Re: [Tagging] RFC Bag shop
On Tue, Oct 28, 2014 at 10:21:51AM +1100, Warin wrote: But English is not 'clean'. So I would say (in speach) 'a shop for motorcycles' .. but 'a motorcyle shop' so plural then singular. Or'a shop for alcohol' .. but 'an alcohol shop' so singular in both cases. Or 'a shop for shoes' .. but 'a shoe shop' so againplural then singular. IIRC in some textbook I read that in a shoe shop, shoe is not singular, it isn't plural (to say nothing of the Saxon genitive), it's the stem; I'm not sure they were right, though. ___ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
Re: [Tagging] natural=bay as nodes are evil
On Tuesday 28 October 2014, Janko Mihelić wrote: If you want to formulate a formal mathematical rule for where the node for a bay is best placed: Place it so the variance of the distance of the node to the bay's shores is minimized. Most existing nodes comply with this rule remarkably well. What's the best place for the node in Guantanamo Bay? Is the current node well placed? I'd say it is. Note the algorithm i sketched in its simple form would seriously underestimate the bay size due to the peninsula in the middle - same problem as small islands in the bay which i already mentioned. It is fairly easy though to detect and fix this (by making use of the fact that a bay is 'mostly surrounded by land'). On a general note the established tagging conventions are of course not well suited for tropical coastal landforms dominated by mangrove. Technically you might also consider the inner bay a lagoon rather than a bay. -- Christoph Hormann http://www.imagico.de/ ___ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
Re: [Tagging] what does maxheight=none mean?
2014-10-27 20:21 GMT+01:00 Friedrich Volkmann b...@volki.at: But when we see nothing, it's plain wrong to add something to the database. E.g. when there's no building, you wouldn't draw an area and tag it building=no. For the same reason, you shouldn't make up a maxheight=none (or unsigned) when there's no sign. It's not about seeing nothing, it is about verifying that the default maxheight applies, i.e. there is no specific maxheight sign. This is really different from nothing and might be better than no information at all (which can mean imcomplete mapping or no maxheight sign). cheers, Martin ___ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
Re: [Tagging] natural=bay as nodes are evil
On Mon, Oct 27, 2014 at 04:28:53PM -0400, Eric Kidd wrote: But the key point here is that none of these official sources represent bays as polygons. GNIS uses a pointssomewhere in the bay. The nautical charts print the name somewhere in the middle of the bay. Effectively, the official data really is a point, plus whatever guesswork a human reader supplies. +1 Also, I am reading the arguments about estimating bay area so I am curious - when was the last time someone asked about bay area in square kilometers? I think it makes only sense in the context of territorial waters, fishing or mining rights etc. In such cases there will be an officially supplied boundary that can be used but will not necessarily agree with traditional extent of the bay. Richard ___ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
Re: [Tagging] natural=bay as nodes are evil
2014-10-28 10:57 GMT+01:00 Richard Z. ricoz@gmail.com: Also, I am reading the arguments about estimating bay area so I am curious - when was the last time someone asked about bay area in square kilometers? I think it makes only sense in the context of territorial waters, fishing or mining rights etc. The assumption is that a large bay will typically be more important than a smaller bay. For a good rendering you'd show only the more important bay names in medium zoom level and show the less important ones in higher zoom levels. You would use the size to decide which name to omit in case you'd not have space to render all of them. Territorial waters are at most loosely connected to bays, because you don't use the coastline to determine them, you use the baseline. Cheers, Martin ___ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
Re: [Tagging] natural=bay as nodes are evil
On Tue, Oct 28, 2014 at 11:18:43AM +0100, Martin Koppenhoefer wrote: 2014-10-28 10:57 GMT+01:00 Richard Z. ricoz@gmail.com: Also, I am reading the arguments about estimating bay area so I am curious - when was the last time someone asked about bay area in square kilometers? I think it makes only sense in the context of territorial waters, fishing or mining rights etc. The assumption is that a large bay will typically be more important than a smaller bay. For a good rendering you'd show only the more important bay names in medium zoom level and show the less important ones in higher zoom levels. You would use the size to decide which name to omit in case you'd not have space to render all of them. so to decide which label should be bigger or rendered at lower zoom level you would suggest to: * map bays as areas, with all previously mentioned issues * design a sophisticated computer algorithm to calculate the size of bays and derive bay importance from this Wow.. masterpiece of mapping for the renderer I would say. There must be easier ways of achieving this. Richard ___ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
Re: [Tagging] natural=bay as nodes are evil
On Tue, 28 Oct 2014, Christoph Hormann wrote: On Tuesday 28 October 2014, Janko Mihelić wrote: If you want to formulate a formal mathematical rule for where the node for a bay is best placed: Place it so the variance of the distance of the node to the bay's shores is minimized. Most existing nodes comply with this rule remarkably well. What's the best place for the node in Guantanamo Bay? Is the current node well placed? I'd say it is. Note the algorithm i sketched in its simple form would seriously underestimate the bay size due to the peninsula in the middle - same problem as small islands in the bay which i already mentioned. It is fairly easy though to detect and fix this (by making use of the fact that a bay is 'mostly surrounded by land'). I see. This underestimation in the peninsula case was why I though you'd want the nodes at the entry point and thus my earlier comment about natural=bay_entry. But are all bays 'mostly surrounded by land' or do some bays also have very wide entrypoints (in addition to two pockets to trigger this peninsula case)? And yes, I know it can always be solved by drawing area manually if the algorithm won't get it right. Btw, instead of huge and fragile areas we could just create a relation which holds the coastline nodes of the bay extreme end points. Although also that would probably be just as fuzzy as the outer edge would be (i.e., where the bay really would end along the coastline). -- i.___ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
Re: [Tagging] natural=bay as nodes are evil
On 27/10/2014, Christoph Hormann chris_horm...@gmx.de wrote: Since for label rendering you don't really need a polygon there is little point in actually generating it in the first place. But i have implemented and used techniques not unlike the algorithm described for rendering bay and strait labels, like in http://maps.imagico.de/#map=3/80.707/55.862lang=enl=darkr=fjui=0 That's actually a very nice rendering. The channels in particular seem to be oriented very naturally. But when I look at the underlying osm data (nodes), it is much less clear how those features are oriented. I feel like the rendering tricked me into thinking that's it, the channel is laid out this way when the actual data says nothing of the sort. To render a pretty picture, I'd certainly use something like that. To implement geofencing, area calculations, etc, I'd much rather trust a human-estimated area. The funny thing is the first thing i do for this is reduce all features mapped as polygons to a node since the polygon is useless, its outer limit is arbitrary and the sides defined by the coastline do not match the generalized coastline used to render the map. I admit I don't fully understand how your algorythm works. I can't imagine how you reduce everything to nodes and still retain information about orientation and curves. Can you change your rendering to display the infered polygons instead of the name ? ___ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
Re: [Tagging] natural=bay as nodes are evil
On 28/10/2014, Richard Z. ricoz@gmail.com wrote: On Tue, Oct 28, 2014 at 11:18:43AM +0100, Martin Koppenhoefer wrote: 2014-10-28 10:57 GMT+01:00 Richard Z. ricoz@gmail.com: The assumption is that a large bay will typically be more important than a smaller bay. For a good rendering you'd show only the more important bay names in medium zoom level and show the less important ones in higher zoom levels. You would use the size to decide which name to omit in case you'd not have space to render all of them. so to decide which label should be bigger or rendered at lower zoom level you would suggest to: * map bays as areas, with all previously mentioned issues The issues are real, but we disagree on how big they are. I'm of the opinion that they aren't worth fussing over, but YMMV. * design a sophisticated computer algorithm to calculate the size of bays and derive bay importance from this Finding the size of an area is actually much simpler than your proposed algorythm. It's implemented in stock PostGIS. It doesn't involve tuning or heuristics. It's aready used in many places in the default osm rendering (osm-carto). It is done at import time and is free from the map designer's POV. ___ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
Re: [Tagging] natural=bay as nodes are evil
On Tuesday 28 October 2014, Ilpo Järvinen wrote: But are all bays 'mostly surrounded by land' or do some bays also have very wide entrypoints (in addition to two pockets to trigger this peninsula case)? And yes, I know it can always be solved by drawing area manually if the algorithm won't get it right. The wiki defines bays as Area of water mostly surrounded by land. There are quite a few cases tagged this way with only a slight dent in an otherwise flat coastline where - if you'd map them as an area - less than half of the area outline would be formed by coastline. -- Christoph Hormann http://www.imagico.de/ ___ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
Re: [Tagging] natural=bay as nodes are evil
On Tuesday 28 October 2014, moltonel 3x Combo wrote: That's actually a very nice rendering. The channels in particular seem to be oriented very naturally. But when I look at the underlying osm data (nodes), it is much less clear how those features are oriented. I feel like the rendering tricked me into thinking that's it, the channel is laid out this way when the actual data says nothing of the sort. For a channel between two islands with simple convex shape the situation is actually much clearer than for a bay - it is a one-dimensional feature, it has a width but no length so mapping it as an area is plainly wrong. In more complicated situations the established method is to use a way connecting a few key points - up to extreme cases like here: http://www.openstreetmap.org/way/163242449 I admit I don't fully understand how your algorythm works. I can't imagine how you reduce everything to nodes and still retain information about orientation and curves. Can you change your rendering to display the infered polygons instead of the name ? I do not infer any areas, i just generate curves (splines) based on the nodes and the surrounding coastlines and place the text along them. The main problem is that spatial database systems are not well suited for this kind of work (i.e. tasks like 'find the closest coastline in a certain direction'). -- Christoph Hormann http://www.imagico.de/ ___ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
Re: [Tagging] natural=bay as nodes are evil
On 26.10.2014 17:12, Mateusz Konieczny wrote: Please, try mapping bays as areas - not as nodes. but if you - for whatever reason ever - can't map it as area then it's better to map it as node instead not mapping it at all... Just an example: I did it some times ago with something (can't remember what ist was, at least not a bay but maybe an amenity). And IIRC it was simply due to missing time at this edit. To be honest: I returned to work on this region some weeks later and changed the node to an area. So of course an area is usually better than a node. Just my 2 cents, Michael. ___ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
