GIS Tips – Referencing spatial data

One of the most important and vital components in creating any GIS output, be it an online map or a simple image to provide the boss, is also one of the most legally dangerous….Referencing & licensing your data sources.

This is scary ground, some people over-reference and end up writing a novel (taking away half of the map) and others miss the most simple reference like Google Earth or ESRI. I don’t blame them, it’s a subject not covered in most books and then when you download spatial data you find that there isn’t any written text to follow.

Hopefully I can shed some light on what to do and how to correctly reference data, this is by no means definitive (question is, where is the legal line?). So, here goes…..

Poor example:

In the example above, can see that national conservation designations have been used but are not referenced, where did the data come from? What licence do they have to reproduce the data? One would assume that Natural England designations were used and contrary to belief, even though this data is in the public domain, it is still licensed and requires reference:

From a legal standpoint the above map could be called into question, whereas the map below, even though it is pure simplicity is absolutely spot-on, fully referencing the sources:

So, what is the best practice? Obviously as map makers (whether interactive, static or other) we need to ensure we are legal and provide the full story to our audience, which means explaining where the data is sourced


You can see how, in the image above, the correct licensing is used for all the layers used within the map, also the data source is referenced, this is so that any spatial data which has no licence provided can still be referenced. This makes it clear where all the spatial data has been sourced from, allowing the audience to make up their own minds over whether the best data has been used.

Okay, here are my recommendations for referencing spatial data in your maps;

Data from Media provided to you, provided online or via FTP

  • If a licence has been provided, reference the licence in full at a minimum of 8pt text and also reference each data provider for clarity.
  • If no licence is provided firstly, if possible, contact the provider! This data may be heavily restricted and posted up by someone with a grudge or little care for the legalities.
  • If you HAVE contacted the company or have no way to obtain any permissions, a minimum of;  “Reproduced from spatial data sourced from [provider]”, year and any permissions granted. The source provider should be clearly stated and where possible the link to the data. All text should be a minimum of 8pt.

An example of data quoted without licence might be:

Reproduced from spatial data sourced from Blue Marble, 2013. Data source:

Do I need to put licenses on web maps?

Yes, treat a web map as you would a printed map. You are still responsible for referencing your material, not only that, it is good practice to provide your sources.

Ways to reference the spatial data

You have designed a work of art and thrilled to put it up on the internet for all to see……only there is no way to start putting text all over it due to the system you are using or that it is way too complicated to add in the interactive map, so what do you do?

Most importantly, DO NOT neglect the licensing, having spoken with many of the big data providers, they are more concerned with being referenced than they are in how you put the reference in. I recommend that if you cannot physically put the text within the map, put it in text below the map, though make it clear that this is the license for the data and be clear.

One more consideration…

One last thing to consider is your symbology….yes, really! You may find with some data that there are restrictions or requirements applied to the colours or display of the data you are using. Simple to overlook but ultimately still a point for consideration.

Examples of Spatial Data licenses often overlooked

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