Image analysis for heritage mapping, using open-access software and remote sensing data
This is a ‘how to recruit, manage and support volunteers’ guide produced as part of the Digital Skills for Heritage’s Digital Volunteering programme.
1. Project background
Hidden within today’s farmland and woodland are subtle earthwork remains of archaeological sites – from prehistoric burial mounds, enclosed settlements and huts, to Roman camps, farms and roads, and medieval hamlets, villages, fields and mines. Many are recognised and recorded on the Historic Environment Record (HER), but new technology allows us to discover and map previously unknown examples. This hidden heritage is important to discover and promote as it tells us more about the evolution of the countryside and its heritage value.
Unlocking Landscapes was designed and delivered by staff of the Department of Archaeology and History at the University of Exeter. The Department of Archaeology and History hosts staff whose research interest combines digital, remote archaeological prospection, the archaeology of South West Britain, and public engagement through ‘community archaeology’ projects.
Unlocking Landscapes focused on the previously unrecorded heritage – archaeological sites and landscapes – in Devon and Cornwall.
2. Recruitment
The project did not set out with a predetermined idea of the types of digital volunteers that it would target, but it aspired to provide inclusive opportunities for people with restrictions of geography, physical and mental health, and work/care commitments. It engaged a wide array of individuals with these attributes, with and without existing digital skills, and experience of archaeology and heritage.
Whilst the age range of digital volunteers was mixed, it notably lacked those under 40 years of age, and mostly included those aged 50 to 70 years. Some volunteers worked, but the majority were retired. Nearly all volunteers were based in the counties of Devon and Cornwall, though a small number who were based elsewhere in the UK or overseas had links with the region.
Volunteers were recruited from a register of interest for volunteering (derived from emails received during 2020 and 2021, during pandemic lockdowns), advertising via an existing project’s Facebook page (Understanding Landscapes) and sharing by its followers, and via expressions of interest following the initial press release. Promotion and sharing via Facebook was the most successful means of recruitment.
LiDAR is an active remote sensing technology that through laser pulses allows us to ‘see through vegetation’ and generate high-resolution Digital Elevation Models (DEM). Courses in the use of LiDAR data for archaeological mapping provided for the Devon Partnership NHS Trust’s ‘Devon Recovery Learning Community’ were co-delivered with a DRLC tutor.
3. Volunteer support
Initial online training workshops were provided to equip volunteers with the necessary digital skills to undertake the work, and to build confidence. Monthly drop-in Zoom meetings were organised to support the needs of volunteers in the first six months of the project, run in daytime and evening. As the confidence and ability of volunteers grew, these were reduced to ad hoc times when needed. Email support was used frequently by all volunteers. In order to facilitate peer support within the group, a private Facebook group was created and this proved a useful medium for ‘out of hours’ support.
4. Digital technology and tools
Digital volunteers:
- were supplied with LiDAR data using Dropbox Professional.
- explored LiDAR data and mapped discoveries using Google Earth Pro.
- communicated with the project team through Teams, Zoom, Facebook, and by email.
Costs
- Dropbox Professional – £199 per annum
- Google Earth Pro – free
- Teams, Zoom, Facebook, email – free
5. Project Stages
1. Define scope of project in collaboration with stakeholders – Local Authority archaeologists, AONB and National Parks heritage representatives to achieve academic and non-academic goals.
2. Procure and process LiDAR data – making sure that you create appropriate visualisations for manageable-sized area, in an appropriate format (.kmz for Google Earth Pro).
3. Digital volunteer recruitment and training – recruit and train in staged cohorts if large numbers of volunteers are intended.
4. Digital volunteer management – ongoing support of volunteers, to include periodic refreshers on task, skills and desired outcomes.
5. Creation of datasets – work to verify volunteer discoveries, map and catalogue these in a format agreeable to the recipient Historic Environment Record.
6. Signposting – make volunteers aware of what happens when the project ends, including opportunities for further volunteering with your or other organisations.
6. Key learnings
Define your area of interest
It is important to set realistic geographic extents for your project, based on the availability of staff time and the number of volunteers. Your coverage will also be shaped by your approach – determine what kinds of archaeological sites you will prioritise mapping of.
Decide your parameters for recording
What is it that you will record. Will you record every earthwork anomaly, even if mundane (eg early modern quarry or removed field boundary)? Will you be selective in what you record (ie monument types or likely age) in order to achieve wider coverage and make a particular contribution to understanding of a particular period in time?
Develop your project in collaboration
It is important to realise that, whilst the discovery and recording of large numbers of new archaeological sites is both exciting and interesting, it requires work to include these in the Historic Environment Record. Work with your local HER to agree a format for reporting that eases workload for them.
Assess the interests of each volunteer
Use particular interests to define the scope of work asked of each person (eg geographic area, period of history, type of site or landscape) to maintain enthusiasm (if needed, some volunteers will be happy follow a generic methodology).
7. Key challenges
Computing problems
Make IT requirements clear from the start in order to prevent disappointment. Our project learned that our main delivery tool – Google Earth Pro, performs differently on Apple systems, and cannot be used at all with Google Chromebook systems.
Volunteers going off task
With a larger volunteer group be prepared for a proportion to not rigidly stick to the prescribed task or instructions (e.g. we asked that each volunteer searched a parish systematically, but some could not work in such a rigid manner). We recommend embracing unique qualities of each volunteer if possible (e.g. some will be adept at rapid scanning of images, some at very detailed analysis), be prepared to be flexible and assign revised tasks that suit individual characteristics.
Communications overload
Be prepared for a surge in email traffic from volunteers enthusing over their discoveries. It is important to keep expectations over the number of detailed replies and reply time reasonable. Ask prolific emailers to consolidate reporting into a weekly or fortnightly email, and to ask for help in different threads.
Volunteer drop-off
Expect the number of active volunteers to wane over time. People’s enthusiasm can change rapidly, as can their availability. Realise that there will be short-term volunteer engagements as well as long-term commitments. Do not take it to heart when volunteers ‘drop out’.
8. Useful links
Except where noted and excluding company and organisation logos this work is shared under a Creative Commons Attribution 4.0 (CC BY 4.0) Licence
Please attribute as: "Image analysis for heritage mapping, using open-access software and remote sensing data (2023) by University of Exeter supported by The National Lottery Heritage Fund, licensed under CC BY 4.0
