Digitising historical maps

By July 18th 2017

How do you go about recording the wealth of information in a historic map, making it available in a digital form, and how can it be funded?

I recently managed a project to capture nearly half a million boundaries from historic Tithe Maps in Devon. The maps, dated from the early 1800’s are often the earliest complete maps of parishes and show details such as land ownership and cultivation.

When visiting the Heritage Centre I was shown the original hand drawn maps. It struck me just how fragile they were and how easily they could be lost or damaged. The detail was tiny and even a little degradation could lose information that could not be found anywhere else.

Happily, they have all been photographed at a high resolution and their information captured into an intelligent mapping database which will allow internet users to navigate around the maps and interrogate the boundaries and related data.

But it’s not just maps that are hundreds of years old that hold unique information. Even maps dating back to the 1960s and 70s have often never been captured. Maps of old planning applications for instance, may still be sat in the basement of a Local Authority office with no digital copy, let alone any way of searching or viewing the maps and related data on a computer or mobile device.

Scanning the map

The first process in capturing historical maps is to make a detailed image of the map which can be kept digitally in multiple locations. There are various ways of achieving this:

  • Scanning the maps using a large flatbed scanner which can be bought to the location of the map archive so they don’t need to leave the building
  • Photographing the maps onsite and stitching the images together in post processing
  • Using specific equipment for scanning maps off slides or microfiche where the originals are not available
Historical planning map of Welwyn Garden City

Historical planning map

Spatial referencing

The next stage in digitising historical maps is to spatially reference the images of the historical maps (often referred to as georeferencing).

This process means fitting your images to modern mapping in a Geographical Information System (GIS). If your maps have continuous coverage, they could be merged into a single mosaic. This stage could allow your maps to be put online into a Google Maps style application. Users can view your maps alongside other mapping information and carry out simple procedures such as measuring distances or areas.

But why stop there? It’s likely your maps have useful detail such as boundaries and reference numbers. Without searchable or clickable access to this information, is your mapping application of real use?

Data Capture

Data capture is the process of capturing lines or areas of specific features or boundaries on a map as coordinates within a GIS, and attributing them with information such as a unique reference number.

Once complete, these can link to other information such as textual material or photographs. You can keep your spatial database in an internal GIS within your organisation, or publish it online to allow users to query the map data and related information.

Digitising historical maps

Tithe boundaries captured as intelligent spatial information in a GIS system

Historic maps can be scanned, spatially referenced and captured to allow important information which may otherwise be hidden away or at risk of being lost forever, to be shared within an organisation or the public. None of the tasks involved in digitising historical maps have to be particularly expensive and you may even be able to organise funding for your project from The Heritage Lottery Fund (HLF).

Lovell Johns are a mapping company who can organise all the stages of digitising historical maps and publishing GIS databases using online mapping solutions.

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