I'm writing a running app according to an online tutorial on http://www.raywenderlich.com/97944/make-app-like-runkeeper-swift-part-1.
In the tutorial,the distance the user has run since the start is calculated from two latest recorded locations using "distanceFromLocation" method in CLLocation. However in CMPedometer there's also a distance data which can be retrieved directly. So which one should I use and why?
Thanks
CMPedometer relies on the motion tracking chips built into modern iPhones to measure steps and distance travelled by the owner of the device. It is able to estimate the number of steps taken using motion data, and extrapolate the distance traveled by the user using step counts and estimated stride length. If a distance estimate is good enough for your purposes, then CMPedometer is an easy, power efficient solution to tracking distance travelled.
On the other hand, if you would like the reported distance to be as accurate as possible, you should use CLLocation and calculate the distance between each location the user travels through on their workout. This requires more complex code and an accurate GPS signal. As an added benefit, you'll be able to use the location data to, for instance, draw a map of where the user ran on their workout.
Related
I am sorry if this has been asked in one way shape or another. I have started working with beacons, and in Xcode (Swift) - using CoreLocation. I really need a more accurate determination between the device and a beacon though. So far I have been using the standard proximity region values (Far, Near, and Immediate), however this just isn't cutting it at all. It seems far too unstable for the solution I am looking for - which is a simple one at best.
My scenario;
I need to display notifications, adverts, images etc to the users device when they are approximately 4 meters away from the beacon. This sounds simple enough, but when I found out that the only real solutions there are for beacons are those aforementioned proximity regions, I started to get worried because I need to only display to devices that are 3-5 meters away, no more.
I am aware of the accuracy property of the CLBeacon class, however Apple state it should not be used for accurate positioning of beacons, which I believe is what I am trying to achieve.
Is there a solution to this? Any help is appreciated!
Thanks,
Olly
There are limitations of physics when it comes to estimating distance with Bluetooth radio signals. Radio noise, signal reflections, and obstructions all affect the ability to estimate distance based on radio signal strength. It's OK to use beacons for estimating distance, but you must set your expectations appropriately.
Apple's algorithms in CoreLocation take a running average of the measured signal strength over 20 seconds or so, then come up with a distance estimate in meters that is put into the CLBeacon accuracy field. The results of this field are then used to come up with the proximity field. (0.5 meters or less means immediate, 0.5-3 meters means near, etc.)
When Apple recommends against using the accuracy field, it is simply trying to protect you against unrealistic expectations. This will never be an exact estimate in meters. Best results will come with a phone out of a pocket, with no obstructions between the beacon and the phone, and the phone relatively stationary. Under best conditions, you might expect to get distance estimates of +/- 1 meter at close distances of 3 meters or less. The further you get away, the more variation you will see.
You have to decide if this is good enough for your use case. If you can control the beacons there are a few things you can do to make the results as good as possible:
Turn the beacon transmitter power setting up as high as possible. This gives you a higher signal to noise ratio, hence better distance estimates.
Turn the advertising rate up as high as possible. This gives you more statistical samples, hence better distance estimates.
Place your beacons in locations where there will be as few obstructions as possible.
Always calibrate your beacon after making the changes like above. Calibration involves measuring the signal level at 1 meter and storing this as a calibration constant inside the beacon. Consult your beacon manufacturer instructions for details of how to do this calibration.
I need to implement a auto-check in feature for managing office attendance.Will accuracy of geofencing be effected if office is situated on 50th floor.ie Does altitude variance effects accuracy of geofencing?
The accuracy is not an issue (geofencing is based on lat/long coordinates, which are the same regardless of the floor). The issue is going to be GPS accuracy. Due to the fact that GPS is not able to penetrate walls, the GPS coordinates will nearly always show you outside of the building, not inside of it. Not to mention being able to identify which office room someone has entered.
If this is acceptable accuracy level for your project, then just GPS works. If you need to see that the person has actually entered the building or the specific office, you will need to utilize beacons.
(Disclosure: I work for Proximi.io, a technology-agnostic positioning platform)
i am doing one application.In that I want to find how much distance travelled by user.And i don't want to use the GPS due to battery drain.In some posts i saw,they are using Accelerometer to find the distance with different formulae.But didn't understand that posts.And that accelerometer giving the accelerate data when the device is in stationary mode also.So how to calculate the distance travelled by user.
I am using an iBeacon, and using triangulation and trilateration (or something similar), want to be able to locate an exact (or fairly accurate) distance between the iBeacon and user's device (in feet/metres/e.t.c). What is the best way to do this, and how would I do this?
I forgot to mention: I understand that it is possible to find proximity (i.e near, immediate, far, etc.), however as mentioned, ideally I am looking to find an accurate distance (maybe by combining RSSI, accuracy, and proximity values).
For this you should use RSSI (Received Signal Strength Indication) of an iBeacon. The signal strength determines how close or far it is from you. But the problem is that:
Every beacon's RSSI might differ distance, accuracy.
If beacon is behind the wall or any static obstacle the RSSI-Distance-Ratio will not work.
Therefore instead of Triangulation or Trilateration you should go for Fingerprinting. This will work better then rest of the techniques.
Place obstacles all around you.
Make reference points on your map.
Calibrate your app with that location i.e. Get the signal strengths from atleast 3 nearest iBeacons and save it against that reference points.
Do this for all other reference points.
(If you can) Do this twice or thrice and take average and store in database.
Now you have laid map of calibrated reference points. (This will handle all different RSSI-DIstance-Ratios of all the beacons)
Now whenever you are at any position compare it with the nearest point and you will get to know the closest location of your reference point.
If you are using google maps, the lat long they provide is upto six decimal place i.e. 0.11 meters which i think is preety much accurate in a room as well.
I guess this helps :)
Please mark this the right answer if it works.
In iOS the Core Location beacon information you get when you range a beacon includes both a "proximity" value (far/near/immediate) and an "accuracy" reading, which is actually approximate distance, in meters.
In order for the distance reading to be as accurate as possible, you should really calibrate your beacons. To do that, you put the beacon exactly 1 meter from the receiver and take a reading. The receiver gives you a "measured power" reading, which you then set on the transmitter. The measured power reading is used in calculating the distance reading.
Distance readings are very approximate, and are subject to interference from the surroundings.
The Apple sample app "AirLocate" shows working code for calibrating a beacon, and I believe it also displays
I'm looking to create a function for my app which records the distance travelled in the vertical plane. More specifically, I want to record how far the device has been 'dropped' - this could mean dropped at arm's length onto the floor or dropped slowly with the user as they go down ten floors in an elevator. I'm looking for advice on the best way to calculate this with a relatively high level of accuracy.
I've read a little on the difficulty in accurately measuring distance travelled using core motion - especially as I need it to work even if the device rotates during the movement. From what I've researched it seems as though it would be impossible, or at least very difficult, to achieve this using core motion.
Would I be able to achieve this effect with Core Location instead? I've seen posts about calculating lateral distance, as in during a car journey, but nothing about vertical distance.
Is it as simple as 'startingAltitude - endingAltitude = distanceTravelled?
If so - how accurate is the altitude measurement of Core Location and how could I get started with this behaviour? I'm fairly new to iOS programming and would appreciate any pointers on the most appropriate method of achieving the function I want.
Thanks
There are serious limitations to both approaches.
Using an accelerometer to measure distance travelled requires very precise and accurate real-time measurement of acceleration. Any error in acceleration reading leads to error in your velocity calculation, which makes your location reading drift from the real location. Drift gets worse over time, to the point where the error swamps the actual location reading.
Based on my testing the altitude reading in iOS GPS devices is really bad. +/- 100 or more meters is not uncommon. Indoors GPS readings tend to get really bad, and the altitude reading is bad enough to start.