[Help Wanted]: Need help on Distance calculation

[yaswanthsaiaddala]

Required Reading

• Confirmed

Plugin Version

4.16.9

Mobile operating-system(s)

• iOS
• Android

Device Manufacturer(s) and Model(s)

Samsung S21

Device operating-systems(s)

Android 15

What do you require assistance about?

I’m noticing some discrepancies in the distance calculation. Do we have any standard or predefined methods for accurately calculating distance?

[Optional] Plugin Code and/or Config

bg.Config(
            url: ENV.TRACKER_HOST, // <-- your server url
            // reset:
            //     false, // <-- lets the Settings screen drive the config rather than re-applying each boot.
            // // Convenience option to automatically configure the SDK to post to Transistor Demo server.
            transistorAuthorizationToken: token,
            // Logging & Debug
            debug: false,
            logLevel: bg.Config.LOG_LEVEL_VERBOSE,
            // Geolocation options
            desiredAccuracy: bg.Config.DESIRED_ACCURACY_NAVIGATION,
            distanceFilter: 10.0,
            // Activity recognition options
            stopTimeout: 5,
            backgroundPermissionRationale: bg.PermissionRationale(
                title:
                    "Allow {applicationName} to access this device's location even when the app is closed or not in use.",
                message:
                    "This app collects location data to enable recording your trips to work and calculate distance-travelled.",
                positiveAction: 'Change to "{backgroundPermissionOptionLabel}"',
                negativeAction: 'Cancel'),
            // HTTP & Persistence
            autoSync: true,
            // Application options
            stopOnTerminate: false,
            startOnBoot: true,
            enableHeadless: true,
            heartbeatInterval: 60)

bg.BackgroundGeolocation.setConfig(bg.Config(
          transistorAuthorizationToken: jwt,
          params: {
            "empId": username,
            "token": token,
          },
          desiredOdometerAccuracy: 10,
          disableStopDetection: true,
          maxDaysToPersist: 2,
          forceReloadOnBoot: true,
          allowIdenticalLocations: false,
          locationAuthorizationAlert: {
            'titleWhenNotEnabled': 'Yo, location-services not enabled',
            'titleWhenOff': 'Yo, location-services OFF',
            'instructions':
                'You must enable \'Always\' in location-services, buddy',
            'cancelButton': 'Cancel',
            'settingsButton': 'Settings'
          },
          notification: bg.Notification(
            title: "Sandhya Feed",
            text: "Tracking your location in the background",
          )))

[Optional] Relevant log output

07-04 10:56:10.009  3223  3223 W TSLocationManager: [c.t.f.b.BackgroundGeolocationModule ready] 
07-04 10:56:10.009  3223  3223 W TSLocationManager:   ⚠️  #ready already called.  Redirecting to #setConfig
07-04 10:56:10.016  3223  3349 I TSLocationManager: [c.t.l.http.HttpService flush] 
07-04 10:56:10.016  3223  3349 I TSLocationManager: ╔═════════════════════════════════════════════
07-04 10:56:10.016  3223  3349 I TSLocationManager: ║ HTTP Service (count: 0)
07-04 10:56:10.016  3223  3349 I TSLocationManager: ╠═════════════════════════════════════════════
07-04 10:56:11.769  3223  3349 I TSLocationManager: [c.t.l.http.HttpService flush] 
07-04 10:56:11.769  3223  3349 I TSLocationManager: ╔═════════════════════════════════════════════
07-04 10:56:11.769  3223  3349 I TSLocationManager: ║ HTTP Service (count: 0)
07-04 10:56:11.769  3223  3349 I TSLocationManager: ╠═════════════════════════════════════════════
07-04 10:56:11.779  3223  3349 I TSLocationManager: - Enable: false → true, trackingMode: 1
07-04 10:56:11.779  3223  3349 I TSLocationManager: [c.t.l.g.TSGeofenceManager start] 
07-04 10:56:11.779  3223  3349 I TSLocationManager:   🎾  Start monitoring geofences
07-04 10:56:11.789  3223  3349 I TSLocationManager: [c.t.l.s.ActivityRecognitionService start] 
07-04 10:56:11.789  3223  3349 I TSLocationManager:   🎾  Start motion-activity updates
07-04 10:56:11.793  3223  3349 I TSLocationManager: [c.t.l.service.HeartbeatService start] 
07-04 10:56:11.793  3223  3349 I TSLocationManager:   🎾  Start heartbeat (60s)
07-04 10:56:11.794  3223  3349 I TSLocationManager: [c.t.l.s.TSScheduleManager oneShot] 
07-04 10:56:11.794  3223  3349 I TSLocationManager:   ⏰ Scheduled OneShot: HEARTBEAT in 60000ms (jobID: -1307475748)
07-04 10:56:11.797  3223  3349 I TSLocationManager: [c.t.l.service.TrackingService changePace] 
07-04 10:56:11.797  3223  3349 I TSLocationManager:   🔵  setPace: false → false
07-04 10:56:11.807  3223  3223 I TSLocationManager: [c.t.l.l.TSLocationManager a] 
07-04 10:56:11.807  3223  3223 I TSLocationManager: ╔═════════════════════════════════════════════
07-04 10:56:11.807  3223  3223 I TSLocationManager: ║ motionchange LocationResult: 3 (84928ms old)
07-04 10:56:11.807  3223  3223 I TSLocationManager: ╠═════════════════════════════════════════════
07-04 10:56:11.807  3223  3223 I TSLocationManager: ╟─ 📍  Location[fused 17.484051,78.377051 hAcc=12.178 et=+2d23h53m15s697ms alt=531.7999877929688 vAcc=0.63916665 vel=0.133382 sAcc=1.5 bear=110.67838 bAcc=45.0], time: 1751606686879
07-04 10:56:11.819  3223  3349 I TSLocationManager: [c.t.l.l.SingleLocationRequest startUpdatingLocation] 
07-04 10:56:11.819  3223  3349 I TSLocationManager:   🔵  [SingleLocationRequest start, action: 1, requestId: 3]
07-04 10:56:11.839  3223  3349 I TSLocationManager: [c.t.l.s.LocationRequestService b] 
07-04 10:56:11.839  3223  3349 I TSLocationManager:   ℹ️  Location availability: false
07-04 10:56:12.795  3223  3349 I TSLocationManager: [c.t.l.http.HttpService flush] 
07-04 10:56:12.795  3223  3349 I TSLocationManager: ╔═════════════════════════════════════════════
07-04 10:56:12.795  3223  3349 I TSLocationManager: ║ HTTP Service (count: 0)
07-04 10:56:12.795  3223  3349 I TSLocationManager: ╠═════════════════════════════════════════════
07-04 10:56:13.199  3223  3349 I TSLocationManager: [c.t.l.s.LocationRequestService b] 
07-04 10:56:13.199  3223  3349 I TSLocationManager:   ℹ️  Location availability: true
07-04 10:56:13.208  3223  3349 I TSLocationManager: [c.t.l.l.TSLocationManager a] 
07-04 10:56:13.208  3223  3349 I TSLocationManager: ╔═════════════════════════════════════════════
07-04 10:56:13.208  3223  3349 I TSLocationManager: ║ motionchange LocationResult: 3 (102ms old)
07-04 10:56:13.208  3223  3349 I TSLocationManager: ╠═════════════════════════════════════════════
07-04 10:56:13.208  3223  3349 I TSLocationManager: ╟─ 📍  Location[fused 17.484047,78.377041 hAcc=11.883 et=+2d23h54m41s923ms alt=531.7999877929688 vAcc=0.63684607], time: 1751606773104
07-04 10:56:13.211  3223  3349 I TSLocationManager: [c.t.l.l.TSLocationManager onSingleLocationResult] 
07-04 10:56:13.211  3223  3349 I TSLocationManager:   🔵  Acquired motionchange position, isMoving: false
07-04 10:56:13.219  3223  4105 I TSLocationManager: [c.t.l.d.s.SQLiteLocationDAO persist] 
07-04 10:56:13.219  3223  4105 I TSLocationManager:   ✅  INSERT: 63e6960d-a128-43c4-aae5-9a7ee5e8bc8f
07-04 10:56:13.224  3223  4105 I TSLocationManager: [c.t.l.http.HttpService flush] 
07-04 10:56:13.224  3223  4105 I TSLocationManager: ╔═════════════════════════════════════════════
07-04 10:56:13.224  3223  4105 I TSLocationManager: ║ HTTP Service (count: 1)
07-04 10:56:13.224  3223  4105 I TSLocationManager: ╠═════════════════════════════════════════════
07-04 10:56:13.233  3223  3223 I TSLocationManager: [c.t.l.service.TrackingService k] 
07-04 10:56:13.233  3223  3223 I TSLocationManager: ╔═════════════════════════════════════════════
07-04 10:56:13.233  3223  3223 I TSLocationManager: ║ TrackingService motionchange: false
07-04 10:56:13.233  3223  3223 I TSLocationManager: ╠═════════════════════════════════════════════
07-04 10:56:13.278  3223  3223 I TSLocationManager: [c.t.l.u.BackgroundTaskManager$Task start] ⏳ startBackgroundTask: 3
07-04 10:56:13.280  3223  4105 I TSLocationManager: [c.t.l.http.HttpService a] 
07-04 10:56:13.280  3223  4105 I TSLocationManager:   🔵  HTTP POST: 63e6960d-a128-43c4-aae5-9a7ee5e8bc8f
07-04 10:56:14.563  3223  4270 I TSLocationManager: [c.t.l.http.HttpService$f onResponse] 
07-04 10:56:14.563  3223  4270 I TSLocationManager:   🔵  Response: 200
07-04 10:56:14.575  3223  4270 I TSLocationManager: [c.t.l.u.BackgroundTaskManager$Task stop] ⏳ stopBackgroundTask: 3

[christocracy]

How are you calculating distance?

You could use this plugin latlong

[yaswanthsaiaddala]

that plugin is not compatible with Dart 3

[christocracy]

Is there a maintained fork? Yes there is:

https://github.com/jifalops/dart-latlong

https://pub.dev/packages/latlong2

[yaswanthsaiaddala]

Hi, I am using my own server, I am hitting the server with the desired payload

locationTemplate:
'{ "latitude": "<%= latitude %>", "longitude": "<%= longitude %>", "heading": -1, "timestamp": "<%= timestamp %>"}',

Do we have any scope to view network calls that are going through plugin?

I am getting error response as below

{"$id":"1","type":"https://tools.ietf.org/html/rfc9110#section-15.5.1","title":"One or more validation errors occurred.","status":400,"errors":{"$id":"2","Latitude":["The Latitude field is required."],"Longitude":["The Longitude field is required."]},"traceId":"00-b7183ff64f8a9a71d30015c357d3229c-44987c70473b59ab-00"}
07-17 20:58:10.524 25391 25427 I flutter : [http] - [HttpEvent {success: false, status: 400, responseText: {"$id":"1","type":"https://tools.ietf.org/html/rfc9110#section-15.5.1","title":"One or more validati...}]

[yaswanthsaiaddala]

Hi, I am using my own server, I am hitting the server with the desired payload

locationTemplate: '{ "latitude": "<%= latitude %>", "longitude": "<%= longitude %>", "heading": -1, "timestamp": "<%= timestamp %>"}',

Do we have any scope to view network calls that are going through plugin?

I am getting error response as below

{"$id":"1","type":"https://tools.ietf.org/html/rfc9110#section-15.5.1","title":"One or more validation errors occurred.","status":400,"errors":{"$id":"2","Latitude":["The Latitude field is required."],"Longitude":["The Longitude field is required."]},"traceId":"00-b7183ff64f8a9a71d30015c357d3229c-44987c70473b59ab-00"} 07-17 20:58:10.524 25391 25427 I flutter : [http] - [HttpEvent {success: false, status: 400, responseText: {"$id":"1","type":"https://tools.ietf.org/html/rfc9110#section-15.5.1","title":"One or more validati...}]

Suggest me if I do anything mistake in payload

My required payload is

{
"latitude":17.4840558,
"longitude":78.3770411,
"timestamp":"2025-07-17T04:38:28.986Z",
"heading":-1
}