Develop Reference

Follow me Mission TimeOut DJI SDK

I am trying to create a custom FollowMe mission by sending a vehicle's GPS data on Android studio. i can send the vehicle coordinates,but the updateFollowingTarget gives a timeout error.I'm using mavic 2 zoom and dji sdk v1.14 .Did someone manage to fix this issue.
Thanks in advance.

It's a bug. It always returns timeout.
Just dont care about the error and it will work.
But it speed limited to like 15km/h so dont expect to much from it.
Edited (Do you know another function that i can use to follow a vehicle's GPS signal):
Yes, it involves more programming though.
You have to use virtualstick to control the drone. This is the only way to control the drone programmatically.
I have done it here, follows a tracker app running on a phone on my head:
https://www.youtube.com/watch?v=i3axYfIOHTY
Im working on a python api for dji. In that framework the top level code looks like below. The virtualstick calls are inside move_towards():
while True:
tracker_location = api.tracker.get_location()
drone_target_location = copy.deepcopy(tracker_location).move_to(Changeable.radius.get_value(), Changeable.bearing.get_value())
drone_location = api.drone.get_location()
course_to_tracker = drone_location.get_course(tracker_location)
heading = api.drone.smooth_heading(course_to_tracker)
drone_target_distance, drone_speed, course = api.drone.move_towards(drone_target_location, height=current_altitude, heading=heading, lowest_altitude=Changeable.lowest_altitude.get_value(), deadzone=[Changeable.dead_zone0.get_value(), Changeable.dead_zone1.get_value()], k_distance=[float(Changeable.k_dist0.get_value()), float(Changeable.k_dist1.get_value())], speed_deadzone=Changeable.speed_deadzone.get_value())

Sound metering react-native

Im building a react-native application.
Im trying to meter the current sound level (in decibel).
Libraries in use: react-native-audio and react-native-sound.
There is anybody familiar with this feature?
Thank you.

With the react-native-audio library, you can get the count for the only iOS.
For the currentMetering in Android, you need to customize in a native module. I have updated it add the following things in your package.json file instead of your code. You will get the currentMetering count for the Android as well as iOS.
"react-native-audio": "git+https://github.com/Harsh2402/react-native-audio.git",

You can use react-native-audio currentMetering value - in order to get the sound level in real-time.
First, you will have to initialise your recorder (which i will assume youve done). I use prepareRecordingAtPath in a similar way to below
AudioRecorder.prepareRecordingAtPath(audioPath, {
SampleRate: 22050,
Channels: 1,
AudioQuality: "Low",
AudioEncoding: "aac",
MeteringEnabled: true
});
then once you've called AudioRecorder.startRecording(); (Note you have access to .pause() and .stop() methods also
Now for handling the audio level, you are going to have to retrieve the data that is returned by the onProgress method. From what i remember, there should be some currentMetering value that you can access. Note that defining this behaviour will trigger the action every time a different decibel reading is retrieved. Like so
AudioRecorder.onProgress = data => {
let decibels = Math.floor(data.currentMetering);
//DO STUFF
};
Hope this helps,

Detecting Mock Location Not Working (Android)

I'm trying to set some protection against people using mock locations to manipulate my app. I realise that it's impossible to prevent 100%... I'm just trying to do what I can.
The app uses Google location services (part of play services) in its main activity.
The onLocationChanged() method is:
public void onLocationChanged(Location location) {
this.mCurrentLocation = location;
if (Build.VERSION.SDK_INT > 17 && mCurrentLocation.isFromMockProvider()) {
Log.i(TAG, "QQ Location is MOCK");
// TODO: add code to stop app
// otherwise, currently, location will never be updated and app will never start
} else {
Double LAT = mCurrentLocation.getLatitude();
Double LON = mCurrentLocation.getLongitude();
if ((LAT.doubleValue() > 33.309171) || (LAT.doubleValue() < 33.226442) || (LON.doubleValue() < -90.790165) || (LON.doubleValue() > -90.707081)) {
buildAlertMessageOutOfBounds();
} else if (waiting4FirstLocationUpdate) {
Log.i(TAG, "YYY onLocationChanged() determines this is the FIRST update.");
waiting4FirstLocationUpdate = false;
setContentView(R.layout.activity_main);
startDisplayingLists();
}
}
}
The location services work perfectly and all is well with the app in general, but when I run the app in an emulator with Android Studio (Nexus One API 23), and I set the location using extended controls (mock), the app just continues to work as normal, and so it seems that the condition:
if (Build.VERSION.SDK_INT > 17 && mCurrentLocation.isFromMockProvider())
Is returning false.
This doesn't make any sense to me. Does anyone know why this would happen?
Thanks!

The short answer: .isFromMockProvider is unreliable. Some fake locations are not properly detected as such.
I have spent an extensive amount of time researching this and written a detailed blog post about it.
I also spent time to find a solution to reliably suppress mock locations across all recent/relevant Android versions and made a utility class, called the LocationAssistant, that does the job.
In a nutshell (using the aforementioned LocationAssistant):
Set up permissions in your manifest and Google Play Services in your gradle file.
Copy the file LocationAssistant.java to your project.
In the onCreate() method of your Activity, instantiate a LocationAssistant with the desired parameters. For example, to receive high-accuracy location updates roughly every 5 seconds and reject mock locations, call new LocationAssistant(this, this, LocationAssistant.Accuracy.HIGH, 5000, false). The last argument specifies that mock locations shouldn't be allowed.
Start/stop the assistant with your Activity and notify it of permission/location settings changes (see the documentation for details).
Enjoy location updates in onNewLocationAvailable(Location location). If you chose to reject mock locations, the callback is only invoked with non-mock locations.
There are some more methods to implement, but essentially this is it. Obviously, there are some ways to get around mock provider detection with rooted devices, but on stock, non-rooted devices the rejection should work reliably.

Aerial Photo Map in OSMDroid - Bing? or What?

I have a requirement for building an Android mapping application onto which I will plot archaeological POIs (Points of interest). The requirement is to have aerial photographs much like Google Maps Satellite view. However, the other requirement is offline mapping capability when data connectivity is unavailable, so that rules out using Google Maps.
So I have two questions.
Does OSMDroid have free access to tile sources supporting Arial Photography or Satellite without using Bing?.
I know OSM can support Bing which does have an Ariel Photography map, but I can't get it to work. Are there any bing specific tutorials you can point me to, or a simple example of how to get a bing map to show in OSMDroid as I've been looking for some hours and pulling my hair out.
In eclise I have been able to build a simple app to show the default maps of OSMDroid (Mapink). To try and use Bing I added into my project source three classes. BingMapTileSource.Java, ImageryMetaData.Java and ImageryMetaDataResouce.Java. I got these from the Bing sub folder of the TileProvider directory on the OSMDroid SVN (Link here)
However, when I use this in the onCreate as follows, I get null pointer errors in the BingMapTileSource.java class.
MapView mapView = new MapView(this, 256);
mapView.setClickable(true);
mapView.setBuiltInZoomControls(true);
String m_locale=Locale.getDefault().getISO3Language()+"-"+Locale.getDefault().getISO3Language();
mapView.setTileSource(new BingMapTileSource("Bing",m_locale));
mapView.getController().setZoom(10);
mapView.getController().setCenter(new GeoPoint(39.461078, 2.856445));
setContentView(mapView);
I beleive the cause of this problem is that the following class variables are never initialised before they are first used.
s_roadMetaData = null;
s_aerialMetaData = null;
s_aerialwithLabelsMetaData = null;
The only place I can see them being initialised is in a static method called InitMetaData which never gets called.
public static synchronized void initMetaData(final Context aContext)
Though some clue as to its purpose is provided in its Javadoc which states.
/**
* Initialize BingMap tile source.<br>
* This method should be invoked before class instantiation.<br>
* It get dynamically the REST service url to be used to get tile in each supported map view mode.
* #param a_BingMapKey The user's BingMap key.
* #throws Exception
*/
However, I've no idea how to use this. Any advice or pointers to tutorials, examples, or some code would be greatly appreciated.

updated 22.07.2015
How to add Bing maps to osmdroid
Here are step by step instructions. Perhaps someone this will save a lot of time.
1.Add dependency to gradle
compile 'org.slf4j:slf4j-android:1.6.1-RC1'
compile 'org.osmdroid:osmdroid-android:4.3'
2.add library osmdroid-third-party from here
OR
add three classes in our project (BingMapTileSource.java, ImageryMetaData.java, ImageryMetaDataResource.java). from here
3.Getting a Bing Maps Key. Instructions here
4.Add the Bing Maps Key to the manifest.
<meta-data android:name="BING_KEY" android:value="ApEqyap8rTa4WTNCNv-3pAGQc7XUsHS6595tuDI3MHR59QlahJ5bqYGYhMYJq6Ae" />
5.The last step. Add map code
ResourceProxyImpl mResourceProxy = new ResourceProxyImpl(getContext().getApplicationContext());
MapView mMapView = new MapView(getContext(), 256, mResourceProxy);
mMapView.setBuiltInZoomControls(true);
mMapView.setMultiTouchControls(true);
try{
BingMapTileSource.retrieveBingKey(getContext());
String m_locale = Locale.getDefault().getDisplayName();
BingMapTileSource bing = new BingMapTileSource(m_locale);
bing.setStyle(BingMapTileSource.IMAGERYSET_AERIAL);
mMapView.setTileSource(bing);
}
catch(Exception e){
e.printStackTrace();
}
mapContent.addView(mMapView);

The requirement for offline satellite images means that you will have to license the imagery separately. I don't think any of the providers allow such usage without a specific agreement.

There are many commercial providers for aerials: Digitalglobe, Geoeye etc. Check from Google Earth, they mention their providers in bottom of the map.
There are also some lower resolution free images like OpenAerialMap, which itself is not working anymore. But it is worth to check their original sources (http://openaerialmap.org/Data_Sources). Also at least some of their remaining archive is available in MapQuest Open Tiles API. Maybe they even allow downloading to offline, check their terms.
Two warnings through - aerial imagery from commercial providers can be quite expensive, especially for offline case. And aerials from any source will take a lot of space, several times more than raster tiles. So just downloading them to the device can be a challenge.

Ok well I figured the problem with getting the Bing maps to work. What was needed was to precede the instantiation of the BingMapTileSouce with the following static method that instantiates the three Meta Data objects discussed earlier.
try
{
BingMapTileSource.initMetaData(this);
}
catch (Exception e)
{
e.printStackTrace();
}

How to get user position by GPS in Sencha

I'm trying to get user position in Sencha Touch 2:
var geo = new Ext.util.Geolocation({
autoUpdate: true,
allowHighAccuracy: true,
listeners: {
locationupdate: function(geo) {
lat = geo.getLatitude();
lon = geo.getLongitude();
// here comes processing the coordinates
}
}
});
But I've got coordinates only from network. There's no GPS icon on Android device, pointing that I'm using GPS. Also it doesn't work when I turn off internet connection. How can I enable GPS positioning? In Manifest file GPS is enabled.

I just got bit by this too.
It turns out there's a bug in Sencha: in Ext.util.Geolocation.parseOption they name the parameter allowHighAccuracy but the w3c specs name it enableHighAccuracy.
I added the following code to my application init to fix that:
var parseOptions = function() {
var timeout = this.getTimeout(),
ret = {
maximumAge: this.getMaximumAge(),
// Originally spells *allowHighAccurancy*
enableHighAccuracy: this.getAllowHighAccuracy()
};
//Google doesn't like Infinity
if (timeout !== Infinity) {
ret.timeout = timeout;
}
return ret;
};
Ext.util.Geolocation.override('parseOptions', parseOptions);
For the record: the bug has been reported over a year ago, and the fix was applied for TOUCH-2804 in a recent build. I don't know what that means, but sure enough the bug is still in 2.0
EDIT: using the approach mentioned above doesn't work well either. The GPS icon would turn on and off as Exts calls getCurrentPosition repeatedly using a setInterval. The reason for doing this is that The native watchPosition method is currently broken in iOS5. In my Android targeted application I ended up ditching Ext:util.Geolocation and directely used navigator.geolocation.watchPosition. After that it worked like a charm.

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

Hey I think you need updated longitude and latitude values .
follow this link.. Click Here
I already tried it and test it in android mobile phone.. Its working.
Note : Must and should test in android mobile phone with on GPS status. It will not show on eclipse emulator. But it will show in mobile phone try it..
have a nice.