidates; tonsuring in the monasteries of the diocese; supervision of the maintenance of church books (metric, etc.); management of the bishop's house, its property, as well as the management of monasteries and temples. Historians V.N.Yakunin and P.S.Kabytov rely on both of these funds in their research when studying the history of the Samara Region and Stavropol-on-Volga.

Descriptive materials of contemporaries, researchers and travelers are important in the implementation of virtual reconstruction.

For example, well-known encyclopedists P.S.Pallas and I.I.Lepekhin left evidence about the life and everyday life of Stavropol Kalmyks. They led the detachments of the 1st scientific expedition of the Russian Academy of Sciences, the purpose of which was to study and describe the natural resources of the edges of the Russian Empire, the way of life and customs of their inhabitants. On October 1-5, 17, 1768, researchers visited Stavropol ^{[10, p.13]}. P.S.Pallas compiled mainly natural descriptions of the regions he visited, described the features of flora and fauna. Therefore, the work of Ivan Ivanovich Lepekhin is of greater interest to us ^[11]. In his work, he describes in some detail the size of the fortress of Stavropol, its structure, the location of the city relative to the coast, tells who lived in Stavropol and in which zones. This information is very important when recreating the environment of the temple.

The work also used sources of personal origin, namely materials of memories. Valuable information is provided by a fragment from the memoirs of Alexander Nikolaevich Naumov (1867-1950), published in the collection of documents "Stavropol-on-Volga and its surroundings in memoirs and documents" ^[12]. A.N.Naumov was a nobleman, the owner of large land plots in the Stavropol district, and in his memoirs he describes Stavropol as he remembered it also adds some historical facts and descriptions from an earlier time when the fortress city was founded. He also tells how majestic the Trinity Cathedral seemed to him and gives a description of it. These data are very important when recreating the appearance of the temple environment, as well as the temple itself.

The following source contains relevant information for this study. We are talking about an appendix to the collection of resolutions and orders for the Samara diocese on monasteries and churches ^[13]. The collection was published in 1899, the appendix to it gives a chronology of the rebuilding of the cathedral, as well as describes the changes that have occurred with its iconostasis.

We consider the work of Archpriest Dmitry Nikolaevich Orlov (1824-1887), a pupil of the Kiev Theological Academy, to be particularly valuable and the main source of this research ^[14]. The book gives a detailed description of the history of Stavropol since its foundation and the construction of temples on its territory. Here you can learn not only about the rebuilding and appearance of the Trinity Cathedral itself, but also about the changes in the fortress city itself, the location and appearance of buildings, as well as changes in the layout of the city after its relocation in the early XIX century. The value of the source also lies in the fact that it contains a detailed description of the dimensions of the temple and the bell tower with an accuracy of a yard, as well as the purpose of their premises and their location inside. Given that there is no drawing or plan of the cathedral, this source is perhaps the most important for us. In addition, it is the closest source to the time of the construction of the temple. The book was published in 1882, and its author is a contemporary of Stavropol–on-Volga after its first transfer and the construction of the latest version of the temple.

An important source for studying the Trinity Cathedral is the monument card stored in the Togliatti Museum of Local Lore. The document contains a detailed description of the material and architecture of the cathedral with emphasis on the characteristic features of its ornament.

In the next block we will consider the pictorial sources.

The main visual sources were provided by the TCM (Togliatti Museum of Local Lore) from its own funds.

The plan of Stavropol-on-Volga for 1951 gives a detailed idea of the location of the Trinity Cathedral relative to other city buildings, the river and the mountains. It is easy to compare it with photos, which later helped us to place the cathedral in a virtual environment at its original location.

A lot of photos from the pre-revolutionary period and the middle of the XX century allowed us to examine the temple and the bell tower in all details, and also, with proper use of the Match Photo software function, they helped to correlate the dimensions of the temple with those described in D. Orlov's book, and simplified the creation of a reasonable 3D model.

In addition, we have at our disposal a watercolor, a drawing and a postcard with the Trinity Cathedral. They also helped to restore exterior details, either lost or highlighted in photographs of the XX century.

Further, the cartographic material should also be taken into account.

Cartographic sources. To build the relief of the surrounding area of the temple, an overlay of maps was used. This is an American map of Syzran (the legend says "SYZRAN`", but the map goes far beyond this city and contains several more adjacent regions of the Volga region, including the city of Stavropol–on-Volga - approx. author), compiled by the US Army Cartographic Service in 1954 ^[15] and a map of the area flooded by the Kuibyshev reservoir in the Ulyanovsk region in 1955, presented on the Internet resource Retromap ^[16].

Next, we turn toInternet resources.

For our research, a web portal called the Togliatti Wikipedia is of interest ^[17]. In relation to this study, materials from two sections of the site were used: "Origins" ^[18] and "History, social studies, local history" ^[19]. On these pages of the site you can find information about the history of the cathedral, its architectural features during the rebuilding, as well as details of the first (1809) and second (1953-1955) transfer of the city of Stavropol.

In addition, the PastVu resource was used - a project to collect evidence of the past. Here it was possible to significantly replenish our collection of photographs of Stavropol-on-the-Volga, as well as the Trinity Cathedral.

The following resources were used in the study: DeepAI ^[20], Colourise ^[21]. They are neural networks into which we uploaded black-and-white photos of the Trinity Cathedral, and systems based on various shades of gray restored the colors in the pictures. Thus, we received color photographs confirming our hypothesis about the main color of the temple, as well as about the colors of its materials.

Analogues of churches as sources. When creating a virtual reconstruction, it is important to analyze the analogues of the buildings under consideration – they can help complete the full picture, suggest relevant material, reveal details and details of architectural elements.

Since there is no drawing of the temple under study, first of all, a search was made for cathedrals similar in architectural style and time in various regions of Russia for a hypothetical reconstruction of a possible drawing of the Trinity Cathedral. The most suitable temple was found in Bogoroditsky district of Tula province. This is the Kazan Church in the Bogoroditsk estate (see Figure 4) ^[22]. The author of the drawing, dated 1773, is I.E. Starov.

Fig. 4. The project of the Kazan Church in the Bogoroditsk estate. Plan, section and two facades. Plan. Starov I. E. (1745-1808). 1773 Tula province, Bogoroditsky uyezd, Bogoroditsk

The design of the Trinity Cathedral and this drawing have common features: the presence of three porticos with columns on three sides of the temple, as well as a rounded eastern part of the temple. During the construction of the model, a reconciliation was carried out with this plan to find out the possible sizes of columns, openings and the overall composition of the temple.

As another analogue, we took the Church of the Holy Life-Giving Trinity in Novokhopersk, built in 1910: since April 2017, work has been underway to restore it in accordance with the project of A.A.Radin (JSC "RAS") and there is a virtual model of this temple on the project website ^[23] (see Figure 5). There is a similarity of the external plasticity of the cathedral of Novokhopersk with the Trinity Cathedral in Stavropol-on-Volga: the decoration of the roof of the bell tower, the dome and spire on its roof, the design of the openings of the belfry, the decor of the porticos at the entrance to the temple, as well as windows. This model was also used as a reference when modeling the decorative elements of the temple.

Fig. 5. Virtual reconstruction of the Church of the Holy Life-Giving Trinity in Novokhopersk. Photo from the website dedicated to the Trinity Cathedral of Novokhopersk

Analogs are also useful at the texturing stage. For example, the church in the name of Archangel Michael (1829) in the village of Russian Settlement, in addition to the general similar architectural features, gives an idea of the materials of the temple. Judging by the photo (see Figure 6) ^{[24, p.106]}, this temple was also built of red brick, and later covered with white plaster, like the Trinity Cathedral. In addition, the temple gives an idea of the texture of the roof (lead), which is also useful at the texturing stage.

Fig.6. The Church in the name of Archangel Michael (1829), village of Russian Settlement, Krasnoyarsk district of Samara region. Photo from the monograph by Vedernikova T.I. et al. ^[24]

Note also the church in the name of the Life-Giving Trinity (1813) in c. Yekaterinovka of the Bezenchuk district of the Samara region on the left bank of the Volga (see Figure 7).Analyzing the similarities of this temple with ours, in addition to the same name, you can notice some other similarities of the general concept, namely: the roof of the drum, its material. Thus, texturing the drum roof, we paid attention to its device in this analogue.

Fig.7. The Church in the name of the Life-Giving Trinity (1813) in S. Yekaterinovka of the Bezenchuk district of the Samara region. Photo from the monograph by Vedernikova T.I. et al. ^[24].

One of the closest buildings in time and place was the Assumption Church, also built in the city of Stavropol a little later than the Trinity Cathedral. Its building was partially preserved, having turned into the Stavropol Regional House of Culture in the XX century (see Figure 8). It served as a reference point for us when modeling the doors of the cathedral, as well as the ornament of the semicircular windows above the doors.

Fig.8. Stavropol regional House of Culture (RDK) in the building of the former Assumption Church on the street Cooperative (Posadskaya). Copy from the collections of the Togliatti Museum of Local Lore, 12.04.2022

Thus, the source base of this study is wide and covers various types of sources: archival materials, memoirs and descriptions of contemporaries, visual and cartographic material, Internet resources. The historiographical material is also sufficiently developed: quite a lot of research has been devoted to the history of Stavropol, but there have been no attempts to recreate the disappeared city in whole or in part in the form of virtual reconstruction, which makes our research particularly relevant. By using examples of analogs of churches, it is quite possible to fill in some gaps, in particular, in the texturing section, and make the virtual reconstruction as close to reality as possible. Thus, sources, literature and analogues allow you to make all the necessary calculations and constructions, as well as perform all tasks and achieve the goals of this study.

Features of three-dimensional reconstruction technologies for the preservation and study of objects of historical and cultural heritage

Creating a virtual reconstruction of the Trinity Cathedral is the main part of this work. It is the use of three-dimensional modeling technologies that gives us the opportunity to analyze, synthesize and represent the source base in this kind of research, and also allows us to contribute to the preservation of historical and cultural heritage ^[25]. This problem of preserving historical and cultural heritage is always quite acute in historical science. Many monuments are damaged as a result of various causes: time, the human factor, natural disasters, and many disappear for good. Since ancient times, historians have tried to leave the disappearing monuments in the memory of subsequent generations by making sketches, drawings and engravings of them. All this, of course, was done by hand and on paper, without claiming authenticity and accuracy of the object of restoration. However, modern technologies allow us to get much closer to recreating historical and cultural heritage monuments in their original form.

The 3D modeling method has been used relatively recently in historical research, but it quickly began to gain popularity and develop in application to completely different goals and objectives set by the researcher. Historical 3D reconstruction is developing rapidly due to the improvement of three-dimensional modeling technologies. They allow researchers to create historically accurate, realistic virtual reconstructions of monuments of the past, allowing them to solve the problem of preserving cultural heritage. However, it is precisely in the rapid pace of development that the problems of this direction lie, since researchers need to improve their skills in applying this method at exactly the same speed in order to keep up with the times.

It is worth noting that, unlike the use of 3D modeling technologies in the creation of completely new, unique objects, in the process of historical reconstruction of lost monuments of historical and cultural heritage, these technologies inextricably follow together with the traditional method of processing written and visual sources. Having a set of sources characterizing the reconstructed object, in combination with 3D modeling methods, the historian has the opportunity to restore the object as close as possible or even identical to the original ^[26].

As noted earlier, when working with the use of 3D modeling methods, a historian needs to have the skills and tools of several professions at once. He must understand not only history, but also architecture and information technology. And in larger-scale projects of virtual reconstructions, the historian sometimes needs to resort to the help of professional architects, local historians, archaeologists and programmers.

In our study, 3D modeling methods will help solve the specific historical tasks associated with the virtual reconstruction of a completely lost monument of historical and cultural heritage, which played an important role in the formation and development of the city of Stavropol-on-Volga.

Choosing a software package for virtual reconstruction

The basic construction and creation of a virtual reconstruction took place in the Sketch Up program. This program allows you to maintain absolute accuracy in constructions, ensures compliance with drawings and dimensions. In addition, the program has enough tools to select the units of measurement of the future object, as well as to create shapes, ornaments and elements of any complexity.

Also, the functionality of the program allows you to use the technology of correlating objects with photos Match Photo, with which you can place a photo in a three-dimensional space and, having correctly built the projection, scale the object in the photo. In addition, it is possible to apply rough texturing in Sketch Up to prepare the model for visualization in the appropriate program.

For visualization and finishing texturing, the software (interactive virtual environment) Twinmotion, produced by Epic Games, was used. Also, this program was used for the final visualization of the project: the temple with the adjacent territory and buildings inside the fence. The decision to choose this particular program was dictated by the fact that it provides modern graphics due to a complex lighting system, which in some respects surpasses the graphics of its main competitor – Unity.

The Adobe Photoshop program was also used to process illuminated photos, as well as to overlay maps of Stavropol-Tolyatti in several time slices to restore the terrain.

In addition, the My Heritage photo enhancement service was used to process and improve the photos of the temple ^[27].

For texturing, the auxiliary online software Normal Map ^[28] was used, which allows you to deform the texture and give it a more realistic look on the final visualization of the project.

To create panoramas with the ability to view the final project from different 360° viewing points, Adobe Premier Pro was used, as well as the Spatial Media Metadata Injector program was used to encode video in 360° format.

At the end of this chapter, we can conclude that a sufficient methodological and technical complex has been assembled to support this study. These programs will allow you to create a virtual reconstruction of the Trinity Cathedral in Stavropol-on-Volga, ensure its high-quality visualization and place it in the museum exposition.

Description of the process of creating a 3 D model of the cathedral

Any virtual reconstruction begins with the formation of a database of sources, their systematization and comparison with each other. As noted earlier, the main sources for this work are photographs of the twentieth century, both pre-revolutionary and dated to the middle of the twentieth century, as well as information about the size of the temple, set out in the work of D. Orlov. The initial task was to correlate these sources with each other.

Photos from different angles were uploaded to the Sketch Up program and scaled according to D. Orlov's data. The source says: "The cathedral has the shape of a cross. Its height from the base with a dome and an apple to the cross is 13 and ? fathoms, the height with a cross is 14 fathoms and 1.5 arshins. The length of the temple from the entrance door in the narthex to the iconostasis is 10.5 fathoms, the width is about 7.5 fathoms. Having the size of the temple in fathoms and yards, it is easy to translate it into meters, taking a fathom for 213.36 cm, and a yard for 70 cm" ^{[14, p.107]}. Thus, the height of the temple was 29 meters without a cross and 31 meters with a cross, the width of the temple is 16 meters, and the length to the iconostasis is 22.4 meters. As a symbol of the temple, a cube of appropriate sizes was created, photographs were superimposed on it and, using Match Photo technology, they were scaled according to the size of the temple and placed in the program field so that on their basis it was possible to find out the size of each detail of the temple (see Figure 9).

Fig. 9. Using the Match Photo function in the Sketch Up program. On Wednesday , a copy photo was imported from the collections of the Togliatti Museum of Local Lore

In the program field, a plan of the Kazan Church from Bogoroditskoye village was placed, given earlier (see Figure 8), it was also adjusted to the scale of the Trinity Church. Periodically checking with the plan, it was possible to recreate typical elements of the temple: porticos, openings between windows and columns.

Inside the temple, also thanks to the records of D. Orlov, the walls and doors of the premises were designated: the sacristy, the pantry, the archive, the landing, and also the basement under the western porch and the apse, which housed the altar in the eastern part of the building. The author gave their dimensions and location in his work: "The sacristy is placed on the right side of the altar, and the archive is on the left. The length of both rooms, separated from the altar by a stone wall of 1 sazh and ? arsh. (265.86 cm – approx. author), and the width is 1.5 sazh. (320 cm – approx. author). <...> The iconostasis in the temple is one-tiered, 7.5 sazh long. (16 m – approx. author), it contains images of some of the Lord's and Theotokos' feasts within an oval shape above local icons. <...> In the vestibule on its right side there is a storeroom measuring 1 sazh and 0.5 arshina in length (248.36 cm – approx. author), 2 yards wide (140 cm – approx. author), on its left side there is a staircase to the upper and lower choirs. <...> Over the outer doors of the north, south and west there are canopies, each supported by four stone columns. <...> Under the west porch there is a small basement with a window and a wooden door" ^{[14, pp.107-108]}.

Thus, systematically comparing the data of written and visual sources, we outlined the foundation and a unique plan for the future 3D model of the temple (see Figure 10).

Fig. 10. The foundation of the future model of the temple in the Sketch Up program

Using the Push&Pull tool, the plan was gradually raised up to the height of the roof. In parallel, openings for windows were cut out in the walls and blind decorative niches were pressed in.

At this stage of building a 3D model, a problem arose: it was not completely clear from the photographs which openings in the temple were window openings, and which were decorative, deaf. Most of the photographs of the twentieth century were taken from one angle and it is not known for certain whether the window in the area of the western entrance to the temple was deaf or active. However, we were lucky enough to find a popular scientific article about the fate of the city of Stavropol-on-Volga, where photos of S. Melnik and O. Kapitonov from the personal archive were posted ^[29], among which there was a rare photo of the cathedral from the angle we needed (see Figure 11). Here it is quite clearly visible that the window was still on the eastern wall of the western entrance to the temple.

Fig. 11. Photo of the Trinity Cathedral of the mid-twentieth century from the personal archive of S. Melnik and O. Kapitonov with a mark of the window that raises questions

A similar question was in the symmetrical window on the west wall. It was solved based on a pre-revolutionary postcard with the Trinity Church (see Figure 12). It was a photo of the cathedral from the north side. In addition, both of these windows clearly differed in shape from the others: it can be clearly observed that there is no semicircular arch above the window on the eastern and western walls of the western entrance to the temple. More precisely, there is an arch in the niche in which the window is located, but in this part there is no semicircular opening, as on the other windows. We also took this point into account when building a 3D model of the temple (see Figure 13-14).

Rice. 12. A postcard of the first quarter of the XX century with the image of the Trinity Cathedral and the mark of the window that raises questions. Copy from the collections of the Togliatti Museum of Local Lore, 12.05.2022

Fig. 13-14. Windows on the eastern and western walls of the western entrance to the temple, differing in plastic from the rest. SketchUp

In the process of window openings design, a discrepancy was revealed in some sources. In the watercolor (see Figure 15), we observe a clearly blank niche on the apse where the altar was located.

Fig. 15. Watercolor of the Trinity Cathedral with the mark of the opening that raises questions. A copy from the Tolyattiets website (URL: http://tolyattinec.narod.ru/fotostavr.htm )

However, in all the photographs of the XX century (see Figure 5) this is not so: they clearly show that there was a window in this place. It was decided to trust the photographs more: perhaps the artist drew from memory or without trying to convey all the architectural features of the temple absolutely accurately. Accordingly, we have placed a window in this place in the model (see Figure 16).

Fig. 16. Placement of the window on the temple model in the Sketch Up program

Thus, the model of the temple was successfully brought to the roof. A light drum is installed on top of the roof. Eight semicircular windows, the base of the drum lined with bricks, as well as paired pilasters in the piers between the windows were reconstructed from a photograph of the dome taken from a height (see Figure 17), analogs and a postcard of pre-revolutionary time. 

Fig. 17. Photo of the dome of the Trinity Cathedral of the mid-twentieth century. Copy from the collections of the Togliatti Museum of Local Lore, 12.05.2022

According to the same photo (see Figure 21) the laterna placed on the dome of the drum was restored, as well as the cross completing the composition of the temple. The result of the restoration of the dome drum can be seen below (see Figure 18).

Fig. 18. A drum with a dome restored from photographs in the Sketch Up program

Separately from the temple, a 3D model of the narthex with a classical portico was created. First, we measured the length and width of the portico from photographs, as well as the distance between the columns, then created a stereobat of the appropriate size. The columns were created in the Tuscan style: from the wide base they gradually narrowed upwards. The portico ended with an entablature, the cornice of which is crowned with a triangular pediment with a tympanum (see Figure 19). Then the entire portico was assembled into a group and copied twice near the side walls of the temple. Thus, the western, northern and southern entrances were marked with the same design.

Fig. 19. 3 D-model of the entrance portico to the temple, created in the Sketch Up program

Description of the process of creating a model of the bell tower at the cathedral

The creation of a 3D model of the bell tower, as in the case of the temple, began with placing its photos in the field of the Sketch Up program and scaling them using data from a written source. In addition, we know exactly at what distance from the temple was the bell tower.Orlov says: "The bell tower at the temple is arranged separately from it at a distance of 4 fathoms (8.53 m - approx. author). The bell tower consists of two tiers, whose height to the spire is 11 fathoms and 2 yards (25 m – approx. author), the spire to the cross is 1 fathom and 1 arshin (2.83 m – approx. author), and the total height of the bell tower has up to 25 fathoms with two yards (55 m – approx. author). <...> The shape of the church is square, its length and width are 8 fathoms with a yard (18 m – approx. author)».

Thus, by applying Match Photo technology again (see Figure 20), we managed to bring the photos to the appropriate scale, with the help of which we will further find out the dimensions of certain elements of the bell tower.

Fig. 20. Application of the Match Photo function to the bell tower in the Sketch Up program. On Wednesday , a copy photo was imported from the collections of the Togliatti Museum of Local Lore

The problem with building a 3D model of the bell tower was that most of its photographs were of inadequate quality (highlights, blurring), and it is quite difficult to identify its decorative elements and the exact appearance of the window frames. However, after working with the My Heritage photo enhancement service and finding more photos of the bell tower from different angles and up close, using the aforementioned postcard, we managed to restore the appearance of all the problematic decorative elements.

For example, the northern wall of the bell tower looked like this (see Figure 21-22).

Fig. 21-22. Drawing the northern wall of the bell tower in the Sketch Up program. On the left is the postcard shown in Figure 16, on the right is a screenshot from the Sketch Up program

In the same way, the appearance of the window frame was restored, largely repeating the plastic of the cathedral, as it was said in the card of the object of historical and cultural heritage ^[30] (see Figure 23-24), but differing in smaller size.

Fig. 23-24. Drawing the window frame of the bell tower in the Sketch Up program. On the left is the postcard shown in Figure 16, on the right is a screenshot from the Sketch Up program

With the help of a photo of the temple on a pre-revolutionary postcard (see Figure 12) we also managed to make a virtual reconstruction of the chapel of the bell tower, the so-called St. Nicholas Church. It was warm, services were held in it (instead of the temple) in the cold season, as evidenced by the pipes on the roof. In general, it repeated the plasticity of the bell tower, the main entrance to the chapel is organized in the form of a narthex and a pseudo-portico, which, narrowing in plan towards the entrance, formed an expressive axial composition (see Figure 25).

Fig. 25. 3 D-model of the chapel of the bell tower (St. Nicholas Church), created in the Sketch Up program

Creating a texture database for building a model

It is known that the main materials of the cathedral were brick and plaster. However, in the process of research, we had a question: what color was the brick used in the construction of this cathedral? In the card of the monument of history and culture, stored in the Togliatti Museum of Local Lore, it is indicated that the material of the temple was white brick, while the archival source states: "It was a large and powerful building built of red, well-baked brick, about one and a half times larger in size than the current brick" ^[31]. Since most likely the card from the museum was compiled on the basis of photographs of the temple, the compilers made an assumption about the white color of the brick. Thus, in this matter, it was decided to trust information from an archival source. To make sure of our decision, we analyzed the photo of the pre-revolutionary time (see Figure 12) and photos of the middle of the XX century (see Figure 9), uploading them to neural networks that determine by various shades of gray in the photos. Thus, we have received another proof that the cathedral was red at first, and only later – white. It follows from this that the material was red brick and white plaster, as in the case of the analogue given earlier. (see Figure 6).

Therefore, the texture of white plaster was applied to the walls of the temple and the bell tower. Niches, columns and decorative ornaments of the temple were covered with a denser and slightly grayish type of plaster. The plinth of the temple and bell towers are covered with a texture of yellowish-gray plaster for the realism of the picture – as a rule, such places in buildings were not pure white.

The roof was covered with lead, the assumption about the roof material was made on the basis of the characteristic seams on the roof of the temple and the drum (see Figure 17) and analogues (see Figures 6, 7).  In addition, it was the most common material for the roofs of temples and churches in the XIX century.

These textures were collected into a single database, where textures of glass (for windows), gold (for apples, crosses and bells) and wood (for doors) were also added. Normal maps have been created for each texture, so that in the future, when importing into Twinmotion, you can work with the nature of textures, bringing the appearance of materials closer to realistic.

Methodology of terrain restoration

For high-quality visualization of the temple, we decided to place it in a special environment: the temple will be surrounded by buildings of official purpose, located next to it inside the fence.

To ensure the realism of this visualization, it is necessary to restore the approximate relief of this area. This is quite an interesting experience of using the 3D modeling method due to the terrain features of this region: according to sources ^{[11, p.203]}, even during the time of the Stavropol fortress, the coast was constantly washed away with water from the Kunya Volozhka, whose waters, especially in spring, were significantly raised by the Volga. Even after the relocation of the city and the rebuilding of the temple in a new place at the beginning of the XIX century, the coast continued to crumble. In addition, the terrain contains significant elevation differences.

At the initial stage, to restore the approximate appearance of the relief, topographic maps were taken for the periods closest to our study: the American topographic map of Syzran (see Figure 26) and a map of the area flooded by the Kuibyshev reservoir in the Ulyanovsk region in 1955 (see Figure 27).

Fig. 26. A fragment of the American map of Syzran. Resource http://www.monetonos.ru

27. Map of the area flooded by the Kuibyshev reservoir in the Ulyanovsk region in 1955. The resource is a place.com ^[16].

By bringing the maps to a general scale and superimposing them in Adobe Photoshop, we obtained fairly accurate information about the dynamics of the terrain in the Stavropol-on-Volga region. Also, with the help of the city plan for 1951 (see Figure 28), it was possible to establish the exact location of the temple in the city and, accordingly, its place on the resulting relief plateau.

Fig. 28. The plan of the city of Stavropol-on-Volga for 1951 Copy from the collections of the Togliatti Museum of Local Lore, 12.05.2022

Thus, by uploading the superimposed maps to the Sketch Up program, it was possible to outline the main elevation lines on topographic maps. Then, using the functionality of the program, we placed markers on different elevation lines, the height of which was equal to the height of the relief in this place.  So we got a height map.

Then the resulting drawing was imported into the Twinmotion program, where it was given volume: the water texture was applied on the water level line, the texture of hilly grassy terrain was applied to the relief (see Figure 29).

Fig. 29. The process of constructing a relief in the Twinmotion program

After that, using the Sculpting mode, we raised the relief to the height of the markers. Thus, a large-scale environment was designed with a river, the outlines of the Usolsky Mountains and the relief terrain on which the fortress city was located (see Figure 30).

Fig. 30. Terrain reconstructed from a topographic map in the Twinmotion program. The temple is located in the middle of the stage at the place marked on the 1951 plan

Virtual reconstruction of the territory surrounding the Trinity Cathedral

To successfully visualize the virtual reconstruction of the Trinity Cathedral, it was decided to create a 3D model of the surrounding cathedral space: the fence and the buildings inside it.

First of all, it was necessary to figure out what kind of fence surrounded the cathedral during the period we studied. If you refer to the postcard (see Figure 12), then you can see one type of fence, while in the photos of the mid-twentieth century (see Figure 20) a different type of fence is visible. Since the postcard belongs to the pre-revolutionary time, it was concluded that the fence had undergone changes by the middle of the twentieth century. Considering that we are creating a virtual reconstruction for the period of the mid-twentieth century, it was decided to create a 3D model of the fence based on photographs (see Figure 3 1-32)

Fig. 31-32. The process of creating a fence model in the Sketch Up program.On the left is a photo of the Trinity Cathedral, shown in Figure 22, on the right is a model in the Sketch Up program

We know that there were several buildings on the territory of the cathedral: they can be traced both in photographs of the pre-revolutionary period and in photos of the mid-twentieth century (see Figure 33-34).

Fig. 33-34. Buildings inside the fence of the temple, marked in photographs of the pre-revolutionary period and the middle of the twentieth century. Copies from the collections of the Togliatti Museum of Local Lore

Initially, it was assumed that a large building housed a second–grade school and rooms for students, and smaller buildings were outbuildings. However, it was established that the school was two-storied and was not located on the territory of the cathedral. This is evidenced by documents from the Scientific Archive of the Togliatti Museum of Local Lore: "In 1930, an agro-pedagogical college was opened on Korpusnaya Street in the building of a two-grade school, which through accelerated courses gave a diploma of a primary school teacher and an agronomist" ^[32]. Consequently, the building of the second-grade school was located not far from the cathedral, on Sobornaya Street (Korpusnaya), which means that all the buildings that we see in the photos had service functionality. Unfortunately, it is not possible to determine their exact purpose, but judging by the photo of the already destroyed cathedral (see Figure 3) and to the preserved unique newsreel frames ^[33], the buildings were there until the period of the mid-twentieth century that we are studying. Accordingly, it is necessary to place models of buildings on our visualization.

Thus, based on the photos, we managed to create 3D models of buildings located on the territory of the temple (see Figure 35).

Fig. 35. 3 D-models of outbuildings on the territory of the temple, created by

in the Sketch Up program

Visualization of the created three-dimensional reconstruction in the Twinmotion program

So, we have prepared 3D models of the temple, bell tower, terrain, surrounding buildings and fences. At this stage of the study, it was necessary to carry out the final visualization of the project.

In the field of the Twinmotion program, where there was already a project with a virtual reconstruction of the relief, models of a temple with a bell tower were also added and placed on the place where the temple stood according to the 1951 plan (see Figure 28).

Thanks to the scaled photographs, it was possible to calculate the distance at which the former school building and outbuildings were located from the temple. It was at this distance from the temple that these 3D models were placed in the virtual environment of Twinmotion. All buildings were surrounded by a fence, previously modeled in the Sketch Up program (see Figure 36).

Fig. 36. Initial placement of all created models in Sketch Up in the Twinmotion program

Next, it was necessary to work out the aspects of the project's realism. To do this, paths were drawn at the entrance to the temple territory, to the buildings inside, trees and other vegetation were placed. All this was carried out based on photographs of the mid-twentieth century. They show that the territory of the temple was quite spacious and open, with a minimum amount of vegetation. Around there are city streets with power lines, residential buildings in neighboring neighborhoods, the post office building is relatively close, but the temple itself is located in an open square.

There were city streets with country roads around the temple. In these places, like photographs, textures of mud, puddles and a trampled road were superimposed (see Figure 37-38).

Fig. 37-38. Comparison of the textures of the surrounding area in the photo of the mid-twentieth century and visualization in the Twinmotion program. Photo on the left is a copy from the collections of the Togliatti Museum of Local Lore. On the right – visualization in the Twinmotion program

According to the photos, the locations of electricity poles and trees on the territory of the temple are marked (see Figure 39-40).

Fig. 39-40. Placement on a virtual reconstruction of trees and poles conducting electricity. On the left – visualization in the Twinmotion program. On the right – a photo from the collections of the Togliatti Museum of Local Lore

As a result, we get angles identical to those in the photographs of the mid-twentieth century, achieving maximum proximity to reality (see Figure 41-42).

Fig. 41-42. Comparison of mid-twentieth century photography with visualization in the Twinmotion program. On the left is a photo from the collections of the Togliatti Museum of Local Lore. On the right – visualization in the Twinmotion program

Most likely, there were areas for parishioners to communicate on the territory of the temple, and, as a rule ^[34], they were located near the gate at the entrance to the temple, on both sides of them. We placed a couple of benches to the right and left of the entrance to the temple, and also enlivened the scene by placing models of moving people at the entrance to the temple and the bell tower, a dog guarding outbuildings, and birds circling high above the temple (see Figure 43-44).

Fig. 43-44. "Animating" the visualization scene by placing models of people, animals, benches in it

Earlier we quoted from a source where it was mentioned that there were burials on the territory of the Trinity Cathedral ^{[2, p.118]} of clergymen and famous people. Unfortunately, the sources do not provide accurate information about the number of burials, whose they were and how they looked. However, it would be incorrect to ignore this information when making a virtual reconstruction. We analyzed the appearance of typical tombstones in Russian cemeteries of the XIX-XX centuries from photographs and created 3D models of them, placing them on the final visualization from the side of the altar of the temple.

At this stage of the study, we described the process of creating a virtual reconstruction of the Trinity Cathedral in Stavropol-on-Volga. We analyzed and compared data from various sources, and also worked with analog churches. Certain problematic and controversial points were identified during the virtual reconstruction of some elements of the temple, as well as ways to solve them were described. As a result, 3D models of the temple, the bell tower and the surrounding area inside the fence were prepared. We have received a virtual environment ready for visualization and placement on the Internet and the exposition of the Togliatti Museum of Local Lore.

Preparation of research results for electronic publication and placement in the museum

At the final stage of our virtual reconstruction, when the model of the temple was already ready, placed in an interactive environment, the relief and background were worked out, it became necessary to create renderings that meet modern realities, convert them into appropriate formats and, taking into account the experience of predecessors, prepare them for placement in the exposition of the Togliatti Museum of Local Lore.

To visualize and present the resulting project, an MP4 overview video was created, as well as several panoramas in 360° format with the ability to view virtual reconstruction from different viewing points. In addition, an explanatory text to the video has been written, containing reference material about the history of the Trinity Cathedral. The materials were transferred to the Togliatti Museum of Local Lore and placed in the hall "Mayak" of the permanent exhibition "20th century: Stavropol-Togliatti". A more detailed description of the practical application of the results of this study is the subject of a separate author's article "The experience of using 3D reconstructions of cultural heritage objects in museum practice (on the example of the Trinity Cathedral in Stavropol-on-Volga)".

We express our deep gratitude and gratitude to the Municipal Budget Institution of Culture of the Togliatti city district "Togliatti Museum of Local Lore" and personally to the director of the museum Natalia Lankova for providing materials and consulting on the topic of the study.