On Monday 13 April 2015, Torstein Ingebrigtsen Bø wrote: > Hi, > > I'm currently importing topological data of Norway to OSM. From the > data set we have riverbanks; however, we do not have the deepest > middle way as required by the wiki [1]. This middle line is therefore > drawn manually. This is a time consuming (and dull) job. For one > municipal it takes around 5-10 hours to draw all these lines, in > Norway we have 428 municipals. Drawing all these middle lines will > slow down the time to import everything dramatical. I am therefore > curious of what is the benefits of this line. Is it really necessary > or is it a "nice to have"?
It is the other way round - the riverbank polygon is optional and 'nice to have'. The waterway line is what actually defines a river in OSM, it also gets the name tag and other attributes. The primary reason for this is to map the water flow structure. Also it is much easier to verify and fix structural errors in waterway line mapping than for water polygons. Generating a waterway line when you only have polygons is fairly simple via straight skeletons (http://en.wikipedia.org/wiki/Straight_skeleton) If the source data set does not contain continuous line features for rivers generating those should be part of import preparation. And i disagree with Janko here - if the source data does not contain certain information that is required according to OSM mapping conventions you should not import the data unless you produce the information in some way (either through manual mapping, computing the missing data or getting it from other sources). Otherwise the data becomes dead mass in the OSM database. -- Christoph Hormann http://www.imagico.de/ _______________________________________________ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
