I just found this in my "Drafts" mail folder. Apparently, I never sent it. My apologies to all, and especially to Richard, the presenter. He deserves better. Sorry!
Original message follows: I was pleased to be able to attend the Sep 2008 meeting of MerriLUG, held at Martha's Exchange in Nashua, NH. Taking place on the Thr 18 Sep, about 15 people attended. The speaker was Richard Weait, who was presenting on OpenStreetMap. == What and why == So what is OpenStreetMap? Well, I'd describe it as "the spirit of Wikipedia brought to Google Maps". It's a giant database of map data, particularly street map data. Like many other useful forms of information, maps have traditionally been copyrighted, controlled by a small community (cartographers), and expensive. OpenStreetMap (OSM) is an open, Free Content database of map information. Anyone can add, amplify, or modify the data. The reasons why are, I expect, well-known to this group: Lower cost. Freedom to use it any way we want. Contributions from across the globe. Details from localities that corporations don't find profitable. Enabling creative combinations of ideas. And so on. The choir is familiar with the sermon, I presume. == Licensing and content == The OpenStreetMap database is currently licensed as CC-by-sa (Creative Commons Attribution Share Alike). This was deemed the most appropriate license of the major ones available, but is not really any appropriate license for a collection of facts (which any map dataset is). An effort is underway to create a more appropriate license -- a Free Content license for databases. More: <http://www.opengeodata.org/?p=262> Because OSM is Free Content, it cannot accept data encumbered by copy restrictions. They can't just copy data from Google Maps, MapQuest, etc. They've recently completed a big import from the US Gazetteer (public domain as a work of the US Gov), but government map data in many jurisdictions is not so lucky. == Basics == You can get started just by opening up <http://www.openstreetmap.org/>. The UI should be pretty familiar if you've ever used a web map before. "Map key" in the blue box half way down on the left side has the legend (road types, colors, etc.). Search will find a place by name or address. Detailed instructions on how to use it, how to contribute, and so on can be found on the project's wiki: <http://wiki.openstreetmap.org/>. There are all sorts of extensions, add-ons, mashups, third-party interfaces, and so on to OSM. You want something that gives you topographical maps with bicycle routes == Easy contributions == You don't need to have a GPS, know anything about maps, or install software to contribute to OSM. The OpenStreetBugs site <http://openstreetbugs.appspot.com/> lets you add tags denoting errors or omissions. Want to add a note about that great burrito place down the street? You can, with just a browser and a few mouse clicks. One neat thing Richard showed us was a mashup using overhead imagery generously made available to the project by Yahoo. While OSM cannot use that aerial imagery in their database, it is acceptable to overlay it on the OSM map. You can use that to help check and/or correlate Free OSM data. == Surveying == Of course, most of the really good map data comes from volunteers contributing GPS-based surveys. But Richard explained how anyone can contribute detailed survey data with fairly unremarkable, off-the-shelf, consumer-class equipment. All you really need is a GPS receiver that can record GPS tracks. A track is essentially just a series of GPS coordinates with timestamps, showing where you were at a given time. By combing a GPS track with additional data, you can know *what* was there. Some people keeps notes on paper. Some people keep notes in a computer. Some people take pictures with a digital camera. Some use a voice recorder (enabling the option of a "stream of consciousness"). In all cases, the only thing you need is for each entry to have a timestamp. For written notes, you'll need to look at your watch and write it down. Most other techniques have facilities for time: Pictures record it in the EXIF data, audio has a time counter, etc. To correlate the two data streams, you record one point at the start against the clock in the GPS tracker. Perhaps the simplest example would be using the digital camera to take a picture of the clock display on the GPS. Then it's just a simple matter of taking the GPS track, feeding it into an appropriate program, and transcribing your notes. Transcribing might mean looking at pictures or listening to audio, and where you see/hear "corner of 5th Street and Maple Ave", you tell the software that at that GPS track point, 5th Street and Maple intersect. The software automates most of the work of correlating and annotating -- or so Richard says. :) == Fancy software == If you want to do actual, direct map editing (as opposed to the tagging that OpenStreetBugs does), you'll need something slightly more sophisticated than a web page: You'll need a web page with Flash. "Potlatch" is a Flash-based OSM editor. If you click the "Edit" tab on the OSM main page, that's what you'll get. For even more power (or just to avoid Flash), there is JOSM, which is a Java-based OSM editor. It runs stand-alone, outside the browser. == Community == As with most "open source" sort of projects, there's a social/community aspect to it. There are projects (details on their wiki) and local user groups. There are regular "mapping parties" all over the planet. A bunch of people get together with some GPSes and some paper maps, maybe some laptops or OSM prints, and figure out how they want to improve things. They make some GPS traces, then meet back together, and go over what they have. Enjoying good food or drink is optional, but typical. The project started in the UK, and has been popular in other parts of the world. Perhaps because there have been low-cost proprietary mapping solutions available in the US, OSM has had less established interest here. However, it's starting to take off. You could be instrumental in your community! http://wiki.openstreetmap.org/index.php/WikiProject_United_States == More information == http://www.openstreetmap.org/ http://wiki.openstreetmap.org/index.php/Main_Page http://www.gnhlug.org/presentations/2008/09/2008-09-18_IntroToOSM-Nashua.odp -- Ben _______________________________________________ gnhlug-discuss mailing list email@example.com http://mail.gnhlug.org/mailman/listinfo/gnhlug-discuss/