Draw path on google map based on lat lang

Question

i want to draw path on google map.

Basically what i am tracking user locaion after specfic time interval. when user reach to some destination then i need to draw the path which he followed to reach that destination.

It is working fine but the problem is it is showing zigzag path. See the image below.

What i want:

I want to draw a proper path followed by the points that i get during tracking.

What i have tried

i searched and found this link in which we can pass up to 8 points to get the directions. Which is the maximum limit allowed to the non-business users of the Google Map. Is there any other way to achieve this. because i have so many points to draw on map.

code for drawing polylines

private void drawPath() {
        if (mMap != null)
            mMap.clear();
        int count = 0;
        LatLng prev = null;
        String[] mProjection = {LocTable.COLUMN_ID, LocTable.COLUMN_LONGITUDE, LocTable.COLUMN_LATITUDE};
        String mSelectionClause = LocTable.COLUMN_ID + "> ?";
        String[] mSelectionArgs = {"0"};
        String mSortOrder = LocTable.COLUMN_ID;

        Cursor mCursor = getContentResolver().query(
                LocContentProvider.CONTENT_URI,   // The content URI of the words table
                mProjection,                        // The columns to return for each row
                mSelectionClause,                    // Selection criteria
                mSelectionArgs,                     // Selection criteria
                mSortOrder); 


        if(mCursor != null && mCursor.getCount()!=0) {

            Log.i("cursor", "Count: " + mCursor.getCount() + "|Column count: " + mCursor.getColumnCount());
            if (mCursor.moveToFirst()) {
                do {
                    if (mMap != null) {

                        float lon = mCursor.getFloat(1);
                        float lat = mCursor.getFloat(2);
                        LatLng current = new LatLng(lat, lon);

                        markerPoints.add(current);
                        if (count == 0){
                            prev = current;
                        }
                        CameraUpdate cameraUpdate = CameraUpdateFactory.newLatLngZoom(current, 19);
                        mMap.animateCamera(cameraUpdate);
                        mMap.addPolyline((new PolylineOptions())
                                .add(prev, current).width(6).color(Color.BLUE)
                                .visible(true));
                        prev=current;
                        count++;
                    }
                } while (mCursor.moveToNext());
            }

            mCursor.close();
        }
    }

thanks for help.

Draw a polyline. You can pass a list of points (latlng) to the the Polyline and then add it to your map https://developers.google.com/android/reference/com/google/android/gms/maps/model/Polyline — Pedro Oliveira, May 10 '16 at 11:26
@Ravi i need to draw both type of paths... and in code i am just drawing polylines on google saved in local DB — Mustanser Iqbal, May 10 '16 at 11:43
@PedroOliveira i have added the code please check. what i am doing wrong here. — Mustanser Iqbal, May 10 '16 at 11:48
@MustanserIqbal if you want to draw proper path then you have to manually or every 5sec on save latlong then draw path — Ravi Vaghela, May 10 '16 at 12:28
no unfortunately not. i tried as you suggested but it is not working.. actually i get location from network (when possible) otherwise from gps and most of the time location is not accurate. and that is the reason for such type of path being drawn. — Mustanser Iqbal, May 11 '16 at 06:23
http://stackoverflow.com/questions/14444228/android-how-to-draw-route-directions-google-maps-api-v2-from-current-location-t — Sanat Chandravanshi, Jun 14 '16 at 06:06

score 6 · Answer 1 · edited May 23 '17 at 11:46

I'm agree with antonio's answer. Problem is not with you drawing function. You just drawing path whatever device giving you location. Problem is your device is not giving accurate location.

Let me giving you brief description about Location Functionality.

There are three kind of provider giving location in device.

1 GPS Provider.

This provider determines location using satellites. Depending on conditions, this provider may take a while to return a location fix. Requires the permission ACCESS_FINE_LOCATION.

The extras Bundle for the GPS location provider can contain the following key/value pairs:

satellites - the number of satellites used to derive the fix

2 Network Provider.

This provider determines location based on availability of cell tower and WiFi access points. Results are retrieved by means of a network lookup.

3 Passive Provider.

This provider can be used to passively receive location updates when other applications or services request them without actually requesting the locations yourself. This provider will return locations generated by other providers. You can query the getProvider() method to determine the origin of the location update. Requires the permission ACCESS_FINE_LOCATION, although if the GPS is not enabled this provider might only return coarse fixes.

Reference:

Android Location Manager

Android Location Providers - GPS or Network Provider?

As per my experience I can say GPS Provider is giving you accurate location compare to Network Provider but need open environment, GPS provider is not giving accurate location in inside building.

getAccuracy().

Returns a constant describing horizontal accuracy of this provider. If the provider returns finer grain or exact location, ACCURACY_FINE is returned, otherwise if the location is only approximate then ACCURACY_COARSE is returned.

This method will return exact value when location is changed from GPS Provider otherwise it will return approximate or 0 value.

Ref : Location.getAccuracy()

Solution:

Use only GPS Provider
Find out your location is accurate or not.

Recommended Use Google Client Sample Example.

score 4 · Answer 2 · answered Jun 07 '16 at 14:39

The problem is not on your drawing function but on the method you are using to get the points of your path using the received location.

You need to take into account two factors:

First of all, the accuracy of the received location. You can get the accuracy using the Location.getAccuracy() method (documentation). The accuracy is measured in meters, so the lower the better.
On the other hand, you may want to add a new location to your polyline only if your new location is farther than a given distance to your last added location.

An example combining both considerations:

private static final float MINIMUM_ACCURACY = 10; // If the accuracy of the measurement is worse than 10 meters, we will not take the location into account
private static final float MINIMUM_DISTANCE_BETWEEN_POINTS = 20; // If the user hasn't moved at least 20 meters, we will not take the location into account
private Location lastLocationloc;

// ...

public void onLocationChanged(Location mylocation) {
    if (mylocation.getAccuracy() < MINIMUM_ACCURACY) {
        if (lastLocationloc == null || lastLocationloc.distanceTo(mylocation) > MINIMUM_DISTANCE_BETWEEN_POINTS) {
            // Add the new location to your polyline

            lastLocationloc = mylocation;
        }
    }
}

score 1 · Answer 3 · answered Jun 14 '16 at 02:09

1

Have you looked into the new Roads Api? It will calculate the accuracy and returns the most reasonable values to draw the line from. It also provides the speed limit on the current road.

answered Jun 14 '16 at 02:09

The_Martian

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score 0 · Answer 4 · answered Jun 14 '16 at 12:53

Adding to @antonio answer. You can specify priority and displacement as follows. This will make sure you can receive maximum possible accuracy

    private int mInterval =5;
    private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 10;
    private static final float MIN_ACCURACY = 10;
    private Location lastKnownLocation;

            @Override
            public void onConnected(Bundle bundle) {

                locationRequest = LocationRequest.create();
                locationRequest.setInterval(mInterval * 1000); // milliseconds
                locationRequest.setFastestInterval(mInterval * 1000);
                locationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
                locationRequest.setSmallestDisplacement(MIN_DISTANCE_CHANGE_FOR_UPDATES);//distance change
                int permissionCheck = ContextCompat.checkSelfPermission(appContext, Manifest.permission.ACCESS_COARSE_LOCATION);
                if (permissionCheck!= PackageManager.PERMISSION_DENIED)
                {    LocationServices.FusedLocationApi.requestLocationUpdates(googleApiClient,
 locationRequest, this);
                }
            }

Now in the onLocationChanged method do as per suggestion.

@Override
    public void onLocationChanged(Location location) {
        if (location.getAccuracy() < MIN_ACCURACY ) {
            if (lastKnownLocation == null || lastKnownLocation.distanceTo(location) > MIN_DISTANCE_CHANGE_FOR_UPDATES) {

                lastKnownLocation = location;
            }
        }
    }

NOTE :

While retrieving location from NetworkProvider which is faster, even if device is static the received location within specific intervals varies. The above logic will give us the opportunity to avoid the irrelevant values and track/process the valid ones.

Fused Location Provider Api Details

Draw path on google map based on lat lang

4 Answers4

1 GPS Provider.

2 Network Provider.

3 Passive Provider.

getAccuracy().

Linked