Transforming Lists into Maps:
Using Online Tools to Geocode Non-Spatial Files
With the increase of popular online GIS tools, non-GIS users are largely utilizing the technology for social and entertainment purposes. Without easy access to or even interest in desktop GIS software, many are finding interesting and exciting GIS-related activities to do on the web. Many have experimented with Google Mashups, and have added their own place marks with resourceful information attached. Some have added personal photos and freely share them with the world. In fact, it's the sharing of resources that are attracting users to mapping technology. Google Maps for example, is a world shared by the world for the world.
As a GIS user, Iím finding it interesting to watch GIS technology evolve on the web. What used to be only possible to do on a desktop system, by a trained GIS user, seems to be so easy to do on the web by novice users. I started thinking about the ways expert users utilize a GIS and whether similar results can be obtained with online technology. Can novice users, for example create their own geospatial files to use on the web? Are they limited to Google Mashups, or can they create personal files, update them and view them spatially in online mapping programs or by using free downloadable GIS viewers?
Using Textual and Tabular Files
Everybody creates, maintains or uses lists of information on a daily or weekly basis. A list of errands to run, a list of phone numbers and addresses, sports schedules, a vacation itinerary, genealogical records, etc. In many cases, this list can be mapped and used to determine not only locations but to find best driving directions, most efficient order of events, and patterns normally hidden within the tabular information. As an example, I took some of the research that Iíve started collecting about my immediate neighbours and their homes. When was their house built? How many owners have there been and in what year did the homes change hands? I wanted to have this information mapped in a GIS program so that I could discover the details of the home by simply clicking on the house of interest. To do this, I needed to assign geographical coordinates to my table, a process called geocoding. GIS programs look for spatial coordinates, so I needed to determine the latitude and longitude of each house using street information that I had.
|Image 1. Example of information in tabular format
Geocoding by Street Address
To determine the latitude and longitude for each property, I used a really simply and accurate free online tool available at http://www.batchgeocode.com/. This geocoder tool supports North American and European addresses. I entered the contents of my table, and it returned with the spatial coordinates. It also simultaneously displayed the contents of my table in a map form.
This information can be viewed more permanently in Google Maps or Google Earth, because batchgeocode offers the creation of KML files from the geocoded tables. Users who want to manipulate or query their geospatial files can add them into GIS programs that support KML. TatukGIS Viewer or Quantum GIS for example are both free GIS software programs that support KML files.
Many users may be interested in using batchgeocode for Google Mashups. When the address is known, but the actual geographical location isnít quite familiar to you, this online tool will set you up conveniently and quickly.
Details about batchgeocode.com
Batchgeocode is a free online product that locates addresses, calculates distances and geocodes your spreadsheets. Based on Yahoo! Geocoding API, it will accept any North American and European address with a street name and number and will geocode the addresses to provide you with its latitude and longitude in the WGS84 coordinate system. Your updated spreadsheet can then be mapped using either desktop GIS software or Google Earth. You can also take advantage of the productís calculation tool to determine distances, and get quick driving directions as well. Geocoding your tabular information is a quick 6-step process and is done in a matter of seconds. Whatís unique about batchgeocode is that unlike other geocoders, it does in fact support batch processing Ė it maps all of your addresses simultaneously.
Not all files have address information available. Sometimes the locations we are interested in are very specific, and geocoding to a street number wonít provide us with accurate coordinates. For example, if Iím interested in creating a map of a college campus, using a street address will not provide me with the coordinates for each building. The table below shows information about the three major libraries on campus at the University of Waterloo. Some of the libraries do not have their own building, so exact placement of the location of the library within the building would be necessary.
In order to map this information, I need to determine the latitude and longitude. Google Earth does a wonderful job with this. By using the Placemark tool, the coordinates are made readily available. A KML file can be created at this time in Google Earth as well. If the user wishes to continue working with the original tabular file however, the latitude and longitude can be recorded in the table, and then an Excel to KML converter program can be used to create the KML to be used in supporting GIS programs. A KML generator program can be found at http://www.earthpoint.us/ExcelToKml.aspx. This product will convert a Comma Separated Value (.csv) file into a KML file.
Details about Earth Point
Earth Point is a real estate site from Idaho. The Excel to KML converter tool available from this site was created so that users could view real estate listings on Google Earth. Itís a simple converter, supporting xls, xlsm, xlsb (Excel), csv (comma separated values) or txt (tab delimited) files. The converter was designed in such a way that the Latitude and Longitude values must be present in the first two columns of the table. The third and fourth column must be named ďNameĒ and ďDescriptionĒ in order for the tabular information to be successfully converted and retained in the KML files. There is also the option to select a symbol for the icon. Every row in the file can have individual and unique icons. There are over 250 to choose from. This converter provides a quick way to transfer files into kml format, but one drawback is that it limits the information available in the table.
- Published September, 2008