pe, 2008-05-02 kello 11:07 +0100, Dave Stubbs kirjoitti:
> The main problem with this kind of idea is it's complete subjectivity. > The bike_suitability style of tag is less of a problem because there's > a fairly clear reference point: ie: would you be happy cycling a road > bike down this path, or would the path break it (or you)? So while > subjective, people will generally be working from a similar baseline. > But when you start applying -2..+2 grading, you need to calibrate > everyone's expectations of what that actually means somehow. How do I > know this is a +2 instead of a +1? Inevitably what this entails is > writing some kind of guide where you detail all the things you should > look at to determine the score. By the time you've done this you've > probably come up with a reasonable surface tagging scheme you could > have actually used in the first place :-) > It might be something you could then apply to a map rendering to > indicate how good a route is without providing the fine detail. I see that I left out from my idea the essential part that grading would be used only in addition to tags for track type and surface material, and only in those cases, when regular tagging, while properly done, would give a wrong picture of the reality "in the field". I understand the problem with subjectivity, and of course, if people come up with a regular tagging scheme that is "objective" and works, then there would be no need for grading. I could imagine, though, that if this objective tagging scheme fails to give people the tools they need to describe the situation in the field, the scheme would be often bent to fit the reality, and this way, in effect, being also used as a grading tool. I think bike_suitability would bring new levels of subjectivity to the mix. At least in my country some half of the bicycles in use are neither road bikes, hybrids or mountain bikes. There's no clear category these other bikes belong to, and for example their tyre diameter varies greatly - an important aspect affecting driveability. You would need either more categories (they would be fuzzy), or artificially squeeze the rest of the bikes to existing categories (fuzzy and subjective). Also, how comfortable the imagined driver would feel riding a certain type of bike on the track in question? What kind of driver - an 18 years old? 30? 50? Fit or not-so-fit? Experienced biker or not? A young, fit driver might feel OK to ride on most tracks with anything except a road bike. Some one else might feel very differently. So, bike_suitability seems to me to be even more subjective than surface grading. Categorizing tracks for bike types partly works, but is to large part arbitrary. When doing so, you can't avoid categorizing drivers (whether or not you do it knowingly), which is very subjective - even more so than grading a track surface. Anyway, it seems to me that what ever is going to be done, there's going to be subjectivity involved :-) Regards, Ari Torhamo _______________________________________________ talk mailing list [email protected] http://lists.openstreetmap.org/cgi-bin/mailman/listinfo/talk
