openstreetmapoverpass-api
I've already knew that I can find all intersections on map by
Code.
My question is that I've knew one intersection and how I can get the information like lat and lon on others connecting intersections .
I've already get lat and lon of intersection A .
How to get the information on others connecting intersections in the following picture?
(I edited my answer for your follow-up questions)
You have to use the order in which the node IDs are referenced by the corresponding <way> element in the XML file. In contrast, the order in which the <nodes> elements appear in the XML file is completely irrelevant.
Furthermore, as you already discovered, a relation can contain multiple separate ways forming a single polygon. Here, the relation doesn't necessarily has to reference the ways in the correct order. Consequently the correct order of the ways has to be determined by looking at the first and last node of the way. Consecutive ways will share the same last and first node.
For a neat sorting algorithm you can take a look at the source code of JOSM.
Alternatively you might take a look at overpass turbo which provides a GeoJSON output which Leaflet should be able to handle.
I would recommend the following approach: it returns coordinates for ways' nodes 'in place', like you described in your question.
The only thing, which is missing in the output is the technical OSM node-id (ref). I assume that for use case of drawing some boundary area on a map, this is most likely not needed. If you take a look at the screenshot below, overpass turbo is drawing all postal code areas on the map without any issue.
area(3600062649);
rel(area)["boundary"="postal_code"];
out geom;
http://overpass-turbo.eu/s/7In
Example output:
<relation id="1301656">
<bounds minlat="51.3145882" minlon="12.2366519" maxlat="51.3391521" maxlon="12.3034696"/>
<member type="way" ref="87537618" role="outer">
<nd lat="51.3179538" lon="12.2426125"/>
<nd lat="51.3178723" lon="12.2414464"/>
<nd lat="51.3176008" lon="12.2399198"/>
[...]
</member>
[...]
<tag k="boundary" v="postal_code"/>
<tag k="note" v="04205 Leipzig"/>
<tag k="postal_code" v="04205"/>
<tag k="postal_code_level" v="8"/>
<tag k="type" v="boundary"/>
</relation>
Best Answer
This is not possible with your current query since it only returns nodes. To determine other connected intersections you will need nodes and ways.
Downloading ways with the highway key and all of their nodes can be done with a really simple query:
See the example at overpass turbo.
Afterwards you have to compute a routing graph. There is a step-by-step explanation for building a routing graph from OSM data. For a general overview take a look at routing in the OSM wiki.