# jonwit's Diary

## I am Learning Overpass Turbo and OpenStreetmap.

Posted by jonwit on 24 September 2015 in English (English).

I thought it would be fun to create a little test project to more familiarize myself with OpenStreetMap and Overpass Turbo

Note, this is a work in progress. Any tips will be useful

I read a few mentions on how some organizations have used OpenStreetMap to calculate population density. I figured I would give it a go.

## 1. Create a OpenStreetMap Map

First I created a simple map interface with needed tools and legends using Mapbox Tutorials. I then put up a sample code page on github. Population Count Test Page

## 2. Count the Number of Different Buildings in OpenStreetMap

The next step(s) would then be to extract the Houses and other buildings from the dataset. An example would be. Extract Houses with Overpass Turbo `( // query part for: “House” node["building"="house"]({{bbox}}); way["building"="house"]({{bbox}}); relation["building"="house"]({{bbox}}); );`

Set OverPass Query to only count and put into a json file

Count of Elements

`out count;`

This creates a JSON file like this: ```{ "count": { "total": 7402, "nodes": 6214, "ways": 1187, "relations": 1, "areas": 0 } }```

## 3. Load data from json into the html

possibly with jquery ```\$.getJSON('/json/somedata.json', function(data) { // do something with the data here });```

## 4. Housing Unit Method Summary Equation

From a simple search online I found a few calculations.

1. Possible Calculation Housing Unit Method Summary Equation Population = Population in Group Housing + Occupied Units * average household size
2. Fine-resolution population mapping using OpenStreetMap points-of-interest 3.Measuring Completeness of Building Footprints in OpenStreetMap over Space and Time

## 5. Display on Map

Project Page

Here is the Github page if you would like to contribute. Population Count Test Page

Have a good day!!