CODEWITHSUNDEEP
google-mapsgeolocationgoogle-street-view
Kotaro
Kotaro

Reputation: 481

How accurate is the Lat/Lng that you get from SV API's getPosition()?

I am asking the same question on Google's product forum, so excuse me if you see the same question.

A screenshot of a Google Street View Service example

I am using Street View Service to develop my application that is similar to this example (figure above). In this application, I want to store where, in lat/lng coordinates, users have traveled on the map. I figured out StreetViewPanorama class provides an API, getPosition(), and this returns LatLng. Lat/lng coordinates you extract from LatLng object look like lat=38.924066 and lng=-77.032172. I can use these values to store what I want.

Although the aforementioned latlng values have 8 significant figures, I was actually wondering how accurate these values are, because GPS locations that Google collects while running a Street View car would have errors.

So my question is, how accurate is the latlng value returned by getPosition()? In other words, how much concordance can I expect between latlng values from getPosition() and latlng position on Google Map?

Thank you very much!

Upvotes: 0

Views: 5109

Answers (2)

Larry Ricker
Larry Ricker

Reputation: 11

As indicated in the above answer, the real limitation is the positioning of the map, not the numerical value obtained from it.

For example, I happened to be taking readings at a location where two Google Map sections overlapped. There was an obvious discontinuity in color and terrain features when going from one to the other. The photos must have been taken at least a year apart.

A marker placed on one side of this overlap jumped by at least 10 m when viewed on the other overlapping section. In other words, one (or both) map sections were off by at least a few meters relative to the true GPS coordinates.

If you are lucky enough to be working on a single section, distances between map points are probably quite accurate, but if you check a point against the actual GPS coordinate on the ground, who knows? A bias error of 6-30m seems likely to me.

Upvotes: 1

Kotaro
Kotaro

Reputation: 481

I got an answer in another forum so I copy it over here too and mark the question as solved. The following is the answer from barryhunter in Google Forum.

A 6dp lat/long is on the order of precise to 0.1m. (ie 10cm)

So such a lat/long should match up very precisely with the Google Map. Ie its a precise location.

But as to how accurate the underlying map is, that varies a lot. Its almost impossible to tell. Most locations I would estimate to be within about 6-30m

You can check the accuracy of a lat or a lng value with 6 decimal points in the following page: http://nearby.org.uk/precision-ll.cgi?lat=38.924066&long=-77.032172

Upvotes: 1

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