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How Leicester Police might have created their helicopter map


lec-heli-thumbYesterday, people on twitter noticed how Leicester Police is using a Google maps mashup, to display recorded incidents of helicopter usage in the city.

The map includes incidents from the last three months, no say about whether this will change or not. You can browse through the incidents based on where and when they happened.  A drop down menu lets you select between the force you want to see and in which time period. And because it is a Google map, you can also use the zoom functions to navigate to a specific neighbourhood.

How this is done

There is no way of knowing exactly how this was done without talking to the developers, but we can make a pretty good guess, or at least provide an alternative method.

For starters you need the data. You can see from the map that there are 5 elements of data involved in each incident: Where it happened, the incident no., the time span of the operation, the reason and the result.

Police Helicopter in Leicestershire

All this would be standard information that have been filed after each incident and stored in the police database. The easiest way to imagine a database is like a spreadsheet. It’s made up of tables, rows, columns and cells.

Now this information is extracted from the database and translated into a language that Google maps can understand. The final data is simply stored in a document that Google maps can read. And every time something new goes into the database, the document will automatically update and so will the map.


How the data might have been entered into the spreadsheet/database

It is actually not as hard as it looks and below, you can see an example of how you might have accomplished this. The spreadsheet/database containing the information (above), and the final document that is parsed to Google maps (below). The only main difference is that the place name, in this case Manor Road,Oadby, has been converted into actual coordinates. This is easily accomplished by using a service like Yahoo Pipes or other similar tools.

The same data in a document that Google maps can understand

The same data in a document that Google maps can understand

In a later post I will show you how you can turn your own spreadsheet into a map using this process. A little bit like we’ve done with the map of hyper-local brum blogs.

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