OffRouteDetector throws error for line with two identical points

[karussell]

When using the latest version (main branch) of the android demo against the GraphHopper API I get an error for the last segment of the route:

org.maplibre.geojson.turf.TurfException: Turf nearestPointOnLine requires a List of Points made up of at least 2 coordinates.
 at org.maplibre.geojson.turf.TurfMisc.nearestPointOnLineInternal(TurfMisc.kt:244)
 at org.maplibre.geojson.turf.TurfMisc.nearestPointOnLine(TurfMisc.kt:228)
 at org.maplibre.geojson.turf.TurfMisc.nearestPointOnLine$default(TurfMisc.kt:221)
 at org.maplibre.navigation.core.utils.ToleranceUtils.dynamicOffRouteRadiusTolerance(ToleranceUtils.kt:30)
 at org.maplibre.navigation.core.offroute.OffRouteDetector.createOffRouteRadius(OffRouteDetector.kt:166)
 at org.maplibre.navigation.core.offroute.OffRouteDetector.checkOffRouteRadius(OffRouteDetector.kt:156)
 at org.maplibre.navigation.core.offroute.OffRouteDetector.isUserOffRoute(OffRouteDetector.kt:80)
 at org.maplibre.navigation.core.navigation.NavigationHelper.isUserOffRoute(NavigationHelper.kt:482)
 at org.maplibre.navigation.core.navigation.engine.MapLibreNavigationEngine.determineUserOffRoute(MapLibreNavigationEngine.kt:142)
 at org.maplibre.navigation.core.navigation.engine.MapLibreNavigationEngine.processLocationUpdate(MapLibreNavigationEngine.kt:100)

The problem seems to be that one of the intersections lists contains only a single element, i.e. this code creates a line with just one point.

Complete example response:

{"routes":[{"geometry":"{ebm`BkamcYpMgFbLsEvd@}QmPugA","legs":[{"steps":[{"intersections":[{"location":[13.70423,51.086958],"entry":[true],"bearings":[343],"out":0},{"location":[13.704346,51.086725],"entry":[true,false],"bearings":[163,343],"in":1,"out":0},{"location":[13.704452,51.086515],"entry":[true,false],"bearings":[163,343],"in":1,"out":0}],"driving_side":"right","geometry":"{ebm`BkamcYpMgFbLsEvd@}Q","mode":"driving","maneuver":{"bearing_after":0,"bearing_before":0,"location":[13.70423,51.086958],"modifier":"straight","type":"depart","instruction":"continue onto Leipziger Straße"},"weight":122.1,"duration":13.7,"name":"Leipziger Straße","distance":122.1,"voiceInstructions":[{"distanceAlongGeometry":80.0,"announcement":"turn left onto Jubiläumsstraße, then arrive at destination","ssmlAnnouncement":"<speak><amazon:effect name=\"drc\"><prosody rate=\"1.08\">turn left onto Jubiläumsstraße, then arrive at destination</prosody></amazon:effect></speak>"}],"bannerInstructions":[{"distanceAlongGeometry":122.1,"primary":{"text":"Jubiläumsstraße","components":[{"text":"Jubiläumsstraße","type":"text"}],"type":"turn","modifier":"left"},"secondary":null,"sub":{"text":"Arrive at destination","components":[{"text":"Arrive at destination","type":"text"}],"type":"arrive"}}]},{"intersections":[{"location":[13.704755,51.085911],"entry":[true,true,false],"bearings":[69,161,343],"in":2,"out":0}],"driving_side":"right","geometry":"md`m`BebncYmPugA","mode":"driving","maneuver":{"bearing_after":0,"bearing_before":0,"location":[13.704755,51.085911],"modifier":"left","type":"turn","instruction":"turn left onto Jubiläumsstraße"},"weight":87.0,"duration":19.6,"name":"Jubiläumsstraße","distance":87.0,"voiceInstructions":[{"distanceAlongGeometry":25.0,"announcement":"arrive at destination","ssmlAnnouncement":"<speak><amazon:effect name=\"drc\"><prosody rate=\"1.08\">arrive at destination</prosody></amazon:effect></speak>"}],"bannerInstructions":[{"distanceAlongGeometry":87.0,"primary":{"text":"Arrive at destination","components":[{"text":"Arrive at destination","type":"text"}],"type":"arrive"},"secondary":null}]},{"intersections":[{"entry":[true],"bearings":[0],"in":0,"location":[13.705918,51.08619]}],"driving_side":"right","geometry":"{u`m`B{jpcY??","mode":"driving","maneuver":{"bearing_after":0,"bearing_before":0,"location":[13.705918,51.08619],"type":"arrive","instruction":"arrive at destination"},"weight":0.0,"duration":0.0,"name":"","distance":0.0,"voiceInstructions":[],"bannerInstructions":[]}],"summary":"GraphHopper Route 0","weight":33.3,"duration":33.3,"distance":209.1}],"weight_name":"routability","weight":36.4,"duration":33.3,"distance":209.1,"voiceLocale":"en"}],"waypoints":[{"name":"","location":[13.70423,51.086958]},{"name":"","location":[13.705918,51.08619]}],"code":"Ok","uuid":"e4e518ed5ffd4ed793ea5c3a5766ef96"}

via URL https://graphhopper.com/api/1/navigate/directions/v5/gh/car/13.70421,51.086954;13.706496,51.086818?geometries=polyline6&steps=true&roundabout_exits=true&voice_instructions=true&banner_instructions=true&access_token=pk.<API_KEY>

[karussell]

It was fixed in f35885e. See this line.

I.e. only the dependency needs to be (released and) updated?

[boldtrn]

Thanks for looking into this.

I.e. only the dependency needs to be (released and) updated?

Can you clarify what you mean? There is a 5.0.0-pre2 that should contain this change?

[karussell]

Unfortunately I do not know in detail how the dep management works in detail with gradle/kts.

I used the main branch (+fresh clone if the repo) and still the demo did not pick up the latest dependency. But maybe I did some mistake elsewhere.

[boldtrn]

If you build this in Android Studio, always make sure that you Sync (the elephant icon with the arrow in the top right) - and make sure you have the latest version of Android Studio. Usually the demo should use the local dependency. No idea what might be wrong otherwise.

[karussell]

Which example app is the one user should start app or sample?

• "app" -> example (https://github.com/maplibre/maplibre-navigation-android/tree/main/app)
• "sample" (https://github.com/maplibre/maplibre-navigation-android/tree/main/sample/android/app)

This is a bit confusing.

[Fabi755]

Please have a look at the README. The app is using the core library, and also the Android UI library. While the sample one is only using the core.

https://github.com/maplibre/maplibre-navigation-android?tab=readme-ov-file#samples

Samples
Android
We have added an Android example app to this repo.

The Valhalla example is aready pre-configured. All other examples needs to be configured with your own tile and direction server. This URLs needs to be set in developer-config.xml, which is generated on first Gradle run.

Multiplatform
The new Kotlin Multiplatform library for iOS and Android has it's own small sample apps for all supported platforms.

[karussell]

It is IMO unclear what is the best way to get started. I used the multiplatform sample app, but maybe I should have used the other one as it is currently more tested or better supported? And will the multiplatform sample at some point replace the other sample?

[karussell]

Or maybe a different question. If I contribute that the example can be easily switched to using GraphHopper navigation, will such a PR accepted and if yes, which of the examples should I modify? Both?

[boldtrn]

but maybe I should have used the other one as it is currently more tested or better supported?

I think the non KMP sample is currently the best sample as it is a working navigation app, the KMP sample is really just showing that it works 😄.

If I contribute that the example can be easily switched to using GraphHopper navigation, will such a PR accepted and if yes, which of the examples should I modify

Sure 👍 - I'd suggest you add this as one more sample in the Android example app, as there is a switch already and you should get away with copy paste + some small changes :)

[karussell]

Thanks for the clarification!

I cloned the ValhallaNavigationActivity into a GraphHopperNavigationActivity and this seems to works as another example. One problem I had when I did not enable the GPS I got no error. And a second problem I (still) have is that the initial zoom is always too far away (maybe just the simulation?).

Regarding the multiplatform example: Could one use the resources like valhalla_url or is this no longer possible? And would you accept a change for it too? Basically I'd set provider="valhalla" and then set the request and URL according to this variable so that one can see how to use GraphHopper there too.

[boldtrn]

One problem I had when I did not enable the GPS I got no error. And a second problem I (still) have is that the initial zoom is always too far away (maybe just the simulation?).

While pretty mature, it is a sample app. You could implement your own Camera to set the zoom to the level you like. I think you should be also able to pass in your own GPS implementation.

Could one use the resources like valhalla_url or is this no longer possible?

The core has no http request logic. It is really focused about navigation. You would need to implement your own client or reuse for example the Maplibre-Java SDK that is used in the UI module.

And would you accept a change for it too?

Yes, but please note, this would be a bit of a bigger change, because you would have to either do this in KMP core or a new module. Or at the very least, create interfaces in the core that you implement on the Android side and iOS side using for example the GraphHpper or Mapbox Directions Client.

In general, we are very open for PRs that improve this library and I am happy to review these changes.