甚至PRIORITY_HIGH_ACCURACY也提供了非常低精度的位置更新 [英] Even PRIORITY_HIGH_ACCURACY gives very low accuracy location updates

问题描述

我正在使用FusedLocationAPI获取高精度的位置更新（更新间隔为2秒，最快间隔为5秒）。在大多数情况下，它都能正常工作。但是，有时它可以提供大约1200m的精度。

I'm using FusedLocationAPI to get high accuracy location updates (with 2 second update interval and 5 second fastest interval). It works fine most of the times. But, sometimes it gives accuracy like 1200m.

我知道一开始它可能会发生。但是，我遇到的问题是，我得到了一段时间（大约20m精度）的公平更新，然后突然切换到了大约1200m精度。

I understand that in the beginning it can happen. But, the problem I'm having is, I get fair (~20m accuracy) updates for a while and then suddenly switches to ~1200m accuracy.

这怎么可能发生

推荐答案

有时会发生。此外，错误的定位信息可能会连续5分钟到达。
为了尝试过滤此类坐标，我使用了位置中描述的方法策略文章（请参见保持当前最佳估算值）。

Sometimes it happens. Moreover, erroneous location fixes can arrive for 5 minutes in a row. To try to filter such coordinates, I used the method described in Location Strategies article (see section Maintaining a current best Estimate).

private static final int TWO_MINUTES = 1000 * 60 * 2;

/** Determines whether one Location reading is better than the current Location fix
 * @param location  The new Location that you want to evaluate
 * @param currentBestLocation  The current Location fix, to which you want to compare the new one
 */
protected boolean isBetterLocation(Location location, Location currentBestLocation) {
    if (currentBestLocation == null) {
        // A new location is always better than no location
        return true;
    }

    // Check whether the new location fix is newer or older
    long timeDelta = location.getTime() - currentBestLocation.getTime();
    boolean isSignificantlyNewer = timeDelta > TWO_MINUTES;
    boolean isSignificantlyOlder = timeDelta < -TWO_MINUTES;
    boolean isNewer = timeDelta > 0;

    // If it's been more than two minutes since the current location, use the new location
    // because the user has likely moved
    if (isSignificantlyNewer) {
        return true;
        // If the new location is more than two minutes older, it must be worse
    } else if (isSignificantlyOlder) {
        return false;
    }

    // Check whether the new location fix is more or less accurate
    int accuracyDelta = (int) (location.getAccuracy() - currentBestLocation.getAccuracy());
    boolean isLessAccurate = accuracyDelta > 0;
    boolean isMoreAccurate = accuracyDelta < 0;
    boolean isSignificantlyLessAccurate = accuracyDelta > 200;

    // Check if the old and new location are from the same provider
    boolean isFromSameProvider = isSameProvider(location.getProvider(),
            currentBestLocation.getProvider());

    // Determine location quality using a combination of timeliness and accuracy
    if (isMoreAccurate) {
        return true;
    } else if (isNewer && !isLessAccurate) {
        return true;
    } else if (isNewer && !isSignificantlyLessAccurate && isFromSameProvider) {
        return true;
    }
    return false;
}

/** Checks whether two providers are the same */
private boolean isSameProvider(String provider1, String provider2) {
    if (provider1 == null) {
        return provider2 == null;
    }
    return provider1.equals(provider2);
}

它设计用于标准的Android Location API，但是可以使用。我只是对其进行了一些更正，因为所有修复程序都具有相同的提供程序。它使我可以过滤掉大约30％的错误定位信息。

It was designed for the use with a standard Android Location API, but it works. I just made a few corrections to it, because all fixes have the same provider. It allows me to filter about 30% of "bad" location fixes.

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