Technological advances in Virtual Reality (VR) in recent years have the potential to have an ever-increasing impact on our everyday lives. VR makes it possible to explore a digital world in an immersive experience through a Head Mounted Display (HMD). Combined with tools for 3D documentation, modelling and software for creating interactive virtual worlds, VR has the potential to play an important role in the preservation and visualisation of cultural heritage for museums, educational institutions and other cultural sectors. It opens up a new form of scientific communication that can benefit historical and cultural heritage objects that are either damaged, destroyed or too far away from an interested visitor. This article presents a review of three virtual reality projects carried out in collaboration between BİMTAŞ, a company affiliated with the Greater Municipality of Istanbul, Turkey, and the Photogrammetry & Laser Scanning Laboratory of the HafenCity University Hamburg, Germany. The objective of this collaborative endeavour was to exemplify an immersive and interactive visualisation of three historical Turkish monuments (Selimiye Mosque in Edirne, the Rumeli Hisarı fortress in Istanbul, and the Istanbul Çatalca İnceğiz Caves) using the recently developed virtual reality system, HTC Vive. The objective of the projects was to create a virtual reality (VR) representation of the monuments, allowing users to interactively explore them from a first-person perspective.

The potential of unmanned aerial vehicle (UAV) or unmanned aerial systems (UAS) photogrammetry for use in cadastral surveying tasks was explored as part of a research collaboration with the HafenCity University Hamburg and the Schleswig-Holstein State Office for Surveying and Geoinformation in Elmshorn, Germany. The building ensemble of a farm in Tensbüttel-Röst near Albersdorf, Germany was recorded with the DJI Phantom 4 Pro KlauPPK UAV system in various aerial flight configurations. The objective was to investigate and analyse the achievable geometric accuracy for a photogrammetric cadastral survey. The accuracy of the aerial triangulation was evaluated through the utilisation of diverse ground control point and check point configurations with the Agisoft Metashape software. The coordinates of the building were determined through the three different point measurement techniques. The roofscapes of the buildings and the 3D buildings were modelled as additional products. A digital orthophoto was also generated with the corresponding ground resolution. The accuracy, completeness and cost-effectiveness of the results of the UAV/UAS photogrammetry are discussed in comparison to the classical tachymetric building survey. It could be demonstrated that photogrammetric cadastral surveying is technically and economically feasible for building ensembles. However, the legal framework for this is not yet in place in some German federal states.

The use of Virtual Reality (VR) is becoming increasingly important and popular. This technology is widely used in various fields such as industry, construction, architecture, medicine and scientific research. With the rapid development of VR technology, the cost of the required hardware is decreasing, making this technology available to a wider range of users. VR applications offer many opportunities to present different topics in a novel and informative way. This paper presents the development of a VR application for the "Villa Michaelsen" (hosting the Falkenstein Doll Museum) in Hamburg, Germany for the 100 years anniversary. It offers the possibility to move in and around the architectural historic building, designed and built 1923 by the architect Karl Schneider, a representative of the New Building Movement, and to look at different information, photos as well as construction phases and drafts.

The study of historical maps has gained significant importance in recent years due to their ability to shed light on past geographical and topographic landscapes since they serve as crucial sources for understanding past conditions. They not only provide insights into the geography and topography during the time they were created but also allow for studying long-term changes over time. In this study, an oversized historical map of the Bailiwick of Neuland from the years 1780 to 1790 was discovered in the archives of the municipal building office in Winsen an der Luhe, Germany. The map, measuring approximately 5 m × 2 m, was digitised by photogrammetric methods and subsequently georeferenced. The process involved photographing the map with two different cameras and two UAV systems at the Geodetic Laboratory of HafenCity University Hamburg. This allowed to generate a high-resolution orthophoto from each data set. The resulting orthophoto achieved a pixel size of 0.2 mm, ensuring a detailed representation of the map. To ensure accuracy, the best photo block was scaled in a bundle block adjustment using ground control points with an accuracy of 1 mm and scale bars with an accuracy of 0.1 mm. Georeferencing of the historical map was conducted using current digital orthophotos of Lower Saxony with a resolution of 20 cm. A third-degree polynomial transformation was applied during georeferencing, resulting in mean residuals of 2.5 m at the ground control points. This process ensured that the historical map was accurately aligned with the current digital orthophotos, allowing for precise spatial referencing.

The sensors in modern mobile phones (running either the Android or iOS operating system) have become increasingly sophisticated, to the extent that they can be used as measuring systems for a wide range of applications. On the one hand, GNSS (Global Navigation Satellite Systems) and IMU (Inertial Measurement Unit) provide precise positioning of smartphone sensors. On the other hand, the inbuilt cameras offer an increasingly high geometric image resolution. In order to investigate the potential of mobile phones for creating 3D models of small objects for the documentation of museum artefacts, the Laboratory for Photogrammetry & Laser Scanning of the HafenCity University Hamburg tested various smartphones for geometric accuracy under laboratory conditions. Four Galaxy S-series smartphones of Samsung (S21+, S22, S23, S24 Ultra) and two Apple iPhones (13 Pro and 15 Pro Max) were used for the tests. The image data sets of three distinct test objects, captured with disparate mobile devices, were processed in Agisoft Metashape into 3D models by triangle meshing and subsequently compared with highly accurate reference data from an ATOS 5 structure-light projection system. Some selected examples of image data sets recorded with the iPhone 15 Pro Max were also processed in the Polycam app. The results of the geometric accuracy analyses demonstrated that the image data captured by smartphone cameras could be processed into highly accurate three-dimensional models of the objects. The deviations from the reference data were only marginally inferior to those observed in the models generated from image data obtained from a SLR camera.

The little-known Roman gold mining site "Gralheira" is located near the well-explored mine of Tresminas. The 2.5 km long, almost dead straight archaeological monument from the first and second centuries AD is currently under threat from possible mining activities on the one hand and from modern waste disposal in the pits on the other. Since 2019, the Roman mining traces have been investigated by means of intensive field inspections, terrestrial 3d laser scanning and aerial photography. The following article will present first impressions and findings on this structure, as well as questions and preliminary interpretations.

This article summarizes the Special Issue of Cartography and Geomedia. Here, Cartography and Geomedia presents a view of cartography as a combination of technology, science, and art, with a focus on the development of geomedia in a geomatic and design-based context. Individual considerations are presented according to the following topics: efficiency of mapping techniques; historical cartographic works in a geomedial context; cartographic pragmatics for cultural heritage, teaching, and tourism; and pragmatism in gaming cartography. The main conclusion is that the two approaches to learning, revealing, and understanding geographic phenomena-starting from a specific geographical phenomenon and starting from maps and geomedia to understand geographical space-have their pragmatic strengths.

This paper summarizes recent research into current terrestrial laser scanners undertaken by the HafenCity University Hamburg and gives an assessment of the geodetic accuracy of the latest generation of scanners. Three separate independent test methods are presented to investigate the geometric accuracy of terrestrial laser scanners under laboratory conditions: (a) distance measurement accuracy to b/w targets and spheres on the 20-m comparator track, (b) comparison of spatial distances in the 3D test field on b/w targets, and (c) investigation of the flatness deviation following the guideline VDI/VDE 2634 (VDI/VDE 2012) on a flat stone slab. The following laser scanners were tested in the lab: Leica BLK360 (2017), Leica RTC360 (2019), Z+F IMAGER 5016 (2019, 2020), Z+F IMAGER 5010 (2020), and Faro Focus 3D X330 (2020). The reference measurements were realised with the Leica Absolute Tracker AT960 (2017, 2020) and with the Leica TS60 total station (2019). The results of the geometric accuracy tests in the laboratory show very small deviations in the range of 1–2 mm for most of the scanners, thus corresponding to the manufacturer’s specifications. In addition, five laser scanners were tested in accordance with instruction sheet 7-2014 of the German Society for Geodesy, Geoinformation and Land Management (DVW) for standardised testing of terrestrial laser scanners in the outdoor area of HafenCity University Hamburg. For the execution of the field test procedure, only the standard equipment and software of the respective manufacturers were used. The entire field test procedure, including data acquisition and evaluation, was completed within 4 to 5 h for each scanner. As expected, no significant distance or angle deviations were detected in any of the measurement systems, so that the tested laser scanners are ready-to-use, taking into account the measurement volume recorded.

The development of increasingly powerful Unmanned Aerial Vehicles (UAV) is progressing continuously, so that these systems equipped with high-resolution sensors can be used for a variety of different applications. With the Matrice 300 RTK, Da-Jiang Innovations Science and Technology Co. Ltd (DJI) has launched a system that can use the high-resolution camera Zenmuse P1 or the laser scanner Zenmuse L1 as a recording sensor, among other sensors. In order to investigate the geometric quality of these two sensors, HafenCity University Hamburg, in cooperation with LGV Hamburg, NLWKN in Norden and the German Archaeological Institute in Bonn, flew over the 3D test field in the Inselpark in Hamburg-Wilhelmsburg on 5 August 2021 with the P1 camera and the L1 laser scanner. Using the Matrice 300 RTK as carrier platform, the test field was recorded in various configurations at altitudes between 50 m and 90 m above ground. Prior to the UAV flight campaign, 44 marked ground control points (GCP) were signalised in the test field, which had already been surveyed by LGV in 2020 using geodetic measurement methods to achieve a coordinate accuracy of ±5 mm for each GCP. The results of aerial triangulations as well as 3D point clouds generated from image data and laser scanning are compared with reference data in order to demonstrate the accuracy potential of these measurement systems in this paper.

A correction to this paper has been published: https://doi.org/10.1007/s41064-021-00143-2

Technological advancements in the area of Virtual Reality (VR) in the past years have the potential to fundamentally impact our everyday lives. VR makes it possible to explore a digital world with a Head-Mounted Display (HMD) in an immersive, embodied way. In combination with current tools for 3D documentation, modelling and software for creating interactive virtual worlds, VR has the means to play an important role in the conservation and visualisation of cultural heritage (CH) for museums, educational institutions and other cultural areas. Corresponding game engines offer tools for interactive 3D visualisation of CH objects, which makes a new form of knowledge transfer possible with the direct participation of users in the virtual world. However, to ensure smooth and optimal real-time visualisation of the data in the HMD, VR applications should run at 90 frames per second. This frame rate is dependent on several criteria including the amount of data or number of dynamic objects. In this contribution, the performance of a VR application has been investigated using different digital 3D models of the fortress Al Zubarah in Qatar with various resolutions. We demonstrate the influence on real-time performance by the amount of data and the hardware equipment and that developers of VR applications should find a compromise between the amount of data and the available computer hardware, to guarantee a smooth real-time visualisation with approx. 90 fps (frames per second). Therefore, CAD models offer a better performance for real-time VR visualisation than meshed models due to the significant reduced data volume.

In recent years, the potentials of virtual and augmented reality (VR/AR) have attracted a growing interdisciplinary community of international researchers and users. Numerous projects exist in research fields, such as cultural heritage and architecture, urban and regional planning, construction planning and product development, training simulations (e.g., rescue services) and education. While AR is commonly understood as an extension of observable reality through the combination of reality and virtuality, VR is associated with the visualization and simultaneous real-time perception of reality and its physical characteristics within interactive virtual environments. In the VR and AR community, the year 2015 is often associated with the free release of the Unreal Engine, a formerly proprietary game engine used in the computer gaming industry. The free availability of established game engines has given a powerful impulse to modern visualization disciplines. As game engines are bound to an understanding of ‘world-building’, the reference to geographic space (concerning virtual representations of real physical or fictional environments) is inherent. Therefore, it is not surprising that there is a vivid and steadily ongoing international research debate on how to use the potentials of virtual environments and augmented spaces for a user-oriented cartography and spatial visualization. Moreover, these virtual or augmented spatial media can serve as ‘virtual labs’ which are used for empirical research with standardized procedures and for visual analytics. The possibilities of game engines further benefit from the availability and compatibility of mass media hardware systems, such as head-mounted displays (HMDs) or smartphones. These technical devices strengthen the feeling of immersion into these solely virtual or virtually extended environments, which leads to new capabilities of experiencing a realistic 3D environment from an ego-perspective in a simulated 1/1 scale. The demand for a high realism also bears potentials for the integration and transformation of traditional and new geospatial data resources, such as remotely sensed data, 3D city models as well as thematic assets created by professionals or ‘home brewers’. This special issue is a collection of current research projects showing the potentials of AR and VR, with a specific focus on the visualization of spatial information. It is part of the work of the DGfK/DGPF joint commission on “Virtual and Augmented Reality” (founded in 2019): Ian Lochhead and Nick Hedley (Burnaby, BC, Canada) developed a prototype of an immersive virtual GIScience data visualization space called “IVEVA”. In their article, they present a collection of 3D data-driven geovisualization case studies based on the IVEVA VR interface. Their examples and results show the potentials of VR interfaces for immersive visual analytics. Thomas P. Kersten, Daniel Drenkhan and Simon Deggim (Hamburg) address the topic of performance for smooth real-time VR visualization. Using a case example in the field of cultural heritage, the Fortress Al Zubarah in Qatar, they conduct and discuss a performance analysis of real-time visualization in VR. Claudia Lindner, Annette Ortwein, Kilian Staar and Andreas Rienow (Bochum) provide insights on how VR and AR techniques serve to visualize extra-terrestrial data. These VR and AR applications are developed for educational purposes and deal with case examples on Mars. Tymoteusz Horbiński and Krzysztof Zagata (Poznań, Poland) address the meaning of cartographic symbols used in the Video Valheim. The set of symbols used in this game adapt the historical context of the Viking era. Using an online survey, the authors empirically investigate interpretations of the cartographic symbols. * Dennis Edler Dennis.Edler@ruhr-uni-bochum.de

The Ocean Floor Observation and Bathymetry System (OFOBS) is an underwater survey platform, which is designed and developed for research in the Polar Regions by the Alfred Wegener Institute (AWI). The tailored deep tow system brought a new perspective and clarity from Arctic Ocean by its optical and acoustic sensors. During the PS101 expedition at the Karasik seamount, OFOBS provides a novel picture of megafauna’s habitats. In this study, we develop a methodology to convert the imagery dataset to micro-bathymetry in order to provide primary data for object detection and habitat mapping which will provide a better understanding of arctic benthic habitats. The methodology is based on the underwater photogrammetry workflow and two different point cloud classification methods adopted for sponge detection in 3D point clouds, to facilitate habitat mapping with a focus on the central of Karasik seamount where an extensive and dense assemblage of the Geodia sponges is dominating the seafloor.

Virtual Reality (VR) has established itself in recent years in the geosciences through its application in the immersive visualization of spatial data. In particular, VR offers new possibilities for the user to acquire knowledge through playful interaction within a virtual environment. This paper details the development and implementation of a new form of knowledge transfer, based on interactivity within a VR system. The particular use-case discussed is a VR application focusing on the four-masted barque Peking. From 2023 on, the restored ship will form an important exhibit in the future German Hafenmuseum in Hamburg. The new VR application offers users the possibility to enter and explore a virtual model of the Peking and find out more information at three separate points of interaction (3D object models, sails and ship flags). These interaction points provide a timely opportunity to examine several of the theoretical aspects of knowledge transfer through interactivity and integrate them in the development of the VR application. Above all, the VR application should be an important part of the learning process for the user. There remains still much potential for further research into more advanced approaches such as support for user-input questions and tailored content.

As virtual reality (VR) and the corresponding 3D documentation and modelling technologies evolve into increasingly powerful and established tools for numerous applications in architecture, monument preservation, conservation/restoration and the presentation of cultural heritage, new methods for creating information-rich interactive 3D environments are increasingly in demand. In this article, we describe the development of an immersive virtual reality application for the Imperial Cathedral in Königslutter, in which 360° panoramic photographs were integrated within the virtual environment as a novel and complementary form of visualization. The Imperial Cathedral (Kaiserdom) of Königslutter is one of the most important examples of Romanesque architecture north of the Alps. The Cathedral had previously been subjected to laser-scanning and recording with 360° panoramic photography by the Photogrammetry & Laser Scanning lab of HafenCity University Hamburg in 2010. With the recent rapid development of consumer VR technology, it was subsequently decided to investigate how these two data sources could be combined within an immersive VR application for tourism and for architectural heritage preservation. A specialised technical workflow was developed to build the virtual environment in Unreal Engine 4 (UE4) and integrate the panorama photographs so as to ensure the seamless integration of these two datasets. A simple mechanic was developed using the native UE4 node-based programming language to switch between these two modes of visualisation.

Cultural landscapes are those that are shaped through the combined forces of cultural and natural activity, typically over a long period that may reach back to historic and prehistoric times. Amongst these, the documenting, modelling and visualisation of cave landscapes have always been particularly important for scientific communities such as speleology. In the current state of the art, terrestrial laser scanning provides a level of documentation of objects whose accuracy cannot be achieved by conventional methods. In addition to the highly accurate metric and geometric information, visual information brings incredible richness to the presentation of data. Virtual reality (VR) allows individuals to immerse themselves within virtual environments to explore monuments and other cultural heritage sites up close. More and more, VR systems are available at lower prices and are not only limited to VR labs. In this paper, we present research on the generation of a virtual 3D model of the İnceğiz caves, located at the Çatalca district of Istanbul, Turkey, and its integration within the Unity 3D game engine. This project, carried out as a collaboration between BİMTAŞ, a company of the Greater Municipality of Istanbul, Turkey and the Photogrammetry & Laser Scanning Lab of the HafenCity University Hamburg, Germany, aimed at developing an immersive and interactive VR visualisation of the cave for the HTC Vive Pro VR system. The entire workflow, from data acquisition to VR visualisation, is described here in detail with particular emphasis given to the 3D modelling of the cave and its integration within a VR environment.

“A picture is worth a thousand words”: a famous quote about knowledge dissemination but also literally true. The documentation of cultural heritage (CH) monuments is carried out by measurements and photos and stored in 3d models – not by textual information alone. So what could be a more straightforward way to inform the public about CH than visual information? This approach can be extended not only by providing static images or videos from predefined angles but by giving the user the opportunity to interactively explore the virtual representation and interact with the scene. Recent advances in contemporary Virtual Reality (VR) have made it available to more people as prices have dropped. New devices have entered the market so that VR is not limited to VR labs, but is available even at home. With modern head-mounted displays the user can immerse himself in the virtual CH monument to explore and interact with it. Game engines offer tools for rapid development of interactions and help to produce visually appealing worlds.In this paper is presented the generation of a virtual 3D model of Rumeli Hisarı, an Ottoman fortress at the Bosporus in Istanbul, Turkey (Fig. 1) and its processing for data integration into the game engine Unity. The project has been carried out as a co-operation between BİMTAŞ, a company of the Greater Municipality of Istanbul, Turkey and the Photogrammetry & Laser Scanning Lab of the HafenCity University Hamburg, Germany with the aim of a VR application for an immersive and interactive visualisation of the fortress using the VR system HTC Vive. The workflow from data acquisition to VR visualisation, including the necessary programming for navigation, is described. Furthermore, the possible use (including simultaneous multiple users environments) of such a VR visualisation for a CH monument is discussed.