2012/5/23 Martin Koppenhoefer <dieterdre...@gmail.com>: > 2012/5/23 Martin Vonwald <imagic....@gmail.com>: >> Let's have a look at a street around here: it has two general lanes, >> one cycle lane and two side walks. I should map this with: >> * one way is "main" way >> * two ways for the lanes >> * one way for the cycle lane >> * two ways for the side walk >> * one relation >> So this gives me seven ways and one relation just for one street. > First of all: it is not "just for one street", it is 5 "lanes".
It still is "just one street" - with five "lanes" ;-) > Suggestion (for the same street), high level of detail (i.e. I would > use this only for special cases, not for the average road without > irregularities): > .... > So I end up with 4 ways (highway, 2 sidewalks, cyclelane), one > relation (area) and some nodes (lowered kerbs). Of course this is more > complex, but you also get a whole lot more of detail, I see it the other way around: the increase in complexity does not justify the increase in detail. > especially if > there is more stuff to take into account (geometry not perfectly > parallel, barriers which are (partially) between the sidewalk and the > road, ability to map barriers on the sidewalk only, etc. If one would allow to change the width of the xway-parts, you could map geometry that is not perfectly parallel. > You will not map every street with this detail I guess, but you could > do it for situations that are complex in the real world. See - that's the main problem of this approach. It is much too complex for the common situations, so we should only use it in complex situations. And this will lead to a continuous switch between this approach and "standard" mapping. Imagine that: every now and then a simple road, specified by one way with some tags, magically changes to four, five, (how many was it) ways and a relation and just a few meters further collapses back to a single way. Do you think, that this is understandable? Maintainable? A solution that doesn't cover both - simple and complex - will fail IMO. Another possibility would be a solution, that seamless extends the simple case to the complex. The area-relation is missing this "seamlessness". > Doing it with > tags instead of dedicated geometry would in most (complex) cases > result in much less readable map data than explicit geometry (IMHO). I agree on this. I just question this particular geometry approach. >> If I >> want to move the "street" I have to move seven ways. > why would you want to move a street that you have surveyed up to this > level of detail? I think this is hypothetical (and btw: it is 6 in > your example). Japan moved a few meters not so long ago. >> If I want to add >> a junction I have to add a node to every way. > Yes, (see above, really not likely that you map a street with 5 ways > in every detail and then you discover that you "forgot" a whole > junction). I didn't forget the junction - it was just built. Facts changes! > Of course the junction will be more complex to map compared > to a simple node, but this is also one of the reasons you are doing > it: to get more details how the junction looks like. >> If the connecting road >> is also represented by seven ways I would have to connect... no, I >> don't count now... a lot of ways. > actually you would have to connect only those ways that are > intersecting in reality, not all of them (see above). I know, but this is still "a lot" compared to "one". >> Now I want to add a route relation for a bicycle route. For this I >> have to split the "street". > not at all, you will have the cyclelane where you put the relation to > and you will _not_ have to split the street. Then I misunderstood the proposal. That would be good. >> I have to split all seven ways, even if >> the bicycle route only refers to the bicycle lane. Excuse me, I'll >> stop right here. > I don't understand you here, can you explain this? Same as above. I erroneously assumed a statement which is valid for steps should also apply to other areas. >> BTW: >>> you will not get the support of who is interested >>> in the details of shape. >> If one would allow to change the width of each part at each node of >> the xway, you could quite nicely cover the shape of many features. > how would you know how to interpolate between two widths? It could be > a sharp corner or a smooth change. (almost) every corner at every > intersection is rounded. Will we split every x-way in y parts at any > of these points? Won't it be very difficult to get the center and > widths right in the case that the change of width is all on one side > of the street surface while the other keeps going straight? (This is > almost always the case btw.). The way I think about it, it would be quite simple: just draw the ways/lanes/barriers/whatever as they are, but they magically glue together and the width of each part is automatically determined. Don't ask me about details! I figured this out just a few hours ago. > Cheers, > Martin Same, Also ;-) _______________________________________________ Tagging mailing list Tagging@openstreetmap.org http://lists.openstreetmap.org/listinfo/tagging
