TagGeoJSON

How to download data from ArcGIS MapServers using your computer’s command line

A lot of geospatial data (GIS) is stored on ArcGIS MapServers, which is part of the Esri “stack” of products that municipalities use to manage and publish GIS data. And a lot of people want that data. If you have ArcGIS software on your Windows computer, then it can be pretty easy to plug in the map server URL and manipulate and extract the data.

For the rest of us who don’t have an extremely expensive license to that software, you can use a “command line” tool (written in Python) on any computer to download any layer of GIS data hosted on the ArcGIS MapServer and automatically convert it to GeoJSON.

You’ll need to install the Python package pyesridump, from the OpenAddresses GitHub repository, created by Ian Dees and other contributors.

Installing pyesridump is easy if you have pip installed, using the command pip install esridump.

The next thing you’ll need is the URL to a layer in a MapServer, and these are not easy to find.

Finding data to download

I can guarantee the county where you live has one. Before you continue, check to see if your county (or other jurisdiction) has the “open data portal” add-on to their ArcGIS stack.

Here are links to the open data portals enabled by Esri for Lake County, Illinois, and Broomfield County, Colorado). This is much easier to browse and find data to download (in shapefile and other formats) and you can skip this tutorial.

I don’t have a good recommendation to find the MapServer URL, though. A reader suggested looking for MapServers for jurisdictions around the world by looking through Esri’s portal of open data called ArcGIS Hub. Once you locate a dataset you want, you can find the MapServer URL under About>Data Source on the right side of the page.

I normally find them by looking at the HTML source code of a MapServer I already know about.

For this example I’ll use one of the GIS layers in the Cook County, Illinois, election service MapServer – here’s the layer for the Cook County commissioners districts.

Fetch the data

Once you have the URL the command is simple:

esri2geojson http://cookviewer1.cookcountyil.gov/ArcGIS/rest/services/cookElectnSrvc/MapServer/11 cookcounty_commissioners.geojson

  • The first term, esri2geojson tells your computer which program to load.
  • The second term is the URL of the MapServer URL.
  • The third term is the filename and location where you want to store the file. I prefer running the command “inside” the folder where I want the file to be stored. You can also specify a full path of the file. On a Mac this would look like ~/Users/username/Documents/GIS/projectname/cookcounty_commissioners.geojson

After you enter the command into your computer’s terminal, press enter. esri2geojson will report back once, after it finds and understands the MapServer URL you gave it. When it’s done, the command will “close” and your computer’s terminal will wait for the next command.

Do you have questions, or need some help? Leave a comment below.

How to extract highways and subway lines from OpenStreetMap as a shapefile

It’s possible to use Overpass Turbo to extract any object from the OpenStreetMap “planet” and convert it from a GeoJSON or KML file to a shapefile for manipulation and analysis in GIS.

Say you want the subway lines for Mexico City, and you can’t find a GTFS file that you could convert to shapefile, and you can’t find the right files on Sistema de Transporte Colectivo’s website (I didn’t look for it).

Here’s how to extract the subway lines that are shown in OpenStreetMap and save them as a GIS shapefile.

This is my second tutorial to describe using Overpass Turbo. The first extracted places of worship in Cook County. I’ve also used Overpass Turbo to extract a map of campgrounds

Extract free and open source data from OpenStreetMap

  1. Open the Overpass Turbo website and, on the map, search for the city from which you want to extract data. (The Overpass query will be generated in such a way that it’ll only search for data in the current map view.)
  2. Click the “Wizard” button in the top toolbar. (Alternatively you can copy the code below and paste it into the text area on the website and click the “Run” button.)
  3. In the Wizard dialog box, type in “railway=subway” in order to find metro, subway, or rapid transit lines. (If you want to download interstate highways, or what they call motorways in the UK, use “highway=motorway“.) Then click the “build and run query” button.
  4. In a few seconds you’ll see lines and dots (representing the metro or subway stations) on the map, and a new query in the text area. Notice that the query has looked for three kinds of objects: node (points/stations), way (the subway tracks), relation (the subway routes).
  5. If you don’t want a particular kind of object, then delete its line from the query and click the “Run” button. (You probably don’t want relation if you’re just needing GIS data for mapping purposes, and because routes are not always well-defined by OpenStreetMap contributors.)
  6. Download the data by clicking the “Export” button. Choose from one of the first three options (GeoJSON, GPX, KML). If you’re going to use a desktop GIS software, or place this data in a web map (like Leaflet), then choose GeoJSON. Now, depending on what browser you’re using, a couple things could happen after you click on GeoJSON. If you’re using Chrome then clicking it will download a file. If you’re using Safari then clicking it will open a new tab and put the GeoJSON text in there. Copy and paste this text into TextEdit and save the file as “mexico_city_subway.geojson”.
Overpass Turbo screenshot 1 of 2

Screenshot 1: After searching for the city for which you want to extract data (Mexico City in this case), click the “Wizard” button and type “railway=subway” and click run.

Overpass Turbo screenshot 2

Screenshot 2: After building and running the query from the Wizard you’ll see subway lines and stations.

Overpass Turbo screenshot 3

Screenshot 3: Click the Export button and click GeoJSON. In Chrome, a file will download. In Safari, a new tab with the GeoJSON text will open (copy and paste this into TextEdit and save it as “mexico_city_subway.geojson”).

Convert the free and open source data into a shapefile

  1. After you’ve downloaded (via Chrome) or re-saved (Safari) a GeoJSON file of subway data from OpenStreetMap, open QGIS, the free and open source GIS desktop application for Linux, Windows, and Mac.
  2. In QGIS, add the GeoJSON file to the table of contents by either dragging the file in from the Finder (Mac) or Explorer (Windows), or by clicking File>Open and browsing and selecting the file.
  3. Convert it to GeoJSON by right-clicking on the layer in the table of contents and clicking “Save As…”
  4. In the “Save As…” dialog box choose “ESRI Shapefile” from the dropdown menu. Then click “Browse” to find a place to save this file, check “Add saved file to map”, and click the “OK” button.
  5. A new layer will appear in your table of contents. In the map this new layer will be layered directly above your GeoJSON data.
Overpass Turbo screenshot 4

Screenshot 4: The GeoJSON file exported from Overpass Turbo has now been loaded into the QGIS table of contents.

Overpass Turbo screenshot 5

Screenshot 5: In QGIS, right-click the layer, select “Save As…” and set the dialog box to have these settings before clicking OK.

Query for finding subways in your current Overpass Turbo map view

/*
This has been generated by the overpass-turbo wizard.
The original search was:
“railway=subway”
*/
[out:json][timeout:25];
// gather results
(
// query part for: “railway=subway”
node["railway"="subway"]({{bbox}});
way["railway"="subway"]({{bbox}});
relation["railway"="subway"]({{bbox}});
/*relation is for "routes", which are not always
well-defined, so I would ignore it*/
);
// print results
out body;
>;
out skel qt;

How to convert bike-share JSON data to CSV and then to shapefile

Update January 4, 2013: The easiest way to do this is to use Ian Dees’s Divvy API as it outputs straight to GeoJSON (which QGIS likes). See below.

For Michael Carney’s Divvy bike-share stations + Census tract + unbanked Chicagoans analysis and map he needed the Divvy station locations as a shapefile. I copied the JSON-formatted text of the Divvy real-time station API, converted it to CSV with OpenRefine, and then created a shapefile with QGIS.

Here’s how to create a shapefile of any bike-share system that uses hardware from Public Bike System Co based on Montréal and is operated by Alta Bicycle Share (this includes New York City, Chattanooga, Bay Area, Melbourne, and Chicago): Continue reading

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