horizontalAccuracy究竟意味着什么？ [英] What does horizontalAccuracy exactly mean?
问题描述
我正在使用位置服务开发iOS应用程序。拥有实验物理学的背景，我想知道在中的代表。文档有点稀疏...... 位置中究竟是 horizontalAccuracy locationManager：didUpdateToLocation：fromLocation：
I am working on an iOS application using location services. Having a background in experimental physics, I am wondering what exactly horizontalAccuracy in a location found in locationManager:didUpdateToLocation:fromLocation: stands for. The documentation is a bit sparse...
我假设精度给出了基于高斯（或泊松？）分布的置信区间。因此，在一定概率下，实际位置在半径为 horizontalAccuracy 的圆内，但也可能在该区域之外。那么问题是：这个概率有多大？如果 horizontalAccuracy 对应1σ，我有可能在68％的范围内使用 horizontalAccuracy ，但另一方面，在近三分之一的情况下，实际位置将在该区域之外。因此，在某些情况下，我宁愿使用2σ （ 2 * horizontalAccuracy ）甚至3σ （ 3 * horizontalAccuracy ）用来计算。
I assume that the accuracy gives a confidence interval based on a gaussian (or poisson?) distribution. Thus, with a certain probability, the actual position is within a circle with a radius of horizontalAccuracy, but could as well be outside that area. The question is then: how big is that probability? If horizontalAccuracy corresponds to 1σ, I'd have a probability of 68% to be within that circle with horizontalAccuracy, but looking the other way around, in nearly one third of the cases, the actual position will be outside that area. Thus, in certain cases, I'd rather use 2σ (2*horizontalAccuracy) or even 3σ (3*horizontalAccuracy) to calculate with.
简而言之：在某处有任何迹象，有信心interval horizontalAccuracy 有吗？
To put it short: is there any indication somewhere, which confidence interval horizontalAccuracy has?
评论所有回复Apple说它在哪里的人：
嗯 - 测量结果不准确。它必须具有一定程度的不确定性。如果您经常重复测量，您将获得结果分布 - 可能是高斯分布。该高斯具有一定的宽度，其对应于测量的不确定性水平。更频繁地测量位置将减少不确定性，从而提高准确性，但永远不会给你一个明确的间隔，保证实际位置。你只会得到一个概率。但如果准确度是3sigma，我们有99.7％ - 这是接近确定的。
简而言之 - 我怀疑Apple的文档。
Comment to all who respond "Apple says it is within": Well - the measurement can not be exact. It must have a certain level of uncertainty. If you repeat the measurement very often, you will get a distribution of results - probably a gaussian distribution. This gaussian has a certain width, which corresponds to the level of uncertainty of the measurements. Measuring the position more often will reduce the uncertainty and thus increase accuracy, but never will give you a distinct interval where the actual position is guaranteed to be in. You will only get a probability. But if the accuracy is 3sigma, we have 99,7% - which is close to certain. To put it short - I doubt the documentation from Apple.
推荐答案
我一直在寻找相同的信息和找不到任何答案。我唯一的指针是，在Android上，他们使用1σ：
I have been looking for the same information and could not find any answers. The only pointer I have, is that on Android, they are using 1σ:
http://developer.android.com/reference/android/location/Location.html#getAccuracy%28%29
对于所有非信徒，这个链接也解释了准确性如何发挥作用。
To all the non-believers, this link also explains a little bit how the accuracy thing works.
我的猜测是在iOS上也是如此，但没有办法确定 - 除了询问编写代码的人;）
My guess is, the same is true on iOS, but there is no way to be sure - except for asking the guy who wrote the code ;)
编辑：
经过一些游戏并检查位置更新与物理位置之后，似乎在iOS上更有可能是3σ。有两个观察结果让我相信这是真的：
After some playing around and checking location updates vs. physical location it seems like it is more likely 3σ on iOS. There are two observations that lead me to believe that is true:
- 在来自WiFi三角测量的Android位置通常被报告为具有准确性在20到50米之间。在iOS上，它介于65到165米之间。
- 当测量报告位置与设备物理位置之间的距离时，到目前为止，它一直在报告的精度范围内。
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