We wrote in yesterdays blog about the importance of data: the fuel which powers the engine. Today we will discuss sources of data.
Mobile GIS: Finding Data
In map terms published data is called layers. In all mobile mapping apps map layers overlay (rather like an acetate) a basemap. This can be a satellite image, vector roads, topo etc. Many have started flying and photographing areas using drones. Often using this data as their basemap source. Below is a satellite image used in our GeoAppSmart mobile ArcGIS app:
Here is an interesting article on 20 FREE Satellite Imagery Data Sources.
For mobile users basemaps provide a reference layer. Operational layers are those which sit on-top of a basemap. There are 3 types; point, line and polygon. Each is often representative of a real world feature (park, valve, water line, house, river, flood plain etc). A mobile web map is a mash up of different operational layers. This is the data needed by field staff to get their work done. Usually this maps mash up is made up of data sourced from 2 places. First your published data. This is data you either own, or have created. Three common sources are:
- Desktop Data Generation– If you have experts who know desktop applications like ArcMap and ArcGIS Pro. It is likely you have published at least some of your data as map layers to ArcGIS Online directly from a desktop product. Our resident GIS real estate expert often uses ArcMap to create new layers: retail outlets in Salt Lake, billboard layer, parcel data etc.
- Shapefiles – Many organizations still have their data locked up in shapefiles. These can be published directly to ArcGIS Online and shared with mobile users.
- Spreadsheets – If a spreadsheet contains address or lat/long in the correct format. Simply saving the spreadsheet to a CSV then allows this data to be published to ArcGIS Online. Geocoding, or converting an address to a mappable feature, is done on the fly.
Field staff may find themselves editing your data to keep it up to data and accurate.
The second source of mobile map layers is public data. Finding public data can require some detective work, but there is gobs of free public data available particularly in the US. Take a look at a government web site and find the mapping or GIS page. Usually you will see a map viewer. Below is the Salt Lake Assessors interactive map.
The layers you see are usually public layers you can use in your mobile app. There is a clever trick you’ll need to know – nothing nefarious – to discover each data layers source. In some states there are public agencies which provide data. In Utah we have the AGRC which provides a rich source of map data in many formats.
There you have it, a whistle-stop tour of mobile ArcGIS map layer sources. I cannot overstate how important it is to assemble your data at the start of any project. This is the foundation of your mobile ArcGIS base. Data discovery and creation is as much art as it is science.
Contact us on 801-733-0723 if you need data help.
Read our free white paper ‘ArcGIS Deployment Guide’, which provides a road map for getting started and moving forward with ArcGIS Online.
Author: Matt Sheehan
Matt Sheehan is a Principal at WebMapSolutions. Matt evangelizes GIS and location intelligence around the world through keynotes, articles, tweets and his books. Follow him on Twitter: