2010/12/19 Steve Bennett <[email protected]>: > On Sun, Dec 19, 2010 at 11:04 PM, M∡rtin Koppenhoefer > <[email protected]> wrote: >> This discussion is simply about the quality level: are you satisfied >> with probable information derived from an aerial photo depicting the >> situation some years ago, or do you want to insert only information >> you verified on the ground and you can guarantee for? > > Ah, cool. For me, this is a no-brainer: very comfortable with > "probable" information. I'd rather have 1000 streets at 90% accuracy > than 10 streets at 100% accuracy. Yes, that means I've created many > errors in OSM.
yes, in you example you would have 100 wrong streets. I'm not believing your numbers btw.: I doubt that you can only visit and map 10 streets with the effort you have to put 1000 streets from orthofotos (1%). Even if this ratio was only 10% (in my experience mapping takes as long as surveying, which would result in 50% for no survey at all) I would prefer 100 reliable streets to a thousand of which a hundred are wrong. If there is no information, this is at least reliable in the sense that you know you can't rely on it ;-) > Btw, no idea how a ground survey would give a better idea of > highway=tertiary vs residential. agreed, this requires actually not one ground survey but good knowledge of the area. Also, all suburban streets (of which > the example was clearly one) are access=yes, no question there. OK, so you do have good knowledge of the circumstances/surroundings, which is important. To explain myself: I'm not against mapping from aerial imagery, I do it myself, but there are limits. A very good map can't be done just from orthophotos. cheers, Martin _______________________________________________ talk mailing list [email protected] http://lists.openstreetmap.org/listinfo/talk
