1. Introduction
According to historical sources, Bosnia and Herzegovina as an independent state originated in the 11th century. However, in its territory have been found remains from ancient times, starting in the Neolithic age. Romans, Illyrians and many other nations left their traces in this strategically important region, where East meets West. Today we can admire cultural monuments belonging to different cultures that have been living and still live in this country. Four monotheistic religions have their houses of worship next to each other. Museums are rich with artefacts from important archaeological sites. However, some cultural heritage objects have disappeared. Time, wars and cultural neglect have erased them not only from the face of the Earth, but also from the collective memory of the people.
The digital age offers the possibility to recover these constructions in a virtual world. Digital technologies offer very efficient tools to display the original appearance of objects that at present exist only as remains at archaeological sites. Today we can virtually walk through magnificent monuments of ancient civilizations. Computer graphics provide powerful tools for the creation of high fidelity computer models, and computer animations are easily mistaken for captures of reality.
However, even the highest quality geometry will not evoke in the user the feeling of immersion in the past as does its combination with digital storytelling. Today, museum visitors are no longer content with physical exhibitions that do not offer more than labels next to the historical artefacts. People expect to see the reconstruction of the past and learn about the context of exhibits, their purpose and characters. Only then are they ready for time travel.
For ten years now, the Sarajevo Graphics Group from the Department of Computer Science at the Faculty of Electrical Engineering in Sarajevo has been creating interactive virtual presentations of cultural heritage objects, combining virtual environments with digital stories. User studies have shown that these presentations immerse the users such that they feel they are really inside the past. In this paper we will present the example of such an application to illustrate how to breathe life into three-dimensional (3D) geometry.
2. Previous Work
Storytelling has recently become an important part of cultural heritage presentations. Museum exhibitions introduce digital content to enhance their artefacts and attract more visitors, enabling them to learn about the history and context of the exhibits. Virtual reconstructions of cultural heritage objects incorporate various forms of storytelling.
The Etruscanning 3D projectReference Hupperetz, Carlani and Pletinckx 1 is a virtual presentation of the Regolini Galassi tomb, one of the most remarkable Etruscan graves, and the artefacts found in it. The application is permanently set up in the Allard Pierson Museum in Amsterdam, but, thanks to its digital nature, it has been traveling around many exhibition spaces. Digital content consists of a virtual model of the tomb with the models of artefacts found in it, which are currently kept in the Vatican Museum, as well as stories told by two narrators, characters buried in the tomb. The content is displayed on the projection screen and users browse and activate the stories through the natural interaction interface.
The European Network of Excellence ‘Virtual Museum Transnational Network V-MusT.net’ has been researching and synthesizing the knowledge on digital cultural heritage for four years (2011–2015). In its final exhibition ‘Keys to Rome’,Reference Pescarin 2 it showcased the virtual reconstructions of Roman heritage in four geographic locations (Rome, Amsterdam, Alexandria and Sarajevo) simultaneously. This multimedia exhibition aimed to present life in various parts of the Roman Empire during the era of Emperor Augustus. A combination of physical exhibitions from the four selected museums and digital content connected all locations through virtual heritage applications online. In one of the setups, called Admotum, the visitor, through a natural interaction user interface, walks through virtual models of buildings from the Roman period that used to exist in his/her location, following the stories about objects from those buildings (virtual models of museum artefacts found in the archaeological sites). After successfully collecting all objects in his/her location, the visitor can unlock the other three locations of the exhibition, collecting their objects, traveling through their monuments and learning about them from digital stories.
The Sarajevo Graphics group introduced digital storytelling for the first time in the virtual reconstruction of the Church of the Holy Trinity in Mostar,Reference Ramic-Brkic, Karkin, Sadzak, Selimovic and Rizvic 3 where the priest recorded on the green screen tells stories about the church while being incorporated in its virtual model. This church, a beautiful example of Orthodox architecture, was completely destroyed by Bosnian Croat military forces in 1992, leaving just stones. The purpose of the virtual reconstruction is to draw the attention of the public to this object and encourage its physical reconstruction.
The virtual reconstruction of Isa bey’s endowment was also enhanced with digital stories in various implementation forms,Reference Rizvić, Sadžak, El Zayat, Žalik, Rupnik and Lukač 4 such as interactive animation and interactive audio storytelling in a 3D virtual environment. Isa bey Ishakovic, the founder of Sarajevo, in 1462 built a tekke, 5 public kitchen and accommodation complex for public use. It was dedicated to travellers and Mevlevi dervishes. Today there is a road and gasoline station at this location. The goal of this project was to bring these objects, mentioned in the oldest written document about Sarajevo, back to public memory using interactive storytelling. Three-dimensional models of objects are incorporated in a real-time virtual environment. The surrounding terrain is constructed using a fractal terrain generation method. The user is guided through the environment by an interactive story. The story presents each recreated object and its purpose. Dervish rituals that were performed inside the tekke are presented by interactive computer animation. User evaluation shows the levels of immersion and presence felt by the visitors through qualitative user experience methodology. The user study results prove that the interactive storytelling is a better form of cultural heritage virtual presentation than the non-interactive form (movie).
Apart from these enhanced virtual reconstructions, we also introduced digital storytelling in our virtual museums. The Virtual Museum of Bosnian Traditional Objects presents, online, the collection of objects from the Museum of Sarajevo that were used in houses and shops through history.Reference Rizvic and Sadžak 6 Artefacts are presented by galleries of photos, interactive 3D models and digital stories. Through these stories virtual museum visitors can learn about the purpose of objects and their historical value.
In the Virtual Museum of the Bosniak Institute, the user is guided through collections by audio stories.Reference Šljivo 7 The individual collection artefacts are presented in the same way as in the previously mentioned virtual museum. User evaluation has shown that the stories guiding visitors through collections created such an immersion that they did not notice any limitation in movement in the 3D environment. In this virtual museum, the navigation is implemented through images with hot spots instead of real 3D, but it was not noticed by users, nor qualified as a disadvantage.
Digital storytelling as a navigation tool in virtual museums was particularly appreciated by the users in the case of our Sarajevo Survival Tools project.Reference Rizvic, Sadzak, Hulusic and Karahasanovic 8 This virtual museum is based on the collection ‘Sarajevo Under the Siege’ from the Historical Museum of Bosnia and Herzegovina, which contains objects created by Sarajevo citizens during the 3.5 years of siege imposed by Serb military forces from 1992 to 1996. The physical exhibition lacks information on the context of the war in Bosnia and Herzegovina, while the individual exhibits fail to communicate the atmosphere in the city during the siege. Each exhibit has its own story, as they are creative improvisations made for heating, lighting and generally surviving this horrible period in history. Our Virtual museum is structured in the following way: the main story starts with an introduction on the context of the siege and continues in the form of thematic stories about the actual living conditions of Sarajevo citizens (water, heating, food, etc). After each of these sub-stories the user can browse the interactive virtual exhibition with artefacts related to that topic. When clicking on an object in this exhibition, the system displays the 3D model of the object, a gallery of photos and its digital story. Three-dimensional models are interactive and lift the constraints of museum visits where the exhibits cannot be touched or turned around.
In the Tašlihan application, which we present in this paper, we continue our quest for the interactive digital storytelling method most appreciated by the users.Reference Rizvic 9
3. Tašlihan Application
The Tašlihan (Figure 1) was the largest accommodation facility in Sarajevo during the Ottoman period. It was built between 1540 and 1543 as an endowment of Gazi Husrev Bey, governor of the Bosnian province within the Ottoman Empire. The word endowment (waqf) comes from the Arabic verb ‘veqafe’ meaning to stop, detain, dedicate, and indicates that waqf property (the endowed property) is exempted from regular transactions in trade and is dedicated to other purposes. It is a material good that a person willingly donates in the name of God, while the revenues and the purpose of the waqf serve the public. The institution of the waqf or endowment is very old and rooted in Islamic tradition. It is a gift for the public, communal good, or the dispensing of wealth for the benefit of the community. In economic, cultural, and social terms, a waqf is a means to prosperity.
Figure 1 The Tašlihan displayed within the physical model of Sarajevo old town, Museum of Sarajevo, Brusa Bezistan department.
Gazi Husrev-bey was a famous benefactor of Sarajevo, the son of Ferhat bey and Seldzuka, daughter of Sultan Bayazid II. He dedicated all of his wealth to Sarajevo and its citizens, building monumental constructions and leaving them as endowment. Apart from the largest and most famous mosque in the Balkans, Gazi Husrev-bey’s mosque, he built a hamam (public bath), bezistan (covered market), Tašlihan, Kursumlija maddrasa (college), Hanikah (a sufi gathering place – tekke), a soup kitchen and a library. He also built 200 shops for the maintenance of the endowment, with shop owners committed to submit a percentage of their income for the purpose. This funding made possible the later construction of the clock tower, Morica han inn, and the first Sarajevo hospital.
In the Tašlihan, rooms for guests were positioned on the first floor around the square yard, with stables for horses beneath, and shops on the exterior side of the building. Next to the Tašlihan there was built a huge covered bazaar called Bezistan, with 52 shops. At present only one wall remains of the Tašlihan (Figure 2), within the Hotel Europe garden. The Bezistan still functions as a trade centre.
Figure 2 The only remaining wall of the Tašlihan.
Sarajevo citizens and the visitors to the city often pass by the Tašlihan location, but they are not aware of its original appearance. Virtual presentation, with its online and museum setup, has returned this magnificent object into collective memory.
3.1 Concept
The interactive virtual presentation of the Tašlihan is implemented in the Museum of Sarajevo and online.Reference Prazina 10 Taking into account the initial feedback from the users, we designed the presentation in three versions: documentary story, interactive digital story and serious game. This way we can compare the reactions of the users and explore the advantages and drawbacks of each presentation form. First, we created a high-quality 3D virtual model of the Tašlihan, in collaboration with experts, historians and the archaeologists who excavated the site. The geometry was created in Maya and exported to Unity 3D, where the basic navigation interface was added. The storytelling was designed according to our novel interactive digital storytelling methodology. The objectives of this methodology are to offer an innovative form of storytelling presentation adjusted to a concept familiar to the modern Internet era (hypertext), to optimize viewer’s time (stories can be viewed separately, as most of the users nowadays have no time for watching long videos), and to join different media in a unique digital storyline.
The story about the Tašlihan consists of the main story and sub-stories describing in detail selected topics mentioned in the main story (Figure 3). Based on the historic facts, a professional novelist wrote scenarios for the stories. He introduced a narrator, Murad bey Tardic (Figure 4), who was a friend of Gazi Husrev bey, and who is buried next to him in the yard of Gazi Husrev bey’s mosque. Murad bey tells us about the benefactor, the builder and the important events in the history of the Tašlihan.
Figure 3 Interactive digital storytelling structure.
Figure 4 The drawing of the narrator, Murad bey Tardic.
Facing the lack of video footage (the project had no funding and was carried out as a student’s work), we engaged a graphics designer to create drawings of the main characters from the story. Digital stories were edited as sequences of old photos, camera recordings, graphics illustrations and the Tašlihan model computer animation renders.
3.2 Implementation
After finalizing the digital stories and the interactive virtual model of the Tašlihan, we implemented three versions of the virtual presentation. The documentary story was a sequence of selected digital stories, ready for playback directly from YouTube. It was created upon a request from our screenwriter, who is not familiar with interactive 3D technologies and prefers to watch the story in a traditional way. We assumed there are other people who feel this way and decided to satisfy their needs as well.
The interactive digital story and the serious game are implemented in Unity 3D.Reference Prazina 10 The interactive digital story (Figure 5) starts with the main story representing a summary of the information about the monument, its history and related events and characters. It consists of seven thematic clusters. After each thematic cluster the user can activate the link to the sub-story, which describes in more detail the topic mentioned in the main story. One of the sub-stories is linked to the interactive virtual model of the object (Figure 6).
Figure 5 Interactive digital story, graphics user interface.
Figure 6 Tašlihan, interior yard, virtual reconstruction.
In order to explore whether users like watching an interactive story with incorporated 3D models or prefer to challenge their knowledge for a reward, we implemented this application as well as a serious game. The serious game has a similar concept to the interactive digital story, except for displaying the interactive virtual model. In this version, the model can be viewed only if the user replies correctly to questions related to the digital stories.Reference Rizvic and Prazina 11 In this way, the users pay more attention to the information conveyed in the stories and learn more about the monument and its history.
4. User Evaluation
The public promotion of the Tašlihan virtual reconstruction project has created a lot of attention in the Bosnian media and with the general audience. We have received many comments regarding how very useful people find this application, as they now discover an object whose remains they pass by every day without knowing what a great cultural monument used to exist in that place. Both Sarajevo citizens and visitors to the town claim they learned from our stories something they have not been able to learn any other way. They particularly appreciated the introduction of a narrator, Murad Bey Tardic, a friend and collaborator of Gazi Husref Bey, who added an emotional dimension to storytelling. This argues in favour of our hypothesis that storytelling breathes life into virtual cultural heritage reconstructions.
4.1. Customer Satisfaction Questionnaires
The initial evaluation of the project was done by nine users who filled out a customer satisfaction survey. The first group of questions was related to information perception. We have investigated what the users have learned from the application, asking them questions about the notions mentioned in the stories. We also evaluated the quality of the interactive digital storytelling, asking the users to mark the narrative, the video and music in the digital stories. The third group of questions concerned the interactive 3D model of the Tašlihan. First, we investigated if the users opened the model, as it is positioned as a link in one of the sub-stories. Then we inquired about the quality of the model’s geometry, textures and illumination, as well as the navigation through the model. The last group of questions considered the overall satisfaction of users, with an emphasis on feelings of immersion. The users could describe what they liked and disliked in the application. The questions, which contained rating of particular aspects of the project, were set up according to the positive response bias,Reference Kamakura and Mittal 12 so the users could rate the particular aspect from 1–10, but in case 9 or lower was chosen, they were offered the question ‘What would make it a 10’?
Although this initial evaluation was performed on the basis of an extremely small number of users, the results we obtained are very valuable. Most of the users rated the application and its particular aspects as 10 and felt immersed in the past of the Tašlihan object. More important was that they appreciated the concept of hyperlinked stories as a method to present the information on cultural heritage. One of them answered the question: ‘What did you like the best in the Tašlihan application?’ with: ‘“widening” of the story in the sense that the viewer who becomes interested in a particular part of the story has the possibility to further explore. Also, I have never seen something similar to this concept of mixing stories and 3D models in a unique interactive application, it’s a quite new experience for me’. Another said: ‘this is much better than reading a tourist guide’. Most of the users found as a drawback the long downloading time of the application, some of them would like to see a more detailed 3D model of the object, and one of them was missing people in the virtual environment. They also mentioned that some controls over the playback of the stories should be introduced.
4.2. Qualitative Data Analysis – Data Coding
One of the most efficient methods of user evaluation is the qualitative analysis of user feedback. It is based on interviews with the users in which they express their experience during the use of the application. This kind of user evaluation is performed according to the following workflow:
∙ definition of hypotheses,
∙ interviewing the users,
∙ data coding of user feedback,
∙ analysis of coded answers, and
∙ comparison with hypotheses.
Experiment design
The user experience practice has shown that seven users will find approximately 80% of problems of an interface or application.Reference Seaman 13 In our experiment, user selection included different nationalities (Spanish, Indian, Azeri, Chinese) and various academic backgrounds (computer scientists, historians, colour science students, etc). Five of them were experienced computer users. Their average age was 29.
Evaluation process and results
Qualitative data analysis is based on data coding.Reference Feng, Hochheiser and Lazar 14 It is a process of extracting qualitative data into quantitative form. The possible values of the qualitative data are created according to the given answers. Since participants often use different terms for the same notion or the same words for different notions, it is important to perform coding as accurate as possible, without losing too much information.
The data analysis was performed in two steps: defining the hypotheses and grounding the evidence. We defined the following hypothesis:
∙ H1: users learn more from interactive storytelling than from a linear story,
∙ H2: the interactive storytelling application makes users immersed in the past,
∙ H3: users prefer interactive over linear storytelling.
The hypotheses were generated using the constant comparison method.Reference Feng, Hochheiser and Lazar 14 After coding the questions (Table 1), each of them representing a particular section, we went through the data looking for patterns. At the end of the analysis we obtained the level of hypotheses confirmation presented in Table 2. These results show that we still have to work on the interactive digital storytelling methods in order to motivate the majority of users to choose it over the linear storytelling.
Table 1 Coding the questions.
Table 2 Hypotheses confirmation.
Finally, we will quote some of the user statements we find valuable for future research: ‘It supplies a 3D model that allows the user to get the feeling about the building. Compared with a normal presentation, makes the user involved with the environment’, and ‘The interactive form gives freedom to select the certain part of the information the participant would like to listen to again’, or ‘It is nice how information is displayed, the mixture of old images and 3D reconstruction. If I need to imagine, from the current picture of the site nowadays, how the building was before, it would not be possible for me.’
4.3. Interviews with Interdisciplinary Experts
Considering that virtual cultural heritage presentations are usually created by multidisciplinary teams and that they should satisfy the needs of all audience target groups, we decided to collect the opinions of different professionals about the Tašlihan project. A group of interdisciplinary experts (archaeologist, art historian, historian, mathematician, computer scientist) evaluated our application during a meeting of the COSCH 15 project. Through customer satisfaction questionnaires and interviews they supplied their comments and recommendations.
Their evaluation can be summarized as follows. They expressed no doubt that storytelling can breathe life into virtual cultural heritage presentations. In the case of the Tašlihan project, they appreciated the interactive storytelling concept, story scenarios and characters, virtual reconstruction of the object and the voice of the narrator. As minor suggestions, they recommended the introduction of narration in English instead of subtitles for the digital stories. They considered it useful to add annotations to the interactive 3D model of the Tašlihan monument. Some of them remarked that the historical context is missing. They recommended using professional actors in stories. The application should be more fun for younger users and some dramatization could be added. All of them appreciated interactive storytelling over a linear one.
5. Conclusions
Our experience shows that virtual cultural heritage reconstructions become more appreciated by the users if they contain digital storytelling. The user immersion increases if storytelling is crafted by a skilled professional writer. Still, a lot of work remains to develop the best form of interactive digital storytelling presentation in order to obtain the maximum user satisfaction. There is a trade-off between the amount of interaction and the amount of conveyed information. We are still evaluating if the users prefer an interactive virtual environment with stories linked to some triggers or a storytelling structure with hyperlinked interactive virtual models. However, regardless of the presentation form, we can conclude that storytelling can breathe life into cultural heritage 3D reconstructions.
Selma Rizvić is an Associate Professor at the Faculty of Electrical Engineering Sarajevo (ETF) and founder of the Sarajevo Graphics Group (SGG). She also works as visual artist and Head of Broadcast Design Department at BH Radio Television. Her scientific interests are Computer Graphics, Computer Animation, Broadcast Graphics, Virtual Heritage and Digital Storytelling. Currently she is involved in MPNS COST Action TD1201 ‘Colour and Space in Cultural Heritage’ (COSCH). Until January 2015 she was a coordinator for ETF in the FP7 Network of Excellence 270404: V-MusT.net – Virtual Museum Transnational Network. She and her colleagues from SGG introduced the research of digital technologies application in cultural heritage preservation and presentation in Bosnia and Herzegovina. They created a number of virtual cultural heritage projects, the most famous of them being the Sarajevo Survival Tools, virtual museum of the Sarajevo siege. More details can be found at http://people.etf.unsa.ba/~srizvic/.
