I’m a newbye trying to map my hiking and bycicle gps tracks with JOSM.
Mine is a very basilar question, but I didn’t find answers, neither in this forum nor googling it…
Speaking generally, a route can have one segment used two (or more?) times, maybe in opposite directions: could I handle this?
Trying to put a second time the same segment in the window relation, I got a message warning, but I can still add it: no way however to change direction…
Obviously for navigator-functions, but also to calculate the length of the route, it’s necessary to put two times the same segment…
Direction of the way is irrelevant. Do not create routes of your personal hiking and biking trips in OSM. Only add routes that are marked in the field. Marked tracks and trails rarely use a section twice.
yes I’m a newbye but not fool
I’m learning locally (on my PC) with Josm, not thinking to upload my. osm data, and I’m interested in developing applications for .osm data, not to update them.
Planning to develop navigator apps, which calculate the route connection for several points (traveling salesman problem) :
Technically there is nothing which tells in which direction a relation uses a way. So when you define how you use the datatype relation you must specify for yourself how this is stored. For example you could do it like in PT-Routes by the order of the elements, or like in hiking routes by setting the role to i.e. “forward” or “backward”.
In the example of PT-Routes the direction is calculated by starting at the first way, checking which of it’s endnodes is an endnode at the following way, and you know the direction of both. Then take the other endnode of the second way and compare it to the third way’s endnodes to find it’s direction, and so on.
Thank you rayquaza for your comment, I’ll try to use the forward/backward roles (I suppose that forward/backard is related to the way direction, that is implied by the nodes’ order).
Sure, like for gpx tracks, I assume that the ways’ order fixes the start/end points.
I’m starting to develop (using the R language) a tool which elaborates OSM routes (relations), computing distances and elevation profiles: so it’s mandatory that all the ways are connected and ordered;
about this I find very useful that in the relation window we can use the up/down buttons (to change ways’ order) and the right-icons to check if the ways are connected.
Thank you Joost for your information, I didn’t know that site, it’s nice!
However, I decided to develop this tool because I was frustrated that everywhere I found only elevation data brought from SRTM: it’s a good model because it covers all the planet, but its resolution is 30 meters, it’s not enough for mountain places.
The only other source I know is from Google, but their aren’t public data, license constraints are heavy: The Elevation API may only be used in conjunction with displaying results on a Google map; using elevation data without displaying a map for which elevation data was requested is prohibited.
So I’m working to elaborate other DEMs (digital elevation models) : local authorities (at least in Italy) maintain public data for digital elevation, and their resolution is 10 meters (sometimes 5).