On Fri, Mar 14, 2014 at 03:55:39PM -0300, Fernando Trebien wrote: > I don't think you should be required to check the river's layer tag. > Validators should do this job for you, it's quite easy to write a rule > for that.
validators can check for many errors but if you want to change anything you have to understand the whole situation. Imagine you want to add a new bridge to a complex freeway intersection with junctions and overpasses.. the validator will only prevent the most obvious errors but will give you no clue how to fix them correctly. > Given two ways that cross internally (excluding connections at > endpoints), and considering the "layer value" defined explicitly in a > tag or implicitly 0 when the tag is missing, have the validator issue > a warning in the following situations: there is no difference between connections in endpoints or in a crossing point as far as I can tell. > 1. The ways have the same layer value and are unconnected. (They > should be connected, or else something is surely missing. This could > actually be considered an "error".) except for aerial ways and similar exceptions > 1.1. Also warn if if one way is a waterway and the other is a highway > and the connection is not explicitly a ford. (It should be, for > clarity. If it's not, it's also possibly not a ford, therefore the > connection is wrong.) there is also the odd case of highways across dams, those are connected with the waterway > 2. The ways have different layer values and both are missing a tunnel > or a bridge tag. (One of them must be either a bridge or a tunnel. > They can both be tunnels or bridges, but they can't be "none of those > two" simultaneously in the real world.) or one of covered,location,indoor,steps,lift or level, maybe more. > 2.1. Additionally, if one of them is a bridge and the other is a > tunnel or is neither a tunnel nor a bridge: the bridge should have a > greater layer value. > 2.2. Similarly, if one is a tunnel, its layer value should be lower if > the other is a bridge or has neither tag. except for indoor mapping and maybe other weird cases. > These rules apply to any arbitrary combination of stacked waterways > and highways that I can think of right now. also railways? > A few examples using two > overlapping ways: > > a. The ways are connected and do not have a layer tag: everything is > ok, no rules issue a warning. > b. The ways are not connected and do not have a layer tag: rule 1 > issues a warning. They must either be connected or lie at different > layer levels. > c. The ways are not connected, both have the same layer (say layer=3 > or layer=-4), and have no other tags: rule 1 issues a warning. Similar > to situation "b". > d. The ways are not connected and one of them has a layer=-1 tag and > no other tags: rule 2 issues a warning. more general: not connected, different layer values and not one of bridge,tunnel,covered,location,indoor,steps,lift, no level tag and a few more things to take into account. I am not sure it is so easy to catch all that. > e. The ways are not connected and one of them has a layer=1 tag and no > other tags: rule 2 issues a warning too. identical to d? > f. The ways are not connected, one of them is a bridge with layer=2 > and the other is a tunnel with layer=5: rule 2.1 issues a warning. unless indoor or other strange cases > g. The ways are not connected, one of them is a tunnel with layer=1 > and the other is neither a bridge nor has a layer tag (layer=0 is > assumed): rule 2.2 issues a warning. > Actually, situation "d" is what would discourage people from using > layer=-1 to work around today's validator warnings. With this ruleset, > it's impossible to eliminate the warning without actually taking > action on bridges. It is a lot easier saying that every bridge and tunnel must have a layer tag and enforce that than catching all the situations mentioned in situation "d". With some luck, you can restrict "d" to waterways and it becomes "easy" Richard _______________________________________________ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
