The Digital Workflow of the Cultural Heritage Response Unit (CHRU)

1.1. Background

GIS has become a cornerstone of archaeological research and heritage management over the last decade. GIS software allows archaeologists to store, analyse, and visualize spatial data with great efficiency. Common applications include mapping excavation units and artifacts, modelling past landscapes, and performing spatial analyses such as viewshed or density analysis. Recent literature shows that nearly half of published GIS-based studies in archaeology focus on spatial analytic approaches (e.g. distribution, pattern and network analyses), and about one-third on heritage management uses like site inventories (e.g. McCoy & Ladefoged 2009, Menéndez-Marsh et al. 2023, Iacono & Fritsch 2023).

One of the most advanced techniques in archaeological studies in the past decades has come from remote sensing technologies, especially airborne LiDAR (Light Detection and Ranging) and high-resolution satellite imagery. These tools allow archaeologists to detect and document sites without excavation, covering large areas that would be impractical to survey on foot. Satellite imaging has also matured as an archaeological tool in the past decade. Very high-resolution satellite images (with resolution under 1 m per pixel) became more accessible, and analysts increasingly applied techniques like multi-spectral analysis and machine learning to identify archaeological signatures from space (e.g. Kadhim & Abed 2023, Argyrou & Agapiou 2022, Lambers et al., 2019). Several projects have adapted remote assessment of the situation of cultural heritage sites in terms of damages and risks using satellite data and GIS methods (e.g. Tapete & Cigna 2018, Masini & Lasaponara 2020, Rayne et al., 2023, Marzban et al., 2024).

Three-dimensional modelling in archaeology has grown over the past decade, driven in large part by advances in photogrammetry and laser scanning. Image-based 3D reconstruction – especially Structure from Motion (SfM) – has become practically standard in archaeological fieldwork for recording excavation units, artifacts, and architecture in fine scale detail. In recent years, the availability of high-quality digital cameras, UAVs, and user-friendly software (often low-cost or open-source) together improved 3D documentation of archaeological objects. Researchers now can generate millions of 3D points (point clouds) and textured models simply by taking a series of photographs in the field and processing them with SfM algorithms (e.g. Anderson 2020).

In the field of on-site documentation, many projects have strived for “paperless” workflows. This means using digital tools, such as tablets, GPS/GIS units and mobile databases to record excavation metadata, stratigraphic information, and survey observations in real time. Despite their benefits, digital tools present challenges. Data management issues, including storage costs and format obsolescence, threaten long-term accessibility (e.g. Richards et al., 2013). The FAIR principles (Findable, Accessible, Interoperable, Reusable) are increasingly adopted to mitigate these risks (e.g. Wilkinson et al., 2016).

Here in this study, we show how we integrated each of these technologies in the workflow of our project. We present examples from remote assessment of the situation in the crisis area and affected sites, management of different sources of datasets and documentation of sites and objects on the ground.

1.2. General Introduction and the Workflow of the CHRU

To facilitate the establishment of an international operational response mechanism for the rapid protection of cultural heritage in crisis situations, the German project KulturGutRetter has developed the Cultural Heritage Response Unit (CHRU) since 2021. The CHRU consists of a cross-sectoral team integrating expertise from both civil protection and cultural heritage preservation. For this purpose, the German Federal Agency for Technical Relief (THW), the German Archaeological Institute (DAI) and the Leibniz Centre for Archaeology (LEIZA) combined their specialized knowledge and experience to establish Minimal Standard Procedures (MSP) and Standard Operating Procedures (SOP) to ensure a well-coordinated process during deployment. The CHRU consists of several units, such as an IT unit, a movable cultural assets (MCA) unit and an immovable cultural assets (ICA) unit, in which cultural heritage experts are joined by experts for civil protection. Other essential team functions such as the Team Leader, the Structural Engineer, the Liaison Officer, the Logistics Officer, the Water Purification Expert etc. managed by THW, ensure the operational effectiveness of the CHRU (e.g. Domenech de Cellès & Rehberger, 2025). The activation of the CHRU (Figure 1) can be triggered by a request for assistance from the affected state, submitted via the UCPM (European Civil Protection Mechanism), the UN OCHA (United Nations Office for the Coordination of Humanitarian Affairs), or alternatively through a bilateral request directly to the German Federal Foreign Office. When cultural heritage is impacted by a disaster anywhere in the world and the UCPM is activated, Germany offers assistance of the CHRU via the UCPM. Thereafter, the EU coordinates the contribution plans of the participating states, and once the affected country accepts the offer, the CHRU is deployed to the affected area. The deployment happens following completion of the initial search and rescue phase (72 h) after a disaster. The LEMA (Local Emergency Management Authority) coordinates all support units and international actors in the affected country. The CHRU Liaison Officer and Cultural Heritage Advisor communicate and coordinate all relevant information with the LEMA and local cultural heritage authorities. Shortly after activation, the CHRU’s digital units begin their tasks and coordinate their responsibilities even before deployment.

Figure 1

The digital infrastructure itself can be organised into three main components. First, remote sensing and GIS is part of the remote sensing and monitoring unit at the IT department at DAI. In principle, this unit can operate under any circumstances since its tasks are related to remote assessment of the situation as far as data availability allows. We show the workflow of this unit in Figure 3. Second, data management is also part of the IT department, and provides support regarding the hardware and software parts of the project including a DBMS (Database Management System). The third unit is the field documentation crew which consists of two sub-units, one for movable objects, which is known as MCA (Movable Cultural Assets) and is coordinated by LEIZA, and another for immovable objects, known as ICA (Immovable Cultural Assets) and managed by the architecture department at DAI. A detailed description of each component and their tasks are presented in the next sections.

The main digital infrastructure of CHRU (Figure 2) consists of a diverse set of data, tools and methods. However, the overall process can be classified step by step: 1. Mission Initiation, 2. Remote sensing and GIS maps, 3. QGIS to QField project conversion, 4. Initial Field Reconnaissance and Data Acquisition, 5. Data Synchronization, 6. Expert Precise Data Refinement, 7. Continuous Data Integration and Consolidation, 8. Final Data Handover and Archiving. These different steps are done by the different units specified in Figure 2 and involve cooperation between them from one step to the next.

Figure 2

2.1. Remote sensing and GIS

In the case of an activation, we start with gathering the most recent datasets from various remote sensing and GIS sources, including freely available satellites as well as commercial ones. After acquiring and analysing all the available data and information on the affected area, and more precisely the affected cultural heritage, we generate data packages and maps which are handed over to the data management and the field crew.

Satellite imagery is available from several key sources, including the European Space Agency (ESA), the United States Geological Survey (USGS), and the National Aeronautics and Space Administration (NASA), all of which provide datasets free of charge under open access policies. These satellite platforms offer imagery with varying spatial, spectral, and temporal resolutions. Notable examples include Sentinel-1, Sentinel-2, and Landsat-8 and 9. While these datasets are valuable for obtaining a general overview of environmental impacts, their spatial resolution – at best 10 to 15 m – limits their ability to capture fine-scale details. In contrast, commercial satellites can achieve spatial resolutions as high as 30 cm, thereby addressing this limitation, though often at a significant financial cost. However, sometimes commercial VHR (very high-resolution) imagery can be obtained at a reduced or no cost by some companies under academic or education programs. Consequently, it is essential to consider an integrated approach that leverages both freely available datasets and very high-resolution commercial imagery. In our case, the SKD (Satellite Based Crisis and Situation Service) from BKG (Federal Agency for Cartography and Geodesy) provides us with VHR data free of charge on demand. Such a strategy can provide a cost-effective foundation for remote sensing applications, particularly in the field of cultural heritage.

The remote sensing and monitoring unit of CHRU has various approaches for different case studies generally identified as rapid response, preventive measure and long-term monitoring (Marzban et al., 2024). However, in case of an emergency, the initial course of action involves reviewing the activation list of the Copernicus Emergency Management Service (CEMS) to assess whether relevant analytical products are already available for the area of interest. If no such products exist, we initiate independent data acquisition and procurement processes. Given the dynamic nature of such situations, methodological flexibility is crucial. The selection of data processing and analysis approaches is ultimately determined by the availability of pre- and especially post-event data and the operational resources at hand, ensuring an adaptive and context-sensitive response to the detection of potentially affected sites.

In the event of a CHRU deployment, Copernicus data can be rapidly integrated into a QGIS project. Within this environment, the “KGR Finder” tool (Fritsch et al., 2024) can be utilized to assess whether any regions of interest within the affected areas contain cultural heritage sites. Additionally, the predefined CEMS impact zones can be queried individually using the layer selection tool, enabling targeted analysis and decision-making. Furthermore, for detail situation assessment of the affected sites we either order or task for VHR satellite data through our partner institutes and commercial subscriptions.

The overall goals of the remote sensing and GIS unit of the CHRU is to provide heat maps and identify affected sites. Furthermore, focused maps of affected cultural heritage sites together with GIS plans of the sites are produced for further structural assessment of damages remotely (Figure 3). The final products are organised within a QGIS project for mission planning decisions that are relevant for the ICA and MCA units.

Figure 3

2.2. Data Management

The aim is to establish the necessary conditions for integrating all domains involved in data collection during disaster response, as well as managing the associated data flows efficiently. To achieve this, appropriate software and hardware is available and adapted to support data collection at the required level of detail while facilitating seamless data exchange. Emphasis is made on enabling the team on the ground with rapid, straightforward on-site data acquisition possibilities, including the capability for fully offline operation when necessary. Additionally, the varying requirements and methodologies for the digital documentation of both movable and immovable cultural assets must be carefully considered and accommodated.

The initial step for the mission crew to prepare from a digital point of view is the preparation of mobile devices. This involves uploading information and analysed remote sensing and GIS datasets into the tablets together with the CHRU standard data model. For this we use “QFieldCloud” and the QGIS plugin “QFieldSync” in order to transfer the data model into a readable project format for the QField app on the tablets.

The CHRU data model provides the foundation for the structure, hierarchy, and field naming used in mobile applications for field documentation, such as iDAI.field mobile and QField. It is designed to meet a range of specific requirements, which arise both from the varying professional needs of the different disciplines involved in the CHRU mechanism – such as building researchers, archaeologists, architects and conservation experts – and from the practical challenges of working in emergency situations.

Using a GIS application that is generally intended for fieldwork in a single dimension (layer) to map data in a CHRU deployment across several floors presents a challenge regarding the project architecture. All aspects of an operation, such as mapping hazards, damages, and movable cultural assets must function across multiple vertically stacked floors. Furthermore, a separate map is required for each floor that displays all recorded data individually without visual overlap. The current solution provides separate mapping layers for each floor. This allows mapping and viewing data layers floor by floor through the map theme tool. However, this data management approach affects the performance of QField. To regulate data traffic, the number of layers is kept to a minimum. Another workaround to minimize data processing is to split the QField projects by floor. Nevertheless, the data is still stored in a shared database. This approach has been tested and performed well during our practical test missions. However, we always try to improve the efficiency of our approaches if possible and update them with recent technological improvements.

Another challenge is that emergency deployments by the CHRU happen only on a short notice time – typically 72 hours – leaving little room for preparation or adaptation on site. Volunteer teams may lack technical expertise, and local conditions such as infrastructure or environment (urban vs. rural) are often unknown until arrival. Therefore, all technical requirements, including hardware, software, and data structures, must be fully prepared in advance. Mobile applications must come preconfigured with all necessary fields and categories, supported by our data model that balances usability, detail and flexibility. This model must meet the diverse needs of various disciplines while remaining practical for use on mobile devices, ensuring efficient data collection and smooth synchronization without conflicts.

2.3. Field documentation

Depending on the type of operation, we employ different methods and follow standard workflows. In the case of immovable cultural heritage, such as archaeological sites, museums, buildings, citadels, castles, etc., if possible, we conduct UAV surveys to have a 3D overview of the site and the damages that are visible from outside. If it is possible to investigate and map the inside of a structure, we use laser scanners. Furthermore, an accurate geolocation of the structure, as well as a detailed damage and condition assessment, including the evaluation of all further stabilization measures to be taken, are imperative and among the first phases of the documentation procedure. Accurate location naming is particularly important, as it serves as a spatial reference for associated movable heritage.

In the case of movable heritage, like statues, ceramics and archival material, the app supports more complex workflows, including the documentation of interventions carried out in a lightweight modular lab developed by LEIZA (including photographic documentation, dry- and wet-cleaning, packing and transport). Objects pass through multiple stages, handled by different experts, and their status is continuously updated as they move through the process. QR codes and a local network infrastructure are used to facilitate object tracking and ensure seamless data flow between workstations. Textual data is entered via predefined forms developed by each expert unit, which adhere to standardized requirements but remain adaptable. When necessary, additional fields can be added during the operation by modifying the central QGIS project and distributing the update to mobile devices. To complement written entries, the system also supports the inclusion of audio and video files when textual input is impractical or insufficient.

The use of mobile devices for field documentation must meet specific hardware and software requirements. Devices must be robust, portable, and capable of handling substantial data volumes efficiently to support consistent and reliable use in challenging conditions. Corresponding software must facilitate intuitive data entry and ensure seamless synchronization and integration of collected information. Within this framework, QField plays a central role, with each project area leveraging its functionalities according to specific needs. A common identification system links all datasets, primarily through geospatial data and a parallel system based on UUIDs (Universally Unique Identifiers) and QR codes. A key innovation is the introduction of a standardized, credit card-sized label (Figure 7). It is designed for use with movable cultural assets, serving as targets for survey and crack-width measurements, and includes a scale, a colour reference, as well as both printed and scannable UUIDs. The ID card allows immediate linkage between a physical item and its digital record in QField. Cultural heritage assets that were originally immovable but have to be recovered and become movable are subsequently labelled in the same tagging system. This approach ensures consistent identification, traceability, and retrievability of all data.

Within the CHRU framework, the QField app primarily serves to document cultural heritage in its state following a disaster event and to record any emergency measurements undertaken by the CHRU on the building itself or the associated movable heritage. This task is carried out by experts from diverse disciplinary backgrounds, such as archaeology, architecture, restoration and conservation, each employing distinct terminologies and methodologies. While these differences must be partially harmonized through a consolidated QField data model, the app also allows experts to work within discipline-specific forms and tabs, enabling parallel workflows with synchronized data exchange. The use of dropdown menus and radio buttons improves consistency in data entry, reducing the risk of errors and enhancing efficiency.