I'm currently searching a way for device using firefox OS to communicate with device's gps, so it can get the exact location positioning, rather than the w3c geolocation api which is not as accurate as gps realtime.. Thanks!
Simple answer: it isn't possible to access the "device's GPS" directly. You only have the Geolocation API that you already know.
Long answer: My experience with it is not bad at all. So, I think only of two possibilities for not getting "exact location positioning", as you name it:
maybe you're not using the right options to get a precise position. In this case, you could tweak your options a bit to get better results;
maybe you're not waiting until the underlying software can use your GPS instead of some less accurate instrument/estimation (like Wi-Fi positioning estimation).
It can be a combination of both =P
In the first case, you can verify if you're using enableHighAccuracy, like this:
navigator.geolocation.watchPosition(
successCallback,
errorCallback,
{ enableHighAccuracy: true }
);
This will ask the browser for better results, as the standard indicates. Watch out that this may use more battery, and this may not be available anyway. This may take more time too, which is related to my other observation.
In the second case, you may be using a value for timeout that is too small, and maybe it's combined with a maximumAge that may be too high.
If maximumAge is high and timeout is small, you get an out dated position, as there won't be enough time to get a new position and you accept an old one.
If both are small, you'll start to get lots of TIMEOUT errors (the value is 3), as there'll be no positions for you.
You need to find the right balance between all 3 options to get the best positions. And you have to be patient sometimes.
Play with all 3 options and take a look at the errors you get. They'll tell you a lot about your issue getting precise and accurate coordinates.
The position object has some attributes that may come in handy to analyze what's happaning:
the position.timestamp attribute will tell you how old that position object is. If this is old, you know you should tweak the options
the position.coords.accuracy attribute will tell you the accuracy level of the lat/long coordinates. If this is too big (it's in meters), you know you should tweak the options
If you wait forever, on a place where the GPS should work well (say, outdoors, on a clean field), and you keep getting inaccurate results, maybe you can't do much better anyway. I'd say it's not possible anyway, with your software+hardware =(
As of now, Firefox OS only has support for GPS positioning (with the latest addition of A-GPS in the mix). That results in the fact, that most of the time you will have to wait from 1 to several minutes at least for the GPS module to acquire lock on your location, and you will need clear look at the sky for the lock to be acquired.
That said, after a lock is acquired, by using the right settings in the call itself (like setting the enableHighAccuracy flag to true) the GPS should provide as accurate position as any other device would.
Right now cell-based and wifi-based geolocation is not available in the current version of the OS (1.0.1 or 1.1.0, either) but is in the pipeline.
You can use the Geolocation API Firefox OS or Google Maps (I do not remember where I got it)
Related
I am working on a feature in an iOS app to send location updates to our backend when there is a change in the location.
Initially, I had set minimalDistanceFilter(minimum change in location value) to none to send location updates. But it is making the network calls continuously and it can increase the load on the backend.
If some of you worked on this case earlier, I wanted to know how you solved it. What can be the minimalDistanceFilter?
I am also curious about how the above-listed apps work with location-related events.
The distanceFilter and the desiredAccuracy go hand-in-hand. For the distance filter, it can be anything between kCLDistanceFilterNone and CLLocationDistanceMax. See the documentation.
Regarding what other people used, it will vary widely from app to app. For navigation apps, you tend to need high accuracy so you don't miss a turn. But a weather app might be perfectly happy with city-level accuracy.
If you really need reasonable precision and want to reduce volume, then a filter of 5–15 meters is a good starting point. Try different values yourself and see what the effect is.
But there is no magical answer to your question. You will have to balance the legitimate needs of your app with (a) the server load; and (b) the power consumption on the device.
By the way, if the app doesn't need high accuracy, you might contemplate the very efficient, but less accurate, significant change service which will report changes of roughly 500 meters, with a frequency not exceeding once every 5 minutes
Finally, remember, nowadays the user is in control of the accuracy. You can request whatever accuracy you want, but if the user wants to preserve their privacy, they can choose not to share their precise location, and there is nothing you can do about it (other than to try to make a case for why precise location data is essential for the proper functioning of your app).
On iOS we are using the GPS to track users.
We had a strange case last week where a user were moving quite good, and then suddenly one point from the GPS could be totally off (~500 meters), and then moved again and then suddenly a totally off point again (again about 500 meters).
We are using filter and have set the accuracy to only get good GPS-points, and these kind of bad GPS-coordinates is nothing we normally see.
Because of this behaviour I started to think about how the GPS works in iOS when multiple apps are using the GPS at the same time.
We require a good accuracy, We use kCLLocationAccuracyBestForNavigation or kCLLocationAccuracyBest. They should only use the GPS and not any wifi/cellular or similar. We also filter out anything with an accuracy (fault tolerance) higher than 130.
But what happen if another app is also using the GPS with the settings of kCLLocationAccuracyThreeKilometers. Could it be that our app receives those updates and therefore we get bad accuracy because of that?
I need to allow manual positioning over a map if user location remains under a given accuracy a certain amount of time.
I need a way to test this circumstance. It's not like disable location services. Just want to have bad GPS signal (for example: horizontalAccuracy about 500 m. or so). "Unfortunately", in the place I work (my own house) I have a strong GPS signal so I can't test and fine tune the app behavior.
I wonder if there's a way to do this. Something like the network link conditioner in the developer menu on iPhone settings.
As far as I know, there's no way to do it short of writing a test class to inject location data. (I.e., there's nothing in the location simulation functionality provided by the simulator and/or debugger that will allow you to set accuracy.)
This answer to a similar question has an example of the manual-test-class-hackery way.
I am currently working on an app which requires the current region in which the user is in.The worst part is app is completely off line.
My logic :
1.Take a screen shot of the city draw squares on that.
Store square 4 points (lat long values taken with respect to map) in DB.
With the lat long values got from gps i can easily find out lat lont belongs to what reason.
I am just wondering if anybody can suggest me better idea to work my app offline.
Thank you in advance ..
You will probably find you have problems getting a location if you have no network access. iOS uses assisted-GPS, which allows the device to both lock onto GPS satellites much faster than it might otherwise take, and also pull in other data from the network to quickly determine location.
Without network access you may not get a location reported back at all, especially if the app was being used indoors (vanilla GPS reception is typically very bad without line of sight). If you do get a location it may take several minutes for an accurate enough reading to be provided.
you can use the RouteMe library which is based on OpenStreetMap. this allows to download map data in advance.
If you want to work with screenshots (from a legal source) then you use the Helmert transformation to transform between gps and picture-pixel coordinazes.
you need at least 3 points in the picture-map for which you now the lat,lon coordinates.
This is stated in CLLocationManager class reference:
When requesting high-accuracy location data, the initial event delivered by the location service may not have the accuracy you requested.
This is really affecting my app. How can I make sure that the location found is the one with the correct accuracy?
I tried to use the 4th or 5th update rather than first retrieved location but this is not a good solution. Any idea?
You should check the accuracy of the updates, CLLocation
contains a property horizontalAccuracy which you can use to check the accuracy.
When the CLLocation has an accuracy that you find accurate enough you use and ignore al others.
Als you should tel CLLocationManager your desired accuracy. To do this set the desiredAccuracy property in CLLocationManager.
I think you will have to live with that. That's how Apple implemented it. Getting a fine grained position takes time, just think about how long any windshield-mounted GPS devices in cars take to fix up their position.
So instead of letting your application wait for a longer time, they provide with what accuracy is available almost immediately, based on cell-towers and WiFi hotspots in the vicinity. Only when there has been a more reliable GPS fix will they call into your app again and let you know.
In the end, it is just a question of where the waiting for the fine-grained position is: In your app, where you have the chance of doing something with the more coarse-grained data you get quickly, or in their framework with no chance for apps to do anything useful in the meantime. I think, letting you decide is the better choice.
Depending on the type of app, you could have a map that automatically zooms in deeper as soon as better position data comes in, draw a smaller circle around the position you are expecting etc. For the end user, nothing's worse than waiting without getting any feedback. So even though this is probably not the answer you would have liked, I advise to make the best of it from a user's perspective.