The GMAPCreator is a freeware Java application designed to make thematic mapping using Google Maps from Shapefiles containing polygon areas, lines and points linked with attributes and automatically generates a working Google Maps from the data. It creates tiles from user entered Shapefiles that are then overlaid on a Google Map. This is particularly effective if you have a large amount of data you want to map and you also want to protect your data. Because the created maps are built from pre-rendered tiles the raw data is never stored on the Internet. This then is a safe way of sharing a map without giving away the raw data used to create it.
The basic method for creating Google Maps websites is as follows:
- Start the GMapCreator program.
- Click on ‘File/Open’ and load in a shapefile.
- Use the drop down box in the map preview window to choose an attribute from the shapefile.
- Click on the ‘Cols…’ button and pick some colours, threshold values and descriptions for the areas in the shapefile (see: Colour Thresholds).
- Either use the ‘Maximum Zoom Level’ slider to limit the zoom level, or use the ‘Zoom In’ button in conjunction with the ‘Limit to preview’ check box to limit the geographic area created. Whatever zoom limits and geographic limits are chosen, the ‘Tile Count’ will show the number of tiles that will be created when ‘Create’ is clicked.
- Click on the ‘Create’ button and a dialog showing the number of tiles and the directory will be shown. Click on ‘OK’ to begin the creation process.
- Now in Windows, go to the directory containing the shapefile, where there will be an html file with the same name. Double click on this and the map will load.
- As a final step, use the ‘File/Save Settings…’ option to save the current setup to file. This way, all the zoom levels, colours and thresholds will be saved and can be loaded with the ‘File/Load Settings…’ option later.
- In order to publish the site on the web, the html file and the directory containing all the tiles called ‘shapefilename-tiles’ need to be copied to a web server. The API key will also need to be set correctly in the html file.
GMapCreator can be downloaded from the UCL Centre for Advanced Spatial Analysis. You do need to create a MapTube account to download the software.
