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I am making a program that uses GPS location preferably from smart phone, laptop works too and compares it to a building, the points you in its general direction. I am making this web application specifically for San Jose State Campus for fun. I have read the other posts about the correlation between decimal places and accuracy and a .11m error will be sufficient. Google maps gives me coordinates to the 6th decimal place, I was wondering if they do indeed follow the standard I have read about here. Here is an example of one of the buildings I will index.

https://maps.google.com/maps?q=%2B38%C2%B0+34%27+24.00%22,+-109%C2%B0+32%27+57.00%22&um=1&ie=UTF-8&sa=N&tab=wl

I will only have an arrow point in the direction of the building and rotate it as the lat/long of the user changes and maybe display the approximate distance from the building. I have yet to learn how to properly use google api to draw the users path and etc and that is why I am asking.

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1 Answer 1

A quick search (using no other than our great search engine god, Google) led me to this site, which further linked me to two articles.

The author summarizes:

D. Potere, Horizontal Positional Accuracy of Google Earth’s High-Resolution Imagery Archive, Sensors 2008, 8, 7973-7981.

This paper is more than five years old and the author used control points derived from satellite imagery. He ended up with a root-mean square error (RMSE) accuracy of 22.8 meters.

S.C. Benker et al., Positional accuracy of the Google Earth terrain model derived from stratigraphic unconformities in the Big Bend region, Texas, USA. Geocarto International 2011, 26, 1–13.

Here the authors find a horizontal position accuracy of 2.64 m RMSE with a mean offset distance being of about 7m w.r.t. a high accurate terrain model.

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Great resources, Paul. I often find it interesting how different the positional accuracy can be looking at the historical imagery in Google Earth of the same location! –  Fezter Aug 19 '13 at 4:53

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