Crowdsourcing Archaeological Data with Participatory GIS

GIS Contributor

This is an expanded version of a talk Ed Jones, co-founder of Humap, gave at GeoMob in London on 16th March 2022.

I’m the co-founder and co-director of a geospatial storytelling platform called Humap, and there are two primary ways people use our platform. 

One way is as a presentational tool for users to explore data which is already extant: a publishing platform for projects like the Wiener Holocaust Library’s Refugee Map. We think of these projects as ‘summative’ – that is, the output of a curatorial process. 

The second is the actual creation of new content: using Humap to allow people to tell their own stories or interpret the world around them. We think of this as a ‘formative’ use of  Humap, and that is the subject of this article. 

Of course, many projects do a mixture of the two – Layers of London mixes crowd-sourced and curated content. 

How is this relevant to archaeology and GIS? 

Everywhere we go, there’s history under our feet. It’s the job of archaeologists to find,  record and preserve artefacts from the past. But how do they know where to dig? There are  a wealth of techniques for identifying locations of interest, but up until now they’ve all  relied on experts to interpret existing data and draw conclusions. 

We were chatting with an archaeology company called Digventures about their work in community engagement, and they set us an interesting challenge: would it be  possible for lay-people to make a significant impact on the quality of data about what exists  under the ground? Could their team of volunteer archaeologists (whom they call  ‘Pastronauts’) improve the quality of official archaeological data, and add to our knowledge  of the ancient landscape? 

HER data (and how to access it) 

Every area of the UK has an Historical Environment Record (HER). It’s an openly available  official source of data about what’s known to be under the ground: crucial for property  developers, planners, municipal authorities, utilities, environmental organisations, historians and archaeologists.

A screenshot showing a data record for a geographic feature that is shaded light green against a dark green-yellow background.
Figure 1: An example HER record interface.

The quality of HERs vary enormously, and in all cases, it’s incomplete. To compound the  problem, accessing this data is really hard – in the best cases, HERs are available online via antiquated web interfaces with little regard for the end-user’s needs and experience.

Screenshot showing a very small street map contained within an interface.
Figure 2: A second example HER record interface. 

Improving the user’s experience was going to be really important if people were going to be  able to add to this data. 

Improving the quality of HER data with LiDAR 

How are we expecting people to improve the quality of HER data anyway? The answer lies in LiDAR – a method of 3D scanning the ground using lasers, and then computing different  interpretations of this data to build up a picture of the ground surface. 

Combining existing HER data, LiDAR scans of an area, and historical and current maps, it’s possible to identify features on the ground which correspond accurately to sites of  archaeological interest. 

The challenge for us was to build something which allowed non-experts to do this, what Digventures co-founder Brendon Wilkins described as a “participatory GIS” platform.


Our solution is Placemaker – a tool to allow users to draw accurately on a map, without the need to download complicated software or have prior GIS experience. 

Placemaker allows Digventures to present a series of reference layers of data (LiDAR, an  historical map, and existing HER datasets) on a map, and makes drawing accurate shapes on the map as easy as using something like Microsoft Paint. 

Screenshot showing the Placemaker's interface with a green geographic feature against a gray background.
Figure 3: Placemaker’s layer interface.

The shapes on their own wouldn’t be very useful, so alongside this, Pastronauts logged what  it was they were looking at, as part of a set of structured data associated with each shape.  The data was then saved in PostGIS for easy access. 

Here’s how it works: 

1. The project area is divided into squares of about 1 KM on each side. That’s a decent size  for a person to do a thorough job (without losing the will to live).

Screenshot of a map with blue grid overlay and a red outline of a geographic area.
Figure 4: A pastronauts view of the eligible square kilometers.

2. You pick a square which hasn’t been started, and start assessing your square across all  the overlays in the sidebar. The pastronauts were mainly looking for obvious signs of  archaeological interest – ditches, ridges, quarries etc. 

A screenshot showing a transparent green polygon on top of a purple polygon with a dark grey 3D geographic background.
Figure 5: A pastronauts view of the polygon editing interface. 

4. Mark your areas of interest and identify them in the metadata

A screenshot of a map editing interface with a dark gray 3D geographic background and yellow polygons.
Figure 6: A pastronauts view of the metadata interface. 

5. Done! 


The outcomes were really exciting, and surprised even the project team: 2,361 new sites were identified (60% increase in documented archaeology).

An audit of data quality (on fidelity, accuracy and completeness) shows that the data was  94% accurate (as opposed to HER data which is usually about 88% accurate).

100 people with limited or no experience in archaeology or geographic computing systems  produced professionally valid results, and earned significant sectoral experience.

Why does this matter? 

For all professions involved in changing the landscape or built environment, historical  records are crucial. Anything that can add to the quality and breadth of the data available to  them is really important; moreso if it also involves a reduction in cost and effort. 

We’re excited that Placemaker has been able to simplify and democratise tasks which were  previously complicated and reserved for professionals. This project took place during the  height of the COVID-19 pandemic, and Placemaker isn’t just useful for archaeology. There are loads of other use-cases for drawing and annotating on maps, some of which we’re looking forward to sharing in the future.

Interest piqued? 

If you’d like to know more about Placemaker, get in touch with us at

About the author

Ed Jones is the Co-founder and GIS & Technology Lead for Humap. He has a degree in education, a background in project management and business analysis,  and has been developing software for the web since 2002. His responsibilities at Humap  include technical direction, platform security and resilience, and client onboarding. He has  worked for companies as diverse as national radio broadcasters, digital consultancies and a  large e-commerce retailer. 

As a founder of Humap, Ed has overseen the development of the entire platform, and  continues to ensure its security and functionality. He is technical consultant on every project, and leads on technical design, development and quality assurance, as well as client onboarding and consultancy. 

Website | Twitter | LinkedIn

Photo of author
About the author
GIS Contributor
Guest articles from GIS professionals. Authorship information is listed at the bottom of the articles.

Free weekly newsletter

Fill out your e-mail address to receive our newsletter!