Development

Fun with free maps on the free desktop

Playing with open map data can be a fun pastime. Creating and editing open data can be not only fun, but also a boost for free data to go along with free software. Whether you want to view open map data or edit it, there's no shortage of applications that run on Linux and work well with OpenStreetMap (OSM) data. Here's a look at some useful mapping applications for displaying and editing open map data on the Linux desktop.

Emerillon

One of the newest map viewers for the free desktop is Emerillon. Announced last October, the Emerillon project is meant to be a simple, open, and extensible map viewer that allows users to browse open map data, search maps, and "placemark" (bookmark) locations for later reference. Even if the project itself is new, the name is laden with history. The name has a dual meaning, as "Émérillon" is a name for a type of falcon once used for falconry and it is the name of one of French explorer Jacques Cartier's boats.

Emerillon is still in early development. The project hasn't tagged any releases as "stable" yet, but tagged a development release in early January. If compiling the package doesn't sound appealing, Matt Trudel has put together an Ubuntu package of the 0.1.0 release for Ubuntu 9.10.

The interface is clean and easy to use, and the map rendering is very attractive. Once Emerillon is loaded, just use the mouse to drag to the location you'd like to see or search for a location. Zoom in and out using the mouse scroll wheel or magnifying glass icons on the top location bar. There's not a lot to the interface and it shouldn't take any time at all to start using Emerillon. It doesn't require manual intervention to get map data as it automatically uses OSM data. Emerillon can be a bit slow rendering, but not overly so. It might take five to 10 seconds to render the map when selecting a new location or zooming in or out. It's not quite as speedy as Marble, but it gets the job done.

Despite the relative newness of Emerillon, it is worth a look if the only requirement is a stable OSM viewer. It's a usable map viewer for browsing standard OpenStreetMap street views, public transportation maps, cycling maps, or terrain data. To get routing data, it is possible to copy the current location to Google Maps or Yahoo! Maps to generate a route. Emerillon doesn't have any features yet for printing or exporting maps.

Most of Emerillon features are derived from plugins. The functionality is fairly limited otherwise for now, but the plugins page includes a number of ideas for future development — including routing data, working with GPSes, and integration with Telepathy to allow sharing of location data.

Marble

Marble is one of the best-known map-viewers for Linux. Marble works with a number of different data sets, including OSM, and a number of custom maps including historical maps from the 1700s, satellite views of the Earth, temperature and precipitation, and even maps of the Moon and Venus. While the navigational value of having maps from the 1700s or of Venus is scant, there's a lot of educational value in being able to display other celestial bodies and maps from different eras.

Marble presents its maps, dubbed "themes" in the Marble interface, using a globe projection by default. Users can switch to a flat or Mercator projection if they prefer. In addition to displaying map data, Marble can also display photos tagged with geographic data or Wikipedia articles associated with a location if the Photos and Wikipedia plugins are enabled.

After opening Marble, it will zoom in on the user's "home" location if set, on the last theme used. The home location is set by right-clicking on the map view and choosing "Set Home Location." Navigating around the map is done by clicking and dragging, or using the mouse scroll button to zoom in and out on specific areas of the map. Marble features an interesting animation when performing searches. When using the Search sidebar, type in a city name or location and Marble will zoom out to a full Earth view and then zoom in again on the search location.

Marble can be used to measure the distance between two locations on the globe by adding "measure points" with the context menu. The total distance will be displayed in the map overlay. Users can copy and print map views from Marble for later use, but it doesn't provide any way to "save" the views for later.

By itself, Marble is primarily geared for educational use and displaying different parts of the globe. It's not designed for creating route maps or giving any kind of street directions. You can view maps designed for navigation, like the OSM Cycle Map, but Marble doesn't do point A to point B directions. However, Marble is also an embeddable widget that can be used in other Qt applications. This means that any application that needs to display map data can include Marble and rely on it for rendering.

Since Marble has been around for quite some time, most Major Linux distros include it in their package repositories. It's available under the LGPLv2, and additional maps are available from KDE's "Get Hot New Stuff."

Merkaartor

If viewing maps isn't enough, why not try editing them? Merkaartor is an application for editing OSM maps. It actually works with several formats, beyond OpenStreetMap. Merkaartor will import OpenStreetMap, GPS Exchange Format, KML Files, Noni GPSPlot, and several others. The export formats are a bit more limited, with OpenStreetMap, GPS Exchange Format, and KML supported.

Merkaartor will open any of the supported formats, or download data from OSM. There's a limit on how much data Merkaartor will download at any given time, so it may take a few tries to get the request right and get all of the desired map data. Once it has data, users can edit map data and upload it to OpenStreetMap (assuming the user has an OpenStreetMap account).

It can also provide an interesting look into the existing OSM data, and will show which users uploaded specific data. Assuming a bit of experience with editing map data, Merkaartor seems easy to get started with and use. It's not for casual OpenStreetMap users, but should be a valuable tool for contributors. For viewing maps, Merkaartor isn't as usable as Marble or Emerillon and doesn't render the maps quite as attractively.

Merkaartor not only works with standard map formats, it will also render maps to SVG and Bitmap formats. This could be useful if you want to include OSM data in a publication, or just whip up a quick map with directions to your next party.

Conclusion

What would be nice to have is an application that makes it easy to simply punch in a few addresses and create a route. While a few free and open source desktop apps exist to work with GPSes or GPS data, they're not particularly intuitive or easy to get started with. The state of editing and viewing OSM data is pretty good on Linux, but there's still much to be desired for using that data to get from point A to point B.

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