GOOGLE Maps and Yahoo Local Maps are great for finding US-based locations, but if you?re trying to find your way around Metro Manila, they aren?t very useful. Data is so sparse, in fact, that street-level maps on these sites?if they exist at all?are practically useless.

Long frustrated by the paucity of local maps, I was intrigued when reader Jim Morgan told me about what he says is the most complete online map of Manila.

?I?ve been cotributing to a project called OpenStreetMap (www.openstreetmap.com). Over the past year, we?ve pretty much nailed Manila, and it?s without doubt the most complete online map of Manila,? writes Jim, who founded the Hong Kong-based information security company Datalude.

Exploring OpenStreetMap, I found that its local map is indeed far better than anything else that?s available. On the other hand, that bar has been set pretty low, given that Google Maps only displays the city?s main thoroughfares, and Yahoo Local Maps doesn?t even provide street-level information for the Philippines.

So how does OpenStreetMap fare?

First the good news: some areas of Metro Manila, such as the commercial district in Makati, are very detailed and the maps are uncluttered and easy to follow.

Second, the maps and the Global Positioning System (GPS) data are free to use?in print, in blogs, your phone or just about anywhere?as long as you respect the terms of the Creative Commons license, which are: 1) Anyone can copy the data; 2) If you incorporate it into something else, that product must also be copiable under the same terms and conditions; and 3) When you copy it, you give credit to the copyright owner.

This approach is a major departure from most street maps, which are covered by commercial licenses that forbid their reproduction without the express consent of the copyright owner. In practical terms, this means you can?t simply take a map off Google Maps and use it on your blog because the copyrights owned by the mapping companies legally bar you from doing so.

Third, if you don?t like what you see, you can help improve it. OpenStreetMap is like a Wikipedia for maps, encouraging users to contribute to it, as long as they don?t copy or trace from commercial maps.

?Contributors to OpenStreetMap take handheld GPS devices with them on journeys, or go out especially to record GPS tracks. They record street names, village names and other features using notebooks, digital cameras, and voice-recorders,? the OpenStreetMap Web site explains.

?Back at the computer, contributors upload those GPS logs showing where they travelled, and trace out the roads on OpenStreetMap?s collaborative database. Using their notes, contributors add the street names, information such as the type of road or path, and the connections between roads... That data is then processed to produce detailed street-level maps, which can be published freely on sites such as Wikipedia, used to create handheld or in-car navigation devices, or printed and copied without restriction. ?

Of course, like Wikipedia, OpenStreetMap is vulnerable to errors introduced by its contributors, but its organizers believe these mistakes will be eventually weeded out.

?The essence of a wiki-style process is that all users have a stake in having accurate data,? the Web site says. ?If one person puts in inaccurate data, maliciously or accidentally, the other 99.9 percernt of people can check it, fix it, or get rid of it. The vast majority of good-intentioned participants can automatically correct for the few bad apples.?

A few problems I encountered:

The search seemed slow and sometimes became totally unresponsive.

Editing, while not too difficult to figure out, isn?t all that easy to do, either. Street names do not appear in the edit window and you have to click on a street to find out what it is. There didn?t seem to be an easy way to scroll the map in edit mode.

Finally, while I am loathe to do so, I must disagree with Jim on one point: nobody has nailed Manila just yet. I can understand if the small street in Sta. Cruz, Manila, where I grew up doesn?t show up on the map, but there?s still a lot of work to be done when Ongpin Street?the very heart of Chinatown?isn?t labeled on the map. But of course, part of the fun in a project like OpenStreetMap is that you can be part of the process, improve the content?and put yourself on the map.

Column archives and blog at: http://www.chinwong.com