Corelocation错误的距离 [英] Corelocation incorrect distances

问题描述

我正在开发一个计算用户行进距离的应用程序。我正在使用CLLocationManager类来执行此操作，但我最初获取缓存数据，并且距离变量也以突然的速率增加。请帮帮我......我使用了以下代码....

I am developing an application which computes the distance traveled by the user. I am using CLLocationManager class to do so, but I am getting the cached data initially and also the distance variable is increasing at a sudden rate. Please help me out... I have used the following code....

注意：距离是静态变量。这里

Note:distance is a static var. here

  - (void)viewDidLoad {
    [super viewDidLoad];
//bestEffortAtLocation = nil;
oldLocat = [[CLLocation alloc]init];
newLocat = [[CLLocation alloc]init];
locationManager =[[CLLocationManager alloc]init];
locationManager.delegate = self;
locationManager.distanceFilter =  kCLDistanceFilterNone;
locationManager.desiredAccuracy = kCLLocationAccuracyBest;
[locationManager startUpdatingLocation];

  }

- (void)locationManager:(CLLocationManager *)manager
didUpdateToLocation:(CLLocation *)newLocation
       fromLocation:(CLLocation *)oldLocation{




// test that the horizontal accuracy does not indicate an invalid measurement
if (newLocation.horizontalAccuracy < 0) return;


NSLog(@"accuracy %d",newLocation.horizontalAccuracy);

// test the age of the location measurement to determine if the measurement is cached
// in most cases you will not want to rely on cached measurements
NSTimeInterval locationAge = -[newLocation.timestamp timeIntervalSinceNow];
//NSLog(@"time %d",locationAge);

if (locationAge > 5.0) return;



self.oldLocat = oldLocation;
self.newLocat = newLocation;


double latDegrees = newLocation.coordinate.latitude;
NSString *lat = [NSString stringWithFormat:@"%1.5f°",latDegrees];
latLabel.text = lat;
double longDegrees = newLocation.coordinate.longitude;
NSString *longt = [NSString stringWithFormat:@"%1.5f°",longDegrees];
longLabel.text = longt;
[self computeDistanceFrom:oldLocat tO:newLocat];

   }

    -(void)computeDistanceFrom:(CLLocation *)oldL tO:(CLLocation *)newL
 {
NSLog(@"oldd %@",oldL);
NSLog(@"new %@",newL);


distance = distance + [oldL getDistanceFrom:newL];
NSLog(@"distance %f",distance);

}

控制台显示以下数据..... ..

The console is displaying the following data.......

准确度0 oldd（null）new< +28.62114850，+ 77.37001021> +/- 80.00m
（速度-1.00 mps / course -1.00）@ 2010-06-22 19:21:59 +0530距离
0.000000

accuracy 0 oldd (null) new <+28.62114850, +77.37001021> +/- 80.00m (speed -1.00 mps / course -1.00) @ 2010-06-22 19:21:59 +0530 distance 0.000000

准确度0 oldd< +28.62114850， +77.37001021> +/- 80.00m（速度-1.00
mps / course -1.00）@ 2010-06-22 19:21:59 +0530 new< +28.61670485，
+77.37068155> + / - 80.00米（速度-1.00 mps /航向-1.00）@ 2010-06-22 19:22:00 +0530
距离498.211345

accuracy 0 oldd <+28.62114850, +77.37001021> +/- 80.00m (speed -1.00 mps / course -1.00) @ 2010-06-22 19:21:59 +0530 new <+28.61670485, +77.37068155> +/- 80.00m (speed -1.00 mps / course -1.00) @ 2010-06-22 19:22:00 +0530 distance 498.211345

准确度0 oldd < +28.61670485，+ 77.37068155> +/- 80.00m（速度-1.00
mps / course -1.00）@ 2010-06-22 19:22:00 +0530 new< +28.62112748，
+77.36998540> +/- 80.00m（速度-1.00 mps /航向-1.00）@ 2010-06-22 19:23:02 +0530距离994.432508

accuracy 0 oldd <+28.61670485, +77.37068155> +/- 80.00m (speed -1.00 mps / course -1.00) @ 2010-06-22 19:22:00 +0530 new <+28.62112748, +77.36998540> +/- 80.00m (speed -1.00 mps / course -1.00) @ 2010-06-22 19:23:02 +0530 distance 994.432508

推荐答案

最初获得缓存l是正常的从以前开始。您可以通过查看 timestamp rel =noreferrer> CLLocation 。

It is normal to initially get a cached location from before. You can ignore older cached data by looking at the timestamp of the CLLocation.

您输入的准确度不正确，使用％f而不是％d，输入为double而不是int。

You are printing the accuracy incorrectly, use %f not %d, type is double not int.

GPS首次启动时位置可以快速变化，因为您从单元格三角测量中获得的精度较低，然后当您获得GPS采集时，您将获得更高精度的位置。那些距离很远（1000米），看起来你在几秒钟内移动了很远，但只是准确性发生了变化。

Location can change quickly when GPS first starts because you have a low accuracy location from cell triangulation, then as you get GPS acquisition you get a higher accuracy location. Those can be far apart (1000m) and it appears that you moved far in a few seconds but only the accuracy has changed.

不要使用两个精度差异很大的位置来计算行进距离。

Don't use two locations that have very different accuracy for computing distance traveled.

编辑添加了代码示例，如何忽略旧位置数据。您决定要忽略多久，我在这里使用了60秒：

EDIT Added code sample, how to ignore old location data. You decide how old to ignore, I used 60 seconds here:

- (void)locationManager:(CLLocationManager *)manager 
    didUpdateToLocation:(CLLocation *)newLocation 
           fromLocation:(CLLocation *)oldLocation {

    NSTimeInterval ageInSeconds = -[newLocation.timestamp timeIntervalSinceNow];
    if (ageInSeconds > 60.0) return;   // data is too long ago, don't use it

    // process newLocation
    ...
}

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