Using virtual reality to teach history

Transcription

1 Using virtual reality to teach history Calin Neamtu 1, Radu Comes 1, Razvan Mateescu 2, Rares Ghinea 1, Filip Daniel 1 (1) Department of Design Engineering and Robotics, Technical University of Cluj-Napoca, bd.muncii ,Cluj-Napoca, , Cluj, Romania (2) National History Museum of Transylvania, Cluj, Str. C. Daicoviciu, no. 2, Cluj-Napoca, , Cluj, Romania, razvanmateescu@yahoo.com Abstract This paper presents an original method to develop virtual reality applications used in the process of teaching/learning ancient history. The virtual reality applications used in education are focused around various kinds of artifacts-models that are virtual endowed with different properties and metadata. The authors present the methods used for the recreation of these artifacts-models, using reverse engineering techniques. The case study presented in this paper is focused on the reconstruction of a Dacian forge discovered in Sarmizegetusa Regia. Real artifacts were digitized using laser scanners to obtain virtual copies that preserve the shape and texture of the real artifacts. Scanned artifacts are used in a virtual reality application to illustrate the inventory and the use of those artifacts. Keywords: 3D laser scanning, historical artefact, virtual reality 1 Introduction Balancing quality and quantity is one of the major challenges of the current education system (Cook, 2011), (Lakdawalla, 2002), for almost every field. There are currently no universal methods accepted that can be applied and provide the best results, but most experts agree that e- learning and education would benefit a lot from using virtual environment applications. Interactive teaching is the key to success for any school subject taught at any level be it primary, secondary or university (Gupta, 2010). History as a discipline of science is within the group that can benefit from the contribution of technology in the teaching process. Using virtual reality applications to teach history is not something new, currently there are many national and international applications that combine virtual reality and stereoscopic projection in the teaching process. The problem identified by the authors of this paper, and for which they are trying to come with solutions is to use virtual reality as a tool to support learning and researching activities in universities. Even if all the specifically interaction tools are used in such an application, it cannot exceed the status of an interactive game if it cannot provide information and experience similar to real life interaction within the simulated environment. Even if you use advanced 3D projection and sophisticated haptic devices, a virtual reality application can provide an experience close to the real life interaction only if the 3D virtual objects are accurate to the real life objects (Craig 2009). This paper presents an algorithm to develop a virtual reality application using engineering methods to generate the 3D models of different historical artifacts and assemble them into a virtual reality application.

2 304 University of Bucharest and "Transilvania" University of Brasov 2 Algorithm Used To Create A Virtual Reality Application The main purpose of this algorithm is to obtain digital artifacts that have a high fidelity. In the authors vision, a 3D model can be classified as high fidelity if the shape deviations from the original digitized artefact are less than 50 µm. A 3D model with this precision can be used in educational applications to support university/post-graduate studies or even in research. 3D models can generally be obtained in two ways: through 3D modelling or 3D scanning. Using 3D modelling computer software (the main method and most used) to generate 3D models that are significantly lower quality than 3D scanned models, since they don t retain the precise dimensions, the details and the real texture of the artifact. The standard texture mapping techniques of 3D models can be replaced using laser scanners that have a build-in texturing system. At the moment this system can provide the best results comparable with the standard mapping techniques, but with major time savings and the certainty of keeping identical details with the ones on the real artefact. The working methodology presented below involves the creation of a virtual reality application hosted on the Web, because of this the dimension of the 3D models in MB and polygons shouldn t be too high, to allow different devices to load the models in an acceptable period of time. Laser scanning is the only method that is accepted to digitize historical artifacts (without damaging their integrity), the disadvantage of the laser scanning method is that it generates large amounts of data (polygons, vertices and pixels), data that affect the size (in MB) of a 3D model. File size is directly proportional to the scanned area and the number of geometry and texture acquired. Phase 1 Artifact Digitization: in this phase the artifact is analysed to identify the optimal scanning method. The main factor in choosing the method of scanning is to find the optimal technique to protect the artifact. Phase 2 Artifact Reconstruction: if the artifact is fragmented or incomplete, it can be reconstructed using different modelling techniques. This step is optional and it s successful completion requires interdisciplinary teamwork between engineers, archaeologists, historians, architects and others. Phase 3 3D Model Optimization: this involves reducing the amount of data resulting from the scanning process. This optimization should be done depending on the destination and utility of the 3D model. For teaching and learning the 3D model should be highly optimized, and for research it should ensure the highest possible accuracy, ignoring the optimization. Phase 4 Metadata: in this phase all the information regarding each artifact is collected and structured, and it will be added to the 3D model in the virtual reality applications. Currently there are a number of metadata schemes that can be used to ensure compatibility with other virtual platforms and applications, authors recommend a simplified scheme based on the CARARE metadata scheme CARARE metadata schema (CARARE 2012): Heritage asset identification - basic information about the monument, historic building, archaeological landscape area, shipwreck, artifact, ecofact etc. Record information; Appellation (ID, name); Description; Designations; Conditions, Repository; References Digital resource these are digital resources (images, texts, videos, audio, 3D models) that provide sources of information about the monument, they are often digital representations of monuments or of parts of monuments: Record information; Appellation; Format; Subject; Spatial; Publication statement; Type; Description; Created; Provenance; Language; Link; Resource metadata location; Relations; Rights Relations relations of the monument, event or resource to other monuments, events, references or resources: Type of relation; Target of relation Activity events or activities that the monument has taken part in, such as: Creation, Field investigation; Research and analysis; Historical events, etc.

3 The 7 th International Conference on Virtual Learning ICVL Figure 21 Algorithm for developing VR application using 3D scanning artifact Record information basic information about the record: ID (the ID in the provider s system); Type; Source; Creation when created and by who; Date Update the date of the last update to the record and by who; Language (of the metadata record); Rights; Keywords. Rights information about the rights associated with the object, metadata and the digital surrogate being harvested into the service environment: Copyright; Access rights; Reproduction rights; License. Phase 5 Creating The Virtual Artifact : the virtual artifact is assembled together with metadata so that it can be used in any applications of virtual reality. Such virtual artifact consists of a 3D model that has the dimension the detail and the texture of the real artifact. These artifacts have attached a set of metadata that makes it possible to identify all the necessary data (the age to which it belongs, the material it was made of, the place where it was found, etc). Besides the set of metadata the 3D model is equipped with different elements such as actionreaction interaction, extractive interaction and immersive interaction. Phase 6 Creating The Virtual Environment: for a better understanding of the context and the ways it was used, the artifact can be placed in a virtual environment very similar to the real environment. Phase 7 Publishing The Application: the publication of these applications should be made to ensure safety and accessibility standards in e-learning. In terms of accessibility it is almost mandatory to ensure compatibility with tablets and smartphones.

4 306 University of Bucharest and "Transilvania" University of Brasov 3 Case Study To validate the algorithm, several applications of virtual reality were developed using CAD software, computer graphics and virtual reality. The application presented below aims to teach details about iron tools from the Dacian period. For this purpose the authors used a Dacian forge discovered by C. Daicoviciu at Sarmizegetusa. The forge had over 40 different iron tools. 3.1 Phase 1 Artifact Digitization Items that have been digitized in this stage were classified into: Smithing tools Smithing products (weapons, armours, tools, decorative elements) Pottery Scanning was performed using two types of laser scanner, the first one, a Kreon Zephyr was mounted on a CMM and the other a handheld scanner (VIUscan) capable of scanning texture with up to 25 µm accuracy. The artifact from Figure 2 was scanned with VIUscan. This scanner uses auto positioning sticky marks that are placed on the artifact. This allows the user to move the object, as well as move the scanner around the object while maintaining the proper geometry of the scanned model. a b c d Figure 22 Real objects (a and c) and digitized 3D models For small artifacts, narrow surfaces or those with many edges, that don t have enough surface area to apply the auto positioning marks it is optimal to place the artifact on a flat surface and place the positioning marks on that surface. After the surface has been scanned, the object is rotated so that the surface that was not scanned before can be acquired. After this the multiple scanned surfaces are exported to CAD softwares.

5 The 7 th International Conference on Virtual Learning ICVL Figure 23 Real objects and digitized 3D models The second type of scanner used to digitize the artifacts has been mounted on a portable CMM, this scanner doesn't need target positioning marks, but the artifact can no longer be moved until the scanning process is completed. Figure 24 3D scanning using Kreon Zephyr mounted on a CMM 3.2 Phase 2 Artifact Reconstruction In this phase several artifacts were reconstructed. Wooden handles were added to several tools. Fragmented pottery was reassembled and reconstructed. The Workshop was reconstructed from the footprint discovered by archaeologists and using digitized iron items (nails, spikes, hinges, staples and decorative elements). There are many CAD applications that can be used to join the multiple scanned surfaces. For those objects that have been partially or totally damaged or are incomplete, there are computer softwares, such as CATIA that can be used to reshape the damaged artifacts. This software has modules build specifically for artifact reconstruction such as Digitized Shape Editor, Quick Surface Reconstruction, Shape Sculptor and finally the scanned surfaces can be converted and imported in Generative Shape Design were everything can be shaped using computer aided design 3D modeling methods.

6 308 University of Bucharest and "Transilvania" University of Brasov 3.3 Phase 3 3D Model Optimization Depending on the settings of the scanner, the 3D model vertices and polygons count can be very diverse. There are some cases were the scanned artifact have millions vertices and polygons, for those 3D models it s required an optimization in order to process their surfaces in computer aided design applications. This optimization is done by filtering and refining the shape using different algorithms. Optimizing a scanned 3D model needs to be done using controlled environment so that the deviations of the 3D model to be as low as possible. CATIA has a built in deviation analysis function, so the initial and filtered surfaces can be compared with ease. Figure 25 Reconstruction of a Dacian forge and two hand tools The figure below represents an anvil, the 3D digitized model has 228,620 triangles, after applying various polygon reduction operations the model has been reduced to 4526 triangles (50 times less), but this optimization has visible effects on the overall shape and the details on the anvil. Figure 26 Optimization of an anvil

7 The 7 th International Conference on Virtual Learning ICVL Phase 4 Metadata The metadata sets used in the application of virtual reality were created based on the information provided by archaeologists. Metadata attached to each component were classified into two categories: general interest : Appellation (ID, name), Description, Designations, Creation, Historical events, Description, Created, Provenance, Language; information of scientific interest. The two types of metadata are available for both versions of the application: one for public and one for teaching/learning at university level. 3.5 Phase 5 Creating the Virtual Artifact Information extracted from metadata sets will be displayed as the following interactive elements: Audio sequences Videos Power Point Presentations Wikipedia links and other external links Because the main purpose of this virtual reality environment is to provide information to the user, when the user wants to receive them, the application has different buttons, such as Teach Me, and here we can provide different links to websites, to PowerPoint presentations or even add video clips. Using this system all the information related to an artifact can be gathered, bookmarked and shown when requested. Along this features the artifacts can be visualized using different transparency modes, they can be rotated, moved, zoomed in or even animated. The information open in a different layer and it can be scaled so that the user can interact with the artifact. 3.6 Phase 6 Creating the Virtual Environment In a more complex virtual environment such as the reconstruction of the Dacian forge, there must be added some additional features such as a landscape that would help the forge to blend in with the environment, for example a forest landscape. But for single artifacts it s enough to give the user the possibility to rotate the object, move it around, or move his vision around it, zoom in and out to check the details. In some situations, for a better understanding of the historical context, objects can be placed in the spots where they have been discovered. For further experimentation, artifacts that are used in a particular activity or artifacts that are from the same family can be added to collections. Using these collections, artifacts can be studied together for an easier comprehension of the connections Figure 27 Virtual artifact between them.

8 310 University of Bucharest and "Transilvania" University of Brasov Figure 28 Virtual environment 3.7 Phase 7 Publishing the Application To ensure that the application is easy to access, the application will be published online, users will have to download a 3D player in order to start the application. This application will provide the facility to use anaglyph projection or 3D stereo projection using NVidia 3DVision. 4 Conclusions Using scanning as a tool for generating 3D models used in virtual reality applications that focus on history is feasible and can be successful. 3D scanning generates a larger amount of data compared to 3D modeling but offers a higher degree of fidelity. Using methods to reduce polygons of a 3D model can reach a compromise on the size in MB and quality of a 3D model. Authors recommend the use of scanning for historical artifacts for applications that are used for teaching. The high degree of detail obtained from scanning is suited for research activities. Considering the particularities of virtual reality applications that focus on history, the authors have developed an algorithm for virtual reality application development using 3D scanned object. This algorithm was validated by creating stand-alone applications and web hosted applications. ACKNOWLEDGEMENT This paper was supported by the project "Progress and development through post-doctoral research and innovation in engineering and applied sciences PRiDE - Contract no. POSDRU/89/1.5/S/57083", project cofounded from European Social Fund through Sectorial Operational Program Human Resources References Glenn Cook (2011) Las-Vegas Review Journal available on line at Darius Lakdawalla (2002) - Quantity over Quality, Education Next, Fall 2002 / Vol. 2, No. 3, Gupta, Madan Lal (2010) Interactive teaching and learning by using student response systems. The International Journal Of Learning, 17 5: Alan B. Craig (2009) - Developing Virtual Reality Applications, Elsevier Inc. ISBN CARARE metadata schema available online at