The degree of closeness of measurements of a quantity to that quantity's actual value
37
votes
2answers
17k views
How to measure the accuracy of latitude and longitude?
I am very new to GPS stuff. Suppose I have latitude and longitude as 19.0649070739746 and 73.1308670043945 respectively. So now both co-ordinates are 13 decimal places long. But sometimes, I also get ...
14
votes
1answer
499 views
How accurate is approximating the Earth as sphere?
What level of error do I encounter when approximating the earth as a sphere? Specifically, when dealing with the location of points and, for example, the great circle distances between them.
Are ...
9
votes
3answers
4k views
How does ArcGIS compute the distance between two points with a non-equidistant projection?
This is a follow-up question to my previous one, Can you suggest some well-written introductory texts about coordinate system projections?
Let's assume I'm working with the CH1903 map projection, ...
11
votes
3answers
2k views
What is the maximum Theoretical accuracy of GPS?
I was talking with a potential client, and they requested that we plot some points with GPS, with a maximum (or should that be minimum?) accuracy of 2 m.
This is an area with no WAAS, and I was under ...
17
votes
6answers
1k views
How correct is the “Accuracy” value given by GPS devices?
I have a Garmin Forerunner 305 and a Google Nexus One Android phone. From the GPS on both these devices I can get a "Accuracy" value that is usually between 6-20 meters. How much can I trust this ...
8
votes
1answer
332 views
How much sense does it make to average (lat,lon) samples in order to increase 2D accuracy of a GPS location?
Several GPS applications, like this one, or this one, acquire multiple (lat,lon) samples of a given location, assuming that the GPS unit is not moving, and then take an average of the samples in order ...
12
votes
3answers
452 views
GPS Elephant Tracking: Utilizing A-GPS, WAAS, DGPS and Understanding HDOP, NSAT, and ZDA
*I'm using a GPS data logger (qstarz bt-q1000xt) to track the movement of zoo elephants, and I have a variety of technical questions. I've had limited success receiving answers from the vendor. You ...
