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    Re: An essay about maps
    From: Frank Reed
    Date: 2010 Nov 14, 17:34 -0800

    Peter, you wrote:
    "Incidentally, while the Google map shows lakes everywhere - almost looks like a map of Finland - they are usually bone dry. "

    That's one nice thing about Google Maps. You can switch to the "satellite view" (frequently actually aerial photography) and see that those lakes are normally dry. Sometimes different scales of aerial imagery are taken under radically different conditions. If you visit some of the intermittent lakes in California, at one scale the lake is bone dry and at a closer scale it's overflowing with water. It's rather bad cartography, on the part of the Google Maps designers, that they don't more clearly indicate intermittent water bodies (e.g. with hatched lines or a very little blue, both of which are common for this purpose).

    The mapping of this area including Hungerford itself is really bad. If you go to this small town, you'll find that the local "street map" doesn't align with the roads visible in the "satellite view". For example, the mapped version of Centauri Street runs through the middle of a building. Arcturus, Canopus, and Aldebaran streets barely exist at all in the satellite view (I figure I get ten points for noticing that some of the local streets are named for navigational stars). Even the major road in the area, labeled "Hungerford Road" is clearly mismapped as it passes through town and then continues north. The intersection with Aldebaran Street, as drawn is clearly the middle of nowhere --no street, no intersection. The "mapped" version of the town looks like an original plan for the settlement rather than an actual map.

    Maps can't be "100% accurate" (what in the world would that mean?) and you can't pass a law to achieve anything along those lines. The author of the article is thinking a little "left" of center here. But surely Australians shouldn't be happy with such awful maps. This "map" of Hungerford is no better than a general impression. What's the fix here?

    The crowd or wiki or social network solution to mapping is fair, but unfortunately it suffers from serious bias. Even Google Maps lets users move markers around and they frequently do --for laughs. Until you get enough users who take an ownership interest in a region, you can get real nonsense. This phenomenon is common enough in minor Wikipedia articles. Would there ever be enough people interested in a place like Hungerford to maintain its map, as volunteers, and fight the entropy of wiki vandalism?

    For such sparsely populated regions, software analysis may yield better results at least for defining the network of trails and roads, especially in areas like central Australia where trees don't usually block the view. If a linear feature has a certain width and connects other points on a network of linear features, then it has a good chance of being a road or trail. But that's not much of a map. We need names on those roads and trails, if they have names, and we also need a hierarchy. Local governments can often provide road names. To some extent the imagery can provide the hierarchy. Multi-lane highways are at the top. Dirt roads are lower down the hierarchy, one lane dirt roads that cross streams further down still. Even in densely populated areas, the hierarchy can sometimes be the biggest flaw in the system. For example, in the US, most mapping products automatically place the Interstate highways at the top of the heap. All state roads are lower down. When they then solve for optimized routes, they will bypass state highways even if they're excellent. I noticed this especially in Texas where roads that look secondary on the maps often turned out to be as good as any of the Interstates. This is a case where a software analysis would definitely yield better results. Another software solution, available to Google specifically since they have fleets of nosy Google-cam vans, is to read the road signs using software. Speed limits, stop signs, and (very useful) "one way" signs can be read and incorporated into the maps and the routing solutions.

    As far as supporting the results, product reviews are probably the best solution. Publishers who produce mediocre maps should get called out on it, and publishers who produce good maps could perhaps get a "NavList Seal of Approval". Well, ok, not us, but some organization with an interest and a reputation could reward the publishers of better maps, both digital and paper.

    By the way, does the U.K. Ordnance Survey have a monopoly on the original government-created data? I assume that it was privatized with the consideration that it would have a monopoly. Hence its commercial success is probably a bit of an illusion, right?

    -FER


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