Walking among Mammoths. Remote Sensing and Virtual Reality Supporting the Study and Dissemination of Pleistocene Archaeological Sites: the Case of Fuente Nueva 3 in Orce, Spain

sustainability Article Walking among Mammoths. Remote Sensing and Virtual Reality Supporting the Study and Dissemination of Pleistocene Archaeological Sites: The Case of Fuente Nueva 3 in Orce, Spain Juan Francisco Reinoso-Gordo 1,* , Deborah Barsky 2,3 , Alexia Serrano-Ramos 4, JoséAntonio Solano-García5, Carlos Alberto León-Robles 1, Carmen Luzón-González 4, Stefania Titton 2,3 and Juan Manuel Jiménez-Arenas 6,7,8,* 1Departamento Expresión Gráfica Arquitectónica y en la Ingeniería, Universidad de Granada, 18071 Granada, Spain; [email protected] 2Institut Catalàde Paleoecologia Humana i EvolucióSocial, 43007 Tarragona, Spain 3Departament d’Historia i Historia de l’Art, Universitat Rovira i Virgili, 43002 Tarragona, Spain; [email protected] (D.B.); [email protected] (S.T.) 4Programa de Doctorado de Historia y Artes, Universidad de Granada, 18071 Granada, Spain; [email protected].es (A.S.-R.); [email protected] (C.L.-G.) 5Departamento de Prehistoria y Arqueología, Universidad de Sevilla, 41004 Sevilla, Spain; [email protected] 6Departamento de Prehistoria y Arqueología, Universidad de Granada, 18071 Granada, Spain 7Instituto Universitario de la Paz y los Conflictos, Universidad de Granada, 18071 Granada, Spain 8Department of Anthropology, University of Zürich, CH- 8057 Zürich, Switzerland *Correspondence: [email protected] (J.F.R.-G.); [email protected] (J.M.J.-A.) Received: 10 May 2020; Accepted: 6 June 2020; Published: 11 June 2020   Abstract: Remote sensing is a useful tool for the documentation of archaeological sites. The products derived from a photogrammetric project applied to archaeology such as orthophotos and three-dimensional virtual reconstruction (3DVR), allow for detailed study of the Fuente Nueva 3 site in Orce. In our study of the Fuente Nueva 3 site in Orce, we used 3DVR intensively to map out the morphometric features of mammoth tusks exposed on the surface and a geological fault affecting the site’s deposits. To do so, we used imagery captured since 2017 in order to follow the evolution of ongoing excavations during each subsequent field season. We also integrated the 3DVR model in a videogame environment, to create a virtual reality (VR) that allows a VR navigation experience around the scenario using a head mounted display like Oculus Rift. The main features of this VR experience are: (1) It is ideal for the diffusion of archaeological contents since it permits an attractive presentation mode thanks to stereo visualization and realistic immersion sensations; (2) it provides a high level of detail all along the navigation experience, without incurring any damage to the archaeological remains; (3) it allows users to observe more details than they would in an in situ visit to the site; (4) it makes it possible to convert an archaeological site into portable heritage, opening up the possibility to extend visits to vulnerable groups: specifically those with reduced mobility. Our results show that using VR should permit enhancements to a visitor’s experience and contribute to the socio-economic development of the town of Orce, one of the Spanish municipalities with the lowest income. Keywords: Pleistocene heritage site; visitor attraction; photogrammetry; immersive virtual reconstruction; videogame Sustainability 2020,12, 4785; doi:10.3390/su12114785 www.mdpi.com/journal/sustainability Sustainability 2020,12, 4785 2 of 19 1. Introduction Because archaeological excavation is considered as a destructive procedure, it is critical to document each different stage of an intervention in the most reliable way possible. A final objective should be to generate a comprehensive corpus of data that allows reconstruction of the entire archaeological excavation process. Therefore, since the first attempts to include three-dimensional virtual reconstruction (3DVR) as an integral part of the archaeological field work routine at the beginnings of the 1990s [ 1 ], this method has now been converted into a key strategy, especially now that the costs of applying it have decreased. For these reasons, 3DVR has become a very useful and extensively used tool in archaeology, especially in those prehistoric sites containing architectural structures [ 2 – 5 ]. It is also a useful tool with which to evaluate damage suffered by an archaeological site [ 6 ], to assess and monitor the progress of excavations in different kinds of archaeological site contexts [ 7 ], to reconstruct cave sites that have yielded evidence of a human presence [ 8 – 10 ], and to reconstruct even the most ancient of human structures [ 11 ]. However, up to now, 3DVR techniques have not commonly been used to study open-air sites dating to the Pleistocene. The main reason for this is the weak impact that the activities of Pleistocene humans had, either on or below the ground. Nevertheless, very recently, 3DVR has been applied to reconstruct the context of a flint workshop area from an Italian Gravettian site [ 12 ]. Kruger and colleagues [ 10 ] have recorded and reconstructed the distribution of the paleoanthropological material at Rising Star cave, which includes the iconic hominin fossils of Homo naledi. It is commonly accepted that heritage management rests on three fundamental pillars: research, conservation and dissemination (or education) [ 13 ]. The inter-relational flows of these three key aspects of heritage are illustrated in Figure 1. Until about 30 years ago, researchers, restoration experts and visitors could only work and/or feel the experience of heritage by the means of direct sensorial contact with the physical artefacts/structures. Nevertheless, virtual reality (VR) provides new ways to research [ 14 ], restore [ 15 ] and disseminate [ 13 ] different kinds of heritage. In particular, VR has had a profound impact on dissemination. Today, visits to emblematic archaeological sites are very common and some of these now offer a double experience to users of VR: firstly, regarding the visit itself, which takes place using a product of real virtuality (RV) (e.g., the Lascaux IV neo-cave) and secondly, enhancing the experience with virtual reality (VR) tools (https://www.lascaux.fr/en). This combination , far from being redundant, becomes very attractive for visitors because both experiences are complementary [ 16 ]. In addition, the second application invites visitors to make their own decisions [ 17 ]. This may be related with a question pointed out by D. Haraway several decades ago: “Another critical aspect of the social relations of the new technologies is the reformulation of expectations, culture, work ( . . . )” [ 18 ] (p. 518). Also, our progressive approach to a cyborg-type conditioning of (hybrids between humans and machines) [ 18 ] implies that the use of these kinds of tools now lends, a fortiori, a more attractive experience to the public experiencing cultural heritage. Nevertheless, both VR and RV have to deal with objectives leading to resolve heritage questions that include, as we have said before, research, conservation and dissemination of scientific results. VR and RV are not, therefore, ends in themselves, but rather they are tools that contribute to a better understanding of the past [19]. Immersive virtual reality (IRV) is a very successful tool that combines aspects of VR and RV. Following [ 17 ] (p. 57), ‘immersive’ “ . . . refers to the degree to which a virtual environment submerges the perceptual system of the user in computer-generated stimuli” becoming an extension of body and mind. IRV creates effects and perceptions that do not require previous knowledge of the users to enjoy experiences that open the doors of spaces, such as archaeological excavations, allowed only to professionals. Sustainability 2020,12, 4785 3 of 19 Sustainability 2020, 12, x FOR PEER REVIEW 3 of 20 Figure 1. Flows among the different aspects of heritage management. Immersive virtual reality (IRV) is a very successful tool that combines aspects of VR and RV. Following [17] (p. 57), ‘immersive’ “…refers to the degree to which a virtual environment submerges the perceptual system of the user in computer-generated stimuli” becoming an extension of body and mind. IRV creates effects and perceptions that do not require previous knowledge of the users to enjoy experiences that open the doors of spaces, such as archaeological excavations, allowed only to professionals. On the other hand, heritage contributes to local socioeconomic development [20], a question that is especially relevant in low income regions. In this sense, it is worth noting that Orce is a small village located in the Huéscar Region of Spain (also known as the Altiplano of Granada) with a total of 1198 inhabitants [21]. This number reflects the strong population decline after 1950, when there were 4466 inhabitants. Moreover, the disposable income in 2017 was 12,894 €, ranking 2757th out of 2897 municipalities of >1000 inhabitants in Spain (range of disposable income: 53,185–10,584 €) [22]. Nevertheless, its Lower Pleistocene heritage makes Orce a place with good potential for the development of cultural tourism. Finally, the relationship between heritage and identity and even self-esteem constitutes another important issue [23]. Identity and self-esteem are “something actively and continually recreated and negotiated as people, communities and institutions reinterpret, remember and reassess the meaning of the past in terms of the social, cultural and political needs of the present” [23] (p. 83). To a certain extent, a community's self-esteem depends on its place in history and the recognition of the others. Additionally, having an original experience that distinguishes Orce from other similar cultural products in the area can lead to an increase in the number of visitors. In general terms, these users choose to incorporate not only the archaeo-paleontological aspect into their heritage experience, but also a peculiar gastronomic offer and unique accommodation in cave-houses. In this sense, it is important to point out that all the businesses in Orce are managed by people who were born or live in the town. Therefore, the impact of the visits on the local economy is direct. The positive impact of new developments related to cultural heritage is very great in such sparsely populated areas with such a low income. An example is the Museo “Primeros Pobladores de Europa” ("First Settlers of Europe" museum) which increased the number of visits, especially from 2015, from the year the new building was opened (Table 1). Figure 1. Flows among the different aspects of heritage management. On the other hand, heritage contributes to local socioeconomic development [ 20 ], a question that is especially relevant in low income regions. In this sense, it is worth noting that Orce is a small village located in the Hu é scar Region of Spain (also known as the Altiplano of Granada) with a total of 1198 inhabitants [ 21 ]. This number reflects the strong population decline after 1950, when there were 4466 inhabitants. Moreover, the disposable income in 2017 was 12,894 € , ranking 2757th out of 2897 municipalities of >1000 inhabitants in Spain (range of disposable income: 53,185–10,584 € ) [ 22 ]. Nevertheless, its Lower Pleistocene heritage makes Orce a place with good potential for the development of cultural tourism. Finally, the relationship between heritage and identity and even self-esteem constitutes another important issue [ 23 ]. Identity and self-esteem are “something actively and continually recreated and negotiated as people, communities and institutions reinterpret, remember and reassess the meaning of the past in terms of the social, cultural and political needs of the present” [ 23 ] (p. 83). To a certain extent, a community’s self-esteem depends on its place in history and the recognition of the others. Additionally, having an original experience that distinguishes Orce from other similar cultural products in the area can lead to an increase in the number of visitors. In general terms, these users choose to incorporate not only the archaeo-paleontological aspect into their heritage experience, but also a peculiar gastronomic offer and unique accommodation in cave-houses. In this sense, it is important to point out that all the businesses in Orce are managed by people who were born or live in the town. Therefore, the impact of the visits on the local economy is direct. The positive impact of new developments related to cultural heritage is very great in such sparsely populated areas with such a low income. An example is the Museo “Primeros Pobladores de Europa” ("First Settlers of Europe" museum) which increased the number of visits, especially from 2015, from the year the new building was opened (Table 1). Table 1. Museo “Primeros Pobladores de Europa” (Orce, Granada, Spain). Number of visitors and rate of increase (Source: Orce Town Hall). 2013 2014 2015 2016 2017 2018 2019 Number of visitors 2035 2402 3172 3932 3389 3616 4769 Rate of increase 18% 32% 24% − 16% 6.7% 31.9% Sustainability 2020,12, 4785 4 of 19 1.1. The Orce Archaeological Zone The Orce Archaeological Zone is located at the northeastern extremity of the Guadix-Baza Basin (Figure 2). The extant landscape is dominated by deep gorges and ravines with a vegetation typical of arid climatic areas. However, the landscape was very different during the Lower Pleistocene due to the presence of a large lake that conditioned life in the Guadix-Baza Basin. The Orce Archaeological Zone presently encompasses at least 15 different Pleistocene localities that have yielded fossils of extinct mammals [ 24 ]. Among these, three sites stand out for their richness in paleontological and archaeological heritage: Venta Micena (VM), Barranco León (BL) and Fuente Nueva 3 (FN3). Sustainability 2020, 12, x FOR PEER REVIEW 4 of 20 Table 1. Museo “Primeros Pobladores de Europa” (Orce, Granada, Spain). Number of visitors and rate of increase (Source: Orce Town Hall). 2013 2014 2015 2016 2017 2018 2019 Number of visitors 2035 2402 3172 3932 3389 3616 4769 Rate of increase 18% 32% 24% −16% 6.7% 31.9% 1.1. The Orce Archaeological Zone The Orce Archaeological Zone is located at the northeastern extremity of the Guadix-Baza Basin (Figure 2). The extant landscape is dominated by deep gorges and ravines with a vegetation typical of arid climatic areas. However, the landscape was very different during the Lower Pleistocene due to the presence of a large lake that conditioned life in the Guadix-Baza Basin. The Orce Archaeological Zone presently encompasses at least 15 different Pleistocene localities that have yielded fossils of extinct mammals [24]. Among these, three sites stand out for their richness in paleontological and archaeological heritage: Venta Micena (VM), Barranco León (BL) and Fuente Nueva 3 (FN3). VM, an open-air paleontological site, is the oldest one of these. During excavations carried out in 1982, a small skull fragment (VM-0) was identified as human [25]. Although subsequently this taxonomic attribution was challenged [26], this removes nothing from the importance of the VM paleontological site, which remains emblematic for the European Lower Pleistocene [27]. The VM site, dated to 1.6 Ma [28], is well-known for the quantity and quality of the fossil record it contains, providing very complete remains of extinct mammals. In 2002, the BL open-air archaeological site yielded a hominin deciduous lower molar, making it the oldest site in Europe with human remains [29]. In addition, the BL site provides one of the richest Oldowan lithic tool assemblages presently known in Eurasia (2799 elements up to and including the 2019 field season) [30–32]. In general terms, much of the lithic assemblage is comprised of large-sized used and knapped cobbles of Jurassic limestones. The assemblage also contains numerous smaller sized flint flakes and cores. Although the fossil remains are very fragmented, the macro-vertebrate assemblage from BL is very similar to that from VM and, especially, from the nearby site of FN3 (see below). The majority of the archaeological record was collected from sublevels D1 (where the human tooth was discovered) and D2, dated to 1.4 Ma [33]. 1.2. A Closer Look to Fuente Nueva 3 Archaeological Site FN3 is another open-air archaeo-paleontological site, located at the Orce Archaeological Zone (Figure 2). The site was discovered coincidentally in 1991, during works undertaken to install an electrical line. Since then, FN3 has yielded one of the oldest and most significant Oldowan stone tool assemblages so far discovered outside of Africa. Figure 2. Orce location in the province of Granada (Spain). Figure 2. Orce location in the province of Granada (Spain). VM, an open-air paleontological site, is the oldest one of these. During excavations carried out in 1982, a small skull fragment (VM-0) was identified as human [ 25 ]. Although subsequently this taxonomic attribution was challenged [ 26 ], this removes nothing from the importance of the VM paleontological site, which remains emblematic for the European Lower Pleistocene [ 27 ]. The VM site, dated to 1.6 Ma [ 28 ], is well-known for the quantity and quality of the fossil record it contains, providing very complete remains of extinct mammals. In 2002, the BL open-air archaeological site yielded a hominin deciduous lower molar, making it the oldest site in Europe with human remains [ 29 ]. In addition, the BL site provides one of the richest Oldowan lithic tool assemblages presently known in Eurasia (2799 elements up to and including the 2019 field season) [ 30 – 32 ]. In general terms, much of the lithic assemblage is comprised of large-sized used and knapped cobbles of Jurassic limestones. The assemblage also contains numerous smaller sized flint flakes and cores. Although the fossil remains are very fragmented, the macro-vertebrate assemblage from BL is very similar to that from VM and, especially, from the nearby site of FN3 ( see below ). The majority of the archaeological record was collected from sub-levels D1 (where the human tooth was discovered) and D2, dated to 1.4 Ma [33]. 1.2. A Closer Look to Fuente Nueva 3 Archaeological Site FN3 is another open-air archaeo-paleontological site, located at the Orce Archaeological Zone (Figure 2). The site was discovered coincidentally in 1991, during works undertaken to install an electrical line. Since then, FN3 has yielded one of the oldest and most significant Oldowan stone tool assemblages so far discovered outside of Africa. Two distinct archaeostratigraphic units compose the site’s depositional sequence: the Lower Unit (levels 1–4) and the Upper Unit (levels 5 to 12) [ 34 ] (Figure 3). Most of the archaeo-paleontological evidence comes from levels 3 and 5. In addition, the FN3 site has provided an age of 1.19 ± 0.21 Ma by the method of 230Th/234U [ 33 ], in agreement with the paleomagnetic analysis and the biostratigraphic evaluations [ 34 – 36 ]. From a lithological point of view, the predominant sedimentary materials are clays, Sustainability 2020,12, 4785 5 of 19 mudstones and limestones (Figure 3) [ 34 ]. A geological fault revealed during ongoing excavations extends in an east-westerly direction along the site. Sustainability 2020, 12, x FOR PEER REVIEW 5 of 20 Two distinct archaeostratigraphic units compose the site’s depositional sequence: the Lower Unit (levels 1–4) and the Upper Unit (levels 5 to 12) [34] (Figure 3). Most of the archaeopaleontological evidence comes from levels 3 and 5. In addition, the FN3 site has provided an age of 1.19 ± 0.21 Ma by the method of 230Th/234U [33], in agreement with the paleomagnetic analysis and the biostratigraphic evaluations [34–36]. From a lithological point of view, the predominant sedimentary materials are clays, mudstones and limestones (Figure 3) [34]. A geological fault revealed during ongoing excavations extends in an east-westerly direction along the site. Figure 3. Stratigraphic levels of Fuente Nueva 3[34]. Following the latest revision of the lithic assemblage, the FN3 collection contains 1630 pieces made from local limestone and flint, all of which were collected from systematic excavations ongoing at the site since 1994 [37,38]. The FN3 toolkit is well-preserved overall, and its numerical significance is outstanding for this timeframe in Eurasia. These factors contribute to the fact that this assemblage provides a complete sample from which to evaluate the cognitive and technological capacities of the first inhabitants of Western Europe. At FN3, Oldowan lithics are found associated with a rich faunal record. The complete list of large mammals is composed by the following taxa [39]: Order Carnivora Lynx sp. Felidae indet. Pachycrocuta brevirostris Lycaon lycaonoides Canis mosbachensis Vulpes cf. V. praeglacialis Ursus sp. Pannonictis sp. Meles meles Mustelidae indet (small size) Order Proboscidea Mammuthus meridionalis Order Perissodactyla Stephanorhinus hundsheimensis Equus altidens E. sussenbornesis Figure 3. Stratigraphic levels of Fuente Nueva 3 [34]. Following the latest revision of the lithic assemblage, the FN3 collection contains 1630 pieces made from local limestone and flint, all of which were collected from systematic excavations ongoing at the site since 1994 [ 37 , 38 ]. The FN3 toolkit is well-preserved overall, and its numerical significance is outstanding for this timeframe in Eurasia. These factors contribute to the fact that this assemblage provides a complete sample from which to evaluate the cognitive and technological capacities of the first inhabitants of Western Europe. At FN3, Oldowan lithics are found associated with a rich faunal record. The complete list of large mammals is composed by the following taxa [39]: Order Carnivora Lynx sp. Felidae indet. Pachycrocuta brevirostris Lycaon lycaonoides Canis mosbachensis Vulpes cf. V. praeglacialis Ursus sp. Pannonictis sp. Meles meles Mustelidae indet (small size) Order Proboscidea Mammuthus meridionalis Order Perissodactyla Stephanorhinus hundsheimensis Equus altidens E. sussenbornesis Sustainability 2020,12, 4785 6 of 19 Order Artiodactyla Hippopotamus antiquus Bison sp. Ammotragus europaeus Hemitragus cf. H. albus Praemegaceros cf. P. verticornis Metacervocerus rhenanus Additionally, FN3 provides a rich microvertebrate assemblage including: four amphibians, nine reptiles, one cyprind [40], six rodents, two lagomorphs and five insectivores [41]. Structurally, two different elements stand out in the FN3 site: a pair of exceptionally large-sized M. meridionalis tusks (Figure 4) and the (above-mentioned) geological fault. These two elements ( which may be considered as pseudo-structures) are challenging the continuity of the excavation process. Taken together, the significance of the FN3 site and the presence of these two remarkable elements are the focus of the present paper, which aims (1) to reconstruct these two significant elements being an intrinsic part of the site; (2) to extend the reconstruction to include and visualize the entirety of the excavation surfaces of FN3; (3) to provide the most reliable measurements of the M. meridionalis tusks, and (4) to create a video game (from VR to RV) as a tool to disseminate one of the most ancient site contexts with human presence presently known in Western Europe. Sustainability 2020, 12, x FOR PEER REVIEW 6 of 20 Order Artiodactyla Hippopotamus antiquus Bison sp. Ammotragus europaeus Hemitragus cf. H. albus Praemegaceros cf. P. verticornis Metacervocerus rhenanus Additionally, FN3 provides a rich microvertebrate assemblage including: four amphibians, nine reptiles, one cyprind [40], six rodents, two lagomorphs and five insectivores [41]. Structurally, two different elements stand out in the FN3 site: a pair of exceptionally large-sized M. meridionalis tusks (Figure 4) and the (above-mentioned) geological fault. These two elements (which may be considered as pseudo-structures) are challenging the continuity of the excavation process. Taken together, the significance of the FN3 site and the presence of these two remarkable elements are the focus of the present paper, which aims (1) to reconstruct these two significant elements being an intrinsic part of the site; (2) to extend the reconstruction to include and visualize the entirety of the excavation surfaces of FN3; (3) to provide the most reliable measurements of the M. meridionalis tusks, and (4) to create a video game (from VR to RV) as a tool to disseminate one of the most ancient site contexts with human presence presently known in Western Europe. Figure 4. Geographical situation and published ages of selected Oldowan, Early Acheulian and Large Flake Acheulian sites from Western Eurasia during the late Early Pleistocene (modified after [42]). 2. Materials and Methods The FN3 site is geo-referenced in the Spanish official reference coordinate system ETRS89 UTM Zone 30, also expressed in a local coordinate system (LCS) where the origin (X = 0, Y = 0, Z = 0) is very close to the excavation area (Figure 5). The LCS divides the excavation area into square-meters, where the X axis is denoted by letters and the Y axis by numbers (each in ascending order per 1 m squares). The present extension of the FN3 archaeological site is of 13 × 13 m (Figure 5). Figure 4. Geographical situation and published ages of selected Oldowan, Early Acheulian and Large Flake Acheulian sites from Western Eurasia during the late Early Pleistocene (modified after [42]). 2. Materials and Methods The FN3 site is geo-referenced in the Spanish official reference coordinate system ETRS89 UTM Zone 30, also expressed in a local coordinate system (LCS) where the origin (X =0, Y =0, Z =0) is very close to the excavation area (Figure 5). The LCS divides the excavation area into square-meters, where the X axis is denoted by letters and the Y axis by numbers (each in ascending order per 1 m squares). The present extension of the FN3 archaeological site is of 13 ×13 m (Figure 5). Sustainability 2020,12, 4785 7 of 19 Sustainability 2020, 12, x FOR PEER REVIEW 7 of 20 Figure 5. Horizontal plan of Fuente Nueva 3. The surface from the excavation area has been modeled in 3D imagery and its corresponding texture is derived from a photogrammetric process, so that the resulting product provides a very detailed documentation from the site. This methodology was carried out during the 2017 and 2019 field seasons, and is planned to continue in the future, in order to generate a temporal series showing in 3D the evolution of the excavation according to the research project goals, specifically those related to the spatial relationships between human-made lithic tools and vertebrate fossil remains. The 3D textured model can also be used to create scenarios that include realistic environments in virtual, where both the public and the researchers can interact with the remains discovered during each excavation campaign. The photogrammetry was carried out using two different approaches for the campaigns 2017 and 2019. In 2017, we used a Sony Alpha 5000 camera suspended on a pole, in order to achieve a vertical image. From a heritage conservation point of view, this procedure was inconvenient because it required a person to tread on the excavation surface, thus risking to inadvertently damage some of the remains. For this reason, in 2019, we decided to perform the photography using a remotely piloted aerial system (RPAS) (Parrot Anafi). This micro aerial vehicle was small enough so that its air flow does not affect the surface of the excavation. The above-mentioned set of camera, pole and RPAS are shown in Figure 6. Figure 6. Camera Sony Alpha 5000 hanged on a pole and remotely piloted aerial system (RPAS) used in the field seasons 2017 and 2019. Figure 5. Horizontal plan of Fuente Nueva 3. The surface from the excavation area has been modeled in 3D imagery and its corresponding texture is derived from a photogrammetric process, so that the resulting product provides a very detailed documentation from the site. This methodology was carried out during the 2017 and 2019 field seasons, and is planned to continue in the future, in order to generate a temporal series showing in 3D the evolution of the excavation according to the research project goals, specifically those related to the spatial relationships between human-made lithic tools and vertebrate fossil remains. The 3D textured model can also be used to create scenarios that include realistic environments in virtual, where both the public and the researchers can interact with the remains discovered during each excavation campaign. The photogrammetry was carried out using two different approaches for the campaigns 2017 and 2019. In 2017, we used a Sony Alpha 5000 camera suspended on a pole, in order to achieve a vertical image. From a heritage conservation point of view, this procedure was inconvenient because it required a person to tread on the excavation surface, thus risking to inadvertently damage some of the remains. For this reason, in 2019, we decided to perform the photography using a remotely piloted aerial system (RPAS) (Parrot Anafi). This micro aerial vehicle was small enough so that its air flow does not affect the surface of the excavation. The above-mentioned set of camera, pole and RPAS are shown in Figure 6. Sustainability 2020, 12, x FOR PEER REVIEW 7 of 20 Figure 5. Horizontal plan of Fuente Nueva 3. The surface from the excavation area has been modeled in 3D imagery and its corresponding texture is derived from a photogrammetric process, so that the resulting product provides a very detailed documentation from the site. This methodology was carried out during the 2017 and 2019 field seasons, and is planned to continue in the future, in order to generate a temporal series showing in 3D the evolution of the excavation according to the research project goals, specifically those related to the spatial relationships between human-made lithic tools and vertebrate fossil remains. The 3D textured model can also be used to create scenarios that include realistic environments in virtual, where both the public and the researchers can interact with the remains discovered during each excavation campaign. The photogrammetry was carried out using two different approaches for the campaigns 2017 and 2019. In 2017, we used a Sony Alpha 5000 camera suspended on a pole, in order to achieve a vertical image. From a heritage conservation point of view, this procedure was inconvenient because it required a person to tread on the excavation surface, thus risking to inadvertently damage some of the remains. For this reason, in 2019, we decided to perform the photography using a remotely piloted aerial system (RPAS) (Parrot Anafi). This micro aerial vehicle was small enough so that its air flow does not affect the surface of the excavation. The above-mentioned set of camera, pole and RPAS are shown in Figure 6. Figure 6. Camera Sony Alpha 5000 hanged on a pole and remotely piloted aerial system (RPAS) used in the field seasons 2017 and 2019. Figure 6. Camera Sony Alpha 5000 hanged on a pole and remotely piloted aerial system (RPAS) used in the field seasons 2017 and 2019. The camera features for the Sony camera, the Parrot Anafi on board, and the outstanding features for the RPAS are shown in Table 2. Sustainability 2020,12, 4785 8 of 19 Table 2. Features of the cameras (Sony and RPAS) used in this work. Type of Camera Camera Features Outstanding RPAS Features Sensor Focal (35 mm Equivalent F-Value Weigth Extra-Sensors RPAS Parrot Anafi 1/2.4” CMOS. 21 MP 23–69 mm f/2.4 320 g Sonar and optical sensor Camera Sony alpha 5000 APS-C (23.2 ×15.4 mm) 20.1 MP 16–50 mm f/3.5 ————– The FN3 archaeological site can be visited every day of the year because it is housed beneath a structural roof which protects it from weather conditions (Figure 7). This roof was a handicap to our work because it impeded the RPAS from picking up a clear GNSS (Global Navigation Satellite System) signal and, consequently, two problems arose: (1) the RPAS was harder to pilot and (2) it was impossible to take the pictures in automatic mode [ 43 ]. The latter problem was mitigated by means of the Extra-sensors mentioned in Table 2, but the former problem forced us to take the images manually. Sustainability 2020, 12, x FOR PEER REVIEW 8 of 20 The camera features for the Sony camera, the Parrot Anafi on board, and the outstanding features for the RPAS are shown in Table 2. The FN3 archaeological site can be visited every day of the year because it is housed beneath a structural roof which protects it from weather conditions (Figure 7). This roof was a handicap to our work because it impeded the RPAS from picking up a clear GNSS (Global Navigation Satellite System) signal and, consequently, two problems arose: (1) the RPAS was harder to pilot and (2) it was impossible to take the pictures in automatic mode [43]. The latter problem was mitigated by means of the Extra-sensors mentioned in Table 2, but the former problem forced us to take the images manually. Table 2. Features of the cameras (Sony and RPAS) used in this work. Type of Camera Camera Features Outstanding RPAS Features Sensor Focal (35 mm Equivalent F- Value Weigth Extra-Sensors RPAS Parrot Anafi 1/2.4’’ CMOS. 21 MP 23–69 mm f/2.4 320 g Sonar and optical sensor Camera Sony alpha 5000 APS-C (23.2 × 15.4 mm) 20.1 MP 16–50 mm f/3.5 -------------- The number of pictures for building the 3D model (NP) in the 2017 season was 222, the mean distance from the camera to the ground (MCG) was 2.35 m and the number of control points measured in the field (NCP) was 15; in the 2019 season the NP was 393, the MCG was 2.48 m and the NCP was 14. Figure 7. Archaeological site of Fuente Nueva 3 covered by a metallic structure (image from the scanner survey performed in 2019). The image acquisition was not performed in automatic mode for either of the 2017 and 2019 field seasons was the imaging acquisition performed in automatic mode. The images taken in 2019 were produced with the RPAS, which allows a more homogeneous picture distribution because it uses a human pilot that tries to capture them at equal distances. Contrastingly, in 2017, image acquisition was carried out with a camera assembled onto a pole. Such a procedure was constrained, however, because those parts of the site with exposed fossils could not be stepped on. To solve this constraint, some pictures were taken in an oblique position, so that the image set was not distributed in a homogeneous way (Figure 8). Figure 7. Archaeological site of Fuente Nueva 3 covered by a metallic structure (image from the scanner survey performed in 2019). The number of pictures for building the 3D model (NP) in the 2017 season was 222, the mean distance from the camera to the ground (MCG) was 2.35 m and the number of control points measured in the field (NCP) was 15; in the 2019 season the NP was 393, the MCG was 2.48 m and the NCP was 14. The image acquisition was not performed in automatic mode for either of the 2017 and 2019 field seasons was the imaging acquisition performed in automatic mode. The images taken in 2019 were produced with the RPAS, which allows a more homogeneous picture distribution because it uses a human pilot that tries to capture them at equal distances. Contrastingly, in 2017, image acquisition was carried out with a camera assembled onto a pole. Such a procedure was constrained, however, because those parts of the site with exposed fossils could not be stepped on. To solve this constraint, some pictures were taken in an oblique position, so that the image set was not distributed in a homogeneous way (Figure 8). The relative orientation of the photographs shown in Figure 8was obtained using the photogrammetric alignment process: the absolute orientation (levelling and scaling as referred to the LCS) was achieved by assigning 3D coordinates to some targets (survey control points) all over the excavation area. The survey control points have been referenced using a Total Station Leica TS03, equipped with an angular accuracy of 3” and 1.5 mm ± 2 ppm in range. The mean error after fitting the images bundle in 2017 was 4.7 mm, as shown in Figure 9. The software used in the photogrammetric process was Photoscan version 1.5.2 from the Agisoft company. Sustainability 2020,12, 4785 9 of 19 Sustainability 2020, 12, x FOR PEER REVIEW 9 of 20 Figure 8. Pictures distribution in 2017 (Sony camera and pole) and 2019 (Parrot Anafi RPAS) field campaigns at Fuente Nueva 3. The relative orientation of the photographs shown in Figure 8 was obtained using the photogrammetric alignment process: the absolute orientation (levelling and scaling as referred to the LCS) was achieved by assigning 3D coordinates to some targets (survey control points) all over the excavation area. The survey control points have been referenced using a Total Station Leica TS03, equipped with an angular accuracy of 3” and 1.5 mm ± 2 ppm in range. The mean error after fitting the images bundle in 2017 was 4.7 mm, as shown in Figure 9. The software used in the photogrammetric process was Photoscan version 1.5.2 from the Agisoft company. Figure 9. Error obtained in the photogrammetric absolute orientation of the images bundle (alignment). The 3D model was derived from the dense points cloud (Figure 9), obtained after the alignment. The point cloud was triangulated and a mesh was derived (Figure 10); in the 2017 field season, the number of points to be triangulated was 2,395,656. In order to make the most of the 3D model, a texture was projected onto the mesh, making it suitable to use as a scene to introduce in VR environments. Figure 8. Pictures distribution in 2017 (Sony camera and pole) and 2019 (Parrot Anafi RPAS) field campaigns at Fuente Nueva 3. Sustainability 2020, 12, x FOR PEER REVIEW 9 of 20 Figure 8. Pictures distribution in 2017 (Sony camera and pole) and 2019 (Parrot Anafi RPAS) field campaigns at Fuente Nueva 3. The relative orientation of the photographs shown in Figure 8 was obtained using the photogrammetric alignment process: the absolute orientation (levelling and scaling as referred to the LCS) was achieved by assigning 3D coordinates to some targets (survey control points) all over the excavation area. The survey control points have been referenced using a Total Station Leica TS03, equipped with an angular accuracy of 3” and 1.5 mm ± 2 ppm in range. The mean error after fitting the images bundle in 2017 was 4.7 mm, as shown in Figure 9. The software used in the photogrammetric process was Photoscan version 1.5.2 from the Agisoft company. Figure 9. Error obtained in the photogrammetric absolute orientation of the images bundle (alignment). The 3D model was derived from the dense points cloud (Figure 9), obtained after the alignment. The point cloud was triangulated and a mesh was derived (Figure 10); in the 2017 field season, the number of points to be triangulated was 2,395,656. In order to make the most of the 3D model, a texture was projected onto the mesh, making it suitable to use as a scene to introduce in VR environments. Figure 9. Error obtained in the photogrammetric absolute orientation of the images bundle (alignment). The 3D model was derived from the dense points cloud (Figure 9), obtained after the alignment. The point cloud was triangulated and a mesh was derived (Figure 10); in the 2017 field season, the number of points to be triangulated was 2,395,656. In order to make the most of the 3D model , a texture was projected onto the mesh, making it suitable to use as a scene to introduce in VR environments. Sustainability 2020, 12, x FOR PEER REVIEW 10 of 20 Figure 10. Mesh derived from the point dense cloud in Fuente Nueva 3. Because the 3D model to be included in the Unreal Engine should be as light as possible, we simplified the triangulated model from a lower dense cloud. Table 3 shows the dense cloud and the number of triangulated faces for the high and simplified model. Table 3. Simplified model used in Unreal Engine. High Quality Model Simplified Model (Used on Unreal Engine) Dense cloud (number of points) Number of Faces Dense cloud (number of points) Number of Faces 36,442,183 5,361,566 2,395,656 631,103 Once the 3D model is complete, we can derive a series of products such as: ortho-images from the horizontal projection, elevation sections from some particular directions, 3D volumes from regions of interest and, as mentioned above, 3D scenes to include in VR environments. We also produced an immersive VR scenario based on the FN3 site contextual data. The software supporting our VR development was Unreal Engine. We used the visual programming environment offered by Unreal Engine, especially the blueprint templates that facilitated the production tasks. To include our 3D textured model in Unreal Engine, we had to simplify the mesh so that the computer was able to perform optimally. The solution that we implemented to navigate the FN3 scenario was first person, the blueprint and the head mounted device (number 1 in Figure 11). The Oculus Rift system is suitable for room-scale concept performance (right image in Figure 11), which consists of a player that can move physically inside a room within the limitations of the sensor’s maximum range (number 3 in Figure 11). Our VR implementation was compatible with displacement just using the motion controllers (number 2 in Figure 11). When people move the head mounted device, new 3D stereo images from the scenario appear on the head mounted device displays, enhancing the player’s immersive experience. Figure 10. Mesh derived from the point dense cloud in Fuente Nueva 3. Sustainability 2020,12, 4785 16 of 19 from the point cloud. On the contrary, the use of the small drone allows to us overcome the challenge of on-site circulation, rendering more homogeneous images and spatial image distribution (right image in Figure 8). This allows to eliminate the appearance of holes in the terrain mesh. The control point error for both camera in pole (0.0047 m) and drone (0.0018 m) are very similar and a little bit better for the drone than for the camera in pole. The inclination related to the vertical direction is higher in the camera in pole (37.92 ◦ ) than using the drone (12.88 ◦ ) capture; this higher inclination may explain some small blurred textured areas in the 2017 season that does not occur in the 2019 season. Evaluating both procedures, we recommend the second method (drone-based) because it offers more advantages (heritage preservation, acquisition time, elimination of holes in the terrain mesh) than disadvantages (connection difficulties due to the presence of a metal protective structure). In addition, the image sharpness achieved by the drone camera is adequate for an accurate 3DVR. 4. Conclusions Documentation is a key function in any archaeological site, ensuring that a maximum of data can be analysed multiple times into the future. The remote sensing techniques play an important role in carrying out suitable documentation, particularly in the realistic 3D modelling of a site. The photogrammetry involved in the 3D model production guaranties an accurate positioning of the remains. The ortho-image is one of the most useful photogrammetric products, which allows for taking accurate measurements thanks to the high level of detail obtained in the imagery. From a methodological point of view, we recommend the use of small drones to acquire images in mid-sized open-air sites containing exposed and fragile elements (such as large fossil remains). At this time, the only disadvantage is the sensor size. Nevertheless, the sharpness provided by the drone sensor size camera is sufficient to guarantee an accurate reconstruction. Some partially exposed remains cannot be immediately extracted from the site and may even need to remain in situ for long periods of time, as in the case of the mammoth tusks in FN3, but our methodologies allow us to calculate some of their morphometric features, supported by the 3D model derived from the photogrammetry. Sections performed on planes of interest allow fitting curves and surfaces that inform us about the shape and size of some hidden parts of the remains. In some archaeological sites, as in FN3, there may be some geological formations or structures of interest, such as the geological fault described here. Such features can be perfectly documented using photogrammetric techniques. The 3D textured model derived from photogrammetry is suitable to include in a virtual reality scenario to reproduce the original landscape surrounding the archaeological site. The virtual reality experience achieved by the head mounted device (in our case Oculus Rift) provides four main advantages: (1) it is ideal for diffusion of contents in an attractive presentation (stereo visualization and realistic immersion feeling); (2) it is possible observe a high level of detail along the navigation experience without any damage to the remains by providing a virtual tour of the site: the public (users) can observe details that they would be unable to see in an in situ visit to the site; (3) this technology makes it possible to convert an archaeological site into portable heritage, extending the visiting capacity to vulnerable groups, specifically those with reduced mobility and/or under confinement; and (4) immersive real virtuality should acts as an incentive to increase the number of people interested in visiting the Pleistocene heritage in Orce, contributing to the economic development and local identity. Author Contributions: Conceptualization, J.F.R.-G. and J.M.J.-A.; methodology, J.F.R.-G. and C.L.-R.; software, J.F.R.-G. and C.L.-R.; formal analysis, C.A.L.-R. and J.F.R.-G.; investigation, J.F.R.-G., D.B., A.S.-R., J.A.S.-G., C.L.-G., S.T., C.L.-R., J.M.J.-A.; data curation, J.F.R.-G., D.B., A.S.-R., J.A.S.-G., C.L.-G., S.T., J.M.J.-A.; writing—original draft preparation, J.F.R.-G., D.B. and J.M.J.-A.; visualization, J.F.R.-G. and C.L.-R.; supervision, J.F.R.-G. and J.M.J.-A.; project administration, J.M.J.-A.; funding acquisition, J.M.J.-A. All authors have read and agreed to the published version of the manuscript. Funding: This research was funded by Consejer í a de Cultura, Junta de Andaluc í a, grant number BC.03.032/17 and by FEDER 2010 Operative Program Research Project number A-HUM-016-UGR18. The funder Consejer í a de Cultura, Junta de Andalucía, authorizes the publication of this results. Sustainability 2020,12, 4785 17 of 19 Acknowledgments: D.B. and S.T. are grateful for support from the Spanish government Ministerio de Ciencia, Innovaci ó n y Universidades (MICINN-FEDER) code CGL2016-80975-P, Ag è ncia de Gesti ó d’Ajuts Universitaris i de Recerca (AGAUR) code 2017 SGR 859 and CERCA Programme/Generalitat de Catalunya. S.T. is also beneficiary of the Provincia Autonoma di Bolzano (Italy). J.M.J.-A. belongs to the Research Group HUM-607, Junta de Andaluc í a. The authors would like to thank the editor of this volume and the reviewers for their useful and accurate comments, which have undoubtedly improved previous versions of this paper. Conflicts of Interest: The authors declare no conflict of interest References 1. Reilly, P. Towards a Virtual Archaeology. In Computer Applications in Archaeology; Lockyear, K., Rahtz, S., Eds.; Springer: Oxford, UK, 1990; pp. 133–139, British Archaeological Reports. 2. 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