问题
I'm trying to get speed limit from Here API maps but I can't find the way to do it. I tryed few example on web site but the only one that works is the one which require point of start and point of stop of the route.
I would like to get the speed limit given only one point ( or a box ). Which api do I have to use? Is there an example?
https://route.cit.api.here.com/routing/7.2/calculateroute.json?jsonAttributes=1&waypoint0=51.31854,9.51183&waypoint1=50.11208,8.68342&departure=2019-01-18T10:33:00&routeattributes=sh,lg&legattributes=li&linkattributes=nl,fc&mode=fastest;car;traffic:enabled&app_code=appcode&app_id=appid
This is the waypoint one but is not what I'm looking for, I would like to pass it only a Latitude / Longitude.
Thank you
回答1:
You can achieve this by using PDE API(Platform Data Extension)
- You have to first map your geocordinates(lat,long) to a navigable position(lat,long) for the given coord and the Functional Class(FC1-5) it is located in. This you can achieve by a simple geocoder request
- You can calculate tilexy values based on the navigable lat,long and pass it to PDE API for querying speed limit layer on that particular FC class.
Look at https://tcs.ext.here.com/examples/v3/link_speed_locator example which covers this exact usecase.
Below is a sample geocoder request. Here prox parameter is your lat,long
https://reverse.geocoder.cit.api.here.com/6.2/reversegeocode.json?app_id=xxxx&app_code=yyyy&prox=50.133848, 8.715332,500&mode=retrieveAddresses&maxResults=1&additionaldata=SuppressStreetType,Unnamed&locationattributes=linkInfo
Below is a sample pde request
https://pde.cit.api.here.com/1/tiles.json?layers=SPEED_LIMITS_VAR_FC1,SPEED_LIMITS_VAR_FC2,SPEED_LIMITS_VAR_FC3,SPEED_LIMITS_VAR_FC4,SPEED_LIMITS_VAR_FC5,ROAD_GEOM_FC1,ROAD_GEOM_FC2,ROAD_GEOM_FC3,ROAD_GEOM_FC4,ROAD_GEOM_FC5&levels=9,10,11,12,13,9,10,11,12,13&tilexy=536,398,1073,797,2147,1594,4294,3188,8588,6377,536,398,1073,797,2147,1594,4294,3188,8588,6377&app_id=xxxx&app_code=yyyy
Read more about it in the developer site - https://developer.here.com/documentation/platform-data/topics/quick-start-view-map-data.html
Hope you find this useful!
回答2:
The ReverseGeocoder has rarely used mode "trackPosition" (mode=trackPosition).
In combination with locationattributes=linkInfo you may retrieve the speed limit for that matching road.
来源：https://stackoverflow.com/questions/55412834/how-to-retreive-speed-limit-from-here-maps-given-a-latitude-and-longitude