I am working on a trails/maps app that has custom trails mapped out in a region and will aid the user navigate his or her way around some trails in a "foresty" area.
Currently, I am using MKMapView to get the user data/location, and loading the trails as overlays from a KML file. The problem I am having is that while testing the app, I noticed that in some situations the blue dot representing the user position goes off the trail overlays, which is expected since GPS (especially on phones) is not that great, plus some error that might have been obtained when getting the values for the trails to put in the KML file.
I apologize if all of that is a bit confusing, my question is: Is it possible to "snap" the user location (the blue dot that we all love) to a trail/overlay/path that is placed on the map with a specific tolerence? for example, if the blue dot appears to be a few pixels off the trails, then it would be placed right in the middle of the trails. If it is far off, then the user probably walked off the trails, and no snapping will happen to the user's location.
First off I wouldn't bother. If they are just a few pixels off they won't care, but if they are further away then it's important that they know where they are as accurately as possible. They could be lost in the snow and looking for trail markings.
If you do go ahead with that you'll have to abandon the userLocation dot and build our own. Using a LocationManager you can get told every time the device gets new location information and move your custom annotation dot to where you think they should be. More trouble that it's worth IMHO.
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I just want some hint of how can I create an app in iOS which can do following.
When a user is at point X, user will click on start button so app will start a timer and track the movement. User will be on a horse and user needs to ride in a full circle. When user comes back to point X the app should draw the route taken by the user on the horse.
Aim is to ride completely in a circle. I want to make this app to
practice and see how close to a circle I ride.
I tried to look at GPS locator but I am not sure whether it will give me efficient results because the circle I ride can be as small as 60m or less in radius.
I don't know if iOS GPS can be this accurate. I read article on motion sensor and how to track rotation and acceleration.
But I am not quite sure how to use that to my advantage.
I just need some tips like which API to use etc.
Using the Standard Positioning Service one can achieve 15 meter
horizontal accuracy 95% of the time. This means that 95% of the time,
the coordinates you read from your GPS receiver display will be within
15 meters of your true position on the earth.
More Information click here
For integrate Map and draw path using current position google map is good option for integrate in iOS mobile .
small and range and get accurate result use indoor position system.
For more information about Indoor positioning system (IPS) click here
http://developer.estimote.com/
and Github iOS demo : get code
I downloaded the Indoor Atlas iPhone SDK and also generated path maps and test paths for my venue. SDK navigates me perfectly when I am moving from one place to another but when I stop moving it generates scattered output with the position radius from 10 to 25. I am expecting precise co-ordinates in both the above cases in my project.
Is there any way to get more precision?
IndoorAtlas technology is using the history of magnetic field observations for computing the precise location. This means that the device needs to move some distance in order to collect enough data to converge to a correct location estimate, i.e., to have a location fix. We are constantly improving our service to decrease the time needed for the first location fix.
If you experience your position moving after you've already stopped walking yourself, please contact support#indooratlas.com with details of your application and venue where this is experienced and we'll look into it. Thanks!
So basically, the scenario is described as thus:
For what I have right now, my application can zone in on the user's location with a blue dot showcasing itself on the iPhone. However, what I'm looking to do is have the application also zoom in onto the user's location close enough that they can see the streets, avenues, etc. that encircle them--but, at the same time, I want my application to "blur out" anything outside of a certain specified radius. So basically, for the latter part, you would be able to see every detail that is in, say, a 5-mile radius of your location clearly, but outside the radius, it would be blurred out.
I sincerely don't know if the latter portion of the above paragraph can be accomplished, but at the very least, can someone help me out on the zooming portion and, if it is possible, the blurring out portion as well? Thank you very much!
I am developing an app that uses the user's location to be displayed on a map with other users.
I want to ensure that all users have a bit of privacy when it comes to their location being displayed openly to other users, so I am hoping to just set their location with a specified offset (lets say 1 mile) and display the "edited" location to all other users while still showing the "exact" location to the current user.
Example - If I am looking at the map, I want my "user location" (the blue dot) to be somewhat exact, while all other player's will see my location slightly offset from the real location.
What is the best way to achieve this?
I think the question you actually want the answer to is this:
How do I convert the user's location into an "approximate location" in a way that preserves the user's privacy?
It's not an easy problem:
Offsetting by a specific distance doesn't work:
There's a trivial attack if the direction is fixed.
If the direction does not change often enough, then the attacker only needs to wait to identify what looks like a road.
If the direction changes too often, then they'll tend to form a 1-mile circle around the target's house/work.
Offsetting by a random distance/direction doesn't work; the attacker just needs to collect enough samples; the clusters will likely be centered on the target's home/work.
Quantizing to a grid naively (e.g. "X is within this grid square") will tell you when the target crosses a grid boundary. This is especially bad if the target lives on a grid boundary.
Here's something that works a little better, but wil still (eventually) give away the user's location:
Pick an (approximately) 1-mile grid. For a "square" grid, you could use the Pierce quincunxal projection (there are four points of infinite distortion but you can make those all at sea — it looks like you can limit distortion on land to a factor of 2). There are also projections onto cube and, for a triangular grid, an icosahedron.
When you first need to report the user's location, give the nearest point on the grid. Also pick a threshold distance between 1 and 2 grid "squares", or so.
While the user is within the threshold distance of the center of the grid square, continue to report the same grid square. Otherwise, repeat.
It'll still eventually be obvious if the user happens to live on a grid boundary. There are various ways to attempt to fix this problem (e.g. a bias to reporting grid squares you've reported before), but these will eventually fail.
This seems a lot like trying to remove a digital watermark (the user's actual location) by using lossy compression (the approximation process) while producing an output image/audio (approximate location) that sounds/looks like the original. (The analogy works a little better if you treat the "watermark" as the user's daily habits, which will be visible in the output unless you know exactly what those habits are and can remove them.)
Or in signal processing terms: A low SNR simply means you have to listen for longer to extract the signal.
Are you showing everyone else as a pin? It might be strange if you show a pin at an exact location but the other user isn't there. For example if someone was a mile north and you showed their pin at the same location as the current user. Maybe you should display the other users with an MKOVerlay circle, and then use some calculation base on a userID to shift it slightly off centre so that people don't find out that it is always shifted 500m east and thus easily see here people are.
Whether or not you change the display, the code you seek is here: Get the GPS coordinate given the current location, bearing and distance
I made a very simple APP in which I can throw a pin right onto the location I am standing at (just a beginner's practice). But I found a problem.
I swear neither I was moving nor the device thought I was moving. And I directly use the geolocation to set the pin. but the pin and the current-location blue point are hundreds of meters apart.
(By the way, the blue point expressed my real location at the time.)
This is a famous problem of Google Map on iOS in China. Put aside the complicated issue of the so-called national security, where I want help is what should we do as a developer. Technically, is there a way, in programming, to figure out what exactly the offset is and correct it?
Does anyone have any idea?
At what time did you place the pin? iOS has up to three sources of location data (cell tower triangulation, Wifi sniffing and GPS) and will keep you up to date with the most accurate. So often you get a not very accurate location, then a more accurate location, then an even more accurate location.
If you have a MKMapView open then something you can do is key-value observe on its userLocation property rather than starting any sort of CLLocationManager. That way you'll always be updated with whatever the map view has decided is the current location, meaning that you don't need to try to match your logic to its.
I did some research on the offset, but haven't gotten a satisfying result yet. The added offset is deterministic, i.e. given a location, the deviated location is fixed. So my goal is to get the deviation function, f(p)=p', where both p and p' are 2D points. You can check here if you are interested.