plausibility check for the first location (which sometimes can be wrong)

app/src/main/java/org/y20k/trackbook/Keys.kt

@@ -99,6 +99,7 @@ object Keys {
     const val ADD_WAYPOINT_TO_TRACK_INTERVAL: Long = 15000L                     // 15 seconds in milliseconds
     const val SIGNIFICANT_TIME_DIFFERENCE: Long = 120000L                       // 2 minutes in milliseconds
     const val STOP_OVER_THRESHOLD: Long = 300000L                               // 5 minutes in milliseconds
+    const val IMPLAUSIBLE_TRACK_START_SPEED: Double = 250.0                     // 250 km/h
     const val DEFAULT_LATITUDE: Double = 71.172500                              // latitude Nordkapp, Norway
     const val DEFAULT_LONGITUDE: Double = 25.784444                             // longitude Nordkapp, Norway
     const val DEFAULT_ACCURACY: Float = 300f                                    // in meters

app/src/main/java/org/y20k/trackbook/helpers/LengthUnitHelper.kt

@@ -92,4 +92,17 @@ object LengthUnitHelper {
         return imperialSystemCountries.contains(countryCode)
     }
 
+
+    /* Coverts meters per second to either km/h or mph */
+    fun convertMetersPerSecond(metersPerSecond: Float, useImperial: Boolean = false): Double {
+        if (useImperial) {
+            // mph
+            return metersPerSecond * 2.2369362920544
+        } else {
+            // km/h
+            return metersPerSecond * 3.6
+        }
+    }
+
+
 }

app/src/main/java/org/y20k/trackbook/helpers/LocationHelper.kt

@@ -155,6 +155,26 @@ object LocationHelper {
     }
 
 
+    /* Checks if the first location of track is plausible */
+    fun isFirstLocationPlausible(secondLocation: Location, track: Track): Boolean {
+        // speed in km/h
+        val speed: Double = calculateSpeed(firstLocation = track.wayPoints[0].toLocation(), secondLocation = secondLocation, firstTimestamp = track.recordingStart.time, secondTimestamp = GregorianCalendar.getInstance().time.time)
+        // plausible = speed under 250 km/h
+        return speed < Keys.IMPLAUSIBLE_TRACK_START_SPEED
+    }
+
+
+    /* Calculates speed */
+    private fun calculateSpeed(firstLocation: Location, secondLocation: Location, firstTimestamp: Long, secondTimestamp: Long, useImperial: Boolean = false): Double {
+        // time difference in seconds
+        val timeDifference: Long = (secondTimestamp - firstTimestamp) / 1000L
+        // distance in meters
+        val distance: Float = calculateDistance(firstLocation, secondLocation)
+        // speed in either km/h (default) or mph
+        return LengthUnitHelper.convertMetersPerSecond(distance / timeDifference, useImperial)
+    }
+
+
     /* Checks if given location is different enough compared to previous location */
     fun isDifferentEnough(previousLocation: Location?, location: Location): Boolean {
         // check if previous location is (not) available
@@ -173,7 +193,7 @@ object LocationHelper {
     }
 
 
-    /* Calculates distance between two locations */
+    /* Calculates distance in meters between two locations */
     fun calculateDistance(previousLocation: Location?, location: Location): Float  {
         var distance: Float = 0f
         // two data points needed to calculate distance

app/src/main/java/org/y20k/trackbook/helpers/TrackHelper.kt

@@ -46,13 +46,22 @@ object TrackHelper {
 
     /* Adds given locatiom as waypoint to track */
     fun addWayPointToTrack(track: Track, location: Location, locationAccuracyThreshold: Int, resumed: Boolean): Pair<Track, Boolean> {
-
         // get previous location
         val previousLocation: Location?
-        val numberOfWayPoints: Int = track.wayPoints.size
+        var numberOfWayPoints: Int = track.wayPoints.size
+
+        // CASE: First location
         if (numberOfWayPoints == 0) {
             previousLocation = null
-        } else {
+        }
+        // CASE: Second location - check if first location was plausible & remove implausible location
+        else if (numberOfWayPoints == 1 && !LocationHelper.isFirstLocationPlausible(location, track)) {
+            previousLocation = null
+            numberOfWayPoints = 0
+            track.wayPoints.removeAt(0)
+        }
+        // CASE: Third location or second location (if first was plausible)
+        else {
             previousLocation = track.wayPoints.get(numberOfWayPoints - 1).toLocation()
         }
 

build.gradle

@@ -1,7 +1,7 @@
 // Top-level build file where you can add configuration options common to all sub-projects/modules.
 
 buildscript {
-    ext.kotlin_version = '1.3.61'
+    ext.kotlin_version = '1.3.71'
     repositories {
         google()
         jcenter()
@@ -10,7 +10,7 @@ buildscript {
     dependencies {
         classpath 'com.android.tools.build:gradle:3.6.1'
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
-        classpath "androidx.navigation:navigation-safe-args-gradle-plugin:2.2.0"
+        classpath "androidx.navigation:navigation-safe-args-gradle-plugin:2.2.1"
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files
     }