The degree of closeness of measurements of a quantity to that quantity's actual value
0
votes
0answers
24 views
Best handheld GPS unit under $500? [duplicate]
I hope this is okay to post here.
I want to do some data collection in my free time which will be hosted on my own website for people to freely download and use.
I obviously want the data to be as ...
4
votes
1answer
75 views
GPS Elephant Tracking II: Is ArcGIS basemap imagery orthorectified?
-- For my original question and pictures of elephants wearing GPS equipped anklets, go here. --
I'm experimenting with the use of GPS anklets to track the movement of zoo elephants. This has proved ...
3
votes
2answers
146 views
How to get the best accuracy of coordinates for web GIS- application?
I would like to get advice from you about one thing. I would like to develop my own web GIS application. It would be about some sport places in my hometown; it would be good practice for my education ...
11
votes
3answers
1k 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 ...
0
votes
0answers
50 views
How accurate is spherical geodesic distance? [duplicate]
Possible Duplicate:
Approximating earth as sphere
We are in a situation where spherical distance computations may be more convenient and faster than ellipsoidal ones. However, I am ...
3
votes
1answer
82 views
CORINE LandCover: what about the accuracy?
How accurate is CLC? Do anyone know any scientific papers about that question? I tested the new CLC2006 for a region in turkey and its totally rubbish!
12
votes
2answers
456 views
ArcGIS Buffer accuracy problem
world,
once again I encounter something very strange with ArcGIS. I perform a buffer analysis on one side of a polyline. There seems to be a serious accuracy problem and I can't figure out what the ...
2
votes
1answer
184 views
How do you calculate positional accuracy in qgis?
How to you compare two layers in QGIS to get the positional accuracy?
5
votes
1answer
254 views
Need to learn more about Precision and Accuracy
I am currently taking Introduction to Image Interpretation online and there is a section in it that talks about Precision and Accuracy. I wanted to know if someone out there has any good information ...
8
votes
1answer
329 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 ...
14
votes
1answer
493 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 ...
4
votes
1answer
315 views
Probability of iOS/Android device location accuracy
I'm working with Android and iOS apps that report location. Both iOS and Android can derive location from a combination of cell tower triangulation, visible wifi access points, and assisted GPS. The ...
19
votes
2answers
340 views
Precision when working with spatial data in GIS
Is there a basic or introductory study that examines and compares the precision of spatial data when working
with varying precison of the data input, like having 1, 2, ... decimal places?
with the ...
24
votes
11answers
10k views
Tablet or smart phone GPS vs “real” GPS
I've been reading a lot today about android and iphone devices being used for spatial data collection in the field and it sure seems to be that single purpose devices such as the extremely popular ...
4
votes
1answer
194 views
Does a geotagged image contain information about its accuracy?
When i view my current location on Google maps on my android it shows me a circle of uncertainty. If i take a geotagged picture it will off course contain information about its Lat or Lon. Does it ...
4
votes
1answer
323 views
Which interpolation method is the most suitable for DEMs?
Which interpolation method is the best suitable for hill/valley areas and normal ground with undulations and rivers? When working with Aster 30mX30m DEMs, which method will give the most realistic ...
3
votes
0answers
157 views
Equipotential Surface Generation Using Monte Carlo Simulation on Large Raster Images
All,
I have a large (1GB+) raster that I am using as the base for the generation of an equipotential surface. This is to assess the accuracy of DEMs derived from another source. In situ ...
12
votes
3answers
449 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 ...
2
votes
1answer
728 views
how to calculate RMS 2D and RMS 1D, using python?
I would like to calculate:
RMS 2D: standard deviation for the two coordinates of flat (67% confidence level)
and
RMS 1D: standard deviation for height (67% confidence level)
What is the formula and ...
4
votes
4answers
203 views
Is city-supplied GIS data sufficient for transit operators or do they need their own set of GIS data?
City GIS data is usually built in a format where streets/avenues/boulevards/etc are modeled as lines that are geographically located in the middle of the streets/avenues/boulevards/etc. Is that ...
6
votes
1answer
171 views
Accuracy of planimetric geometry vs. ellipsoidal model
I'm examining the two geospatial options for IBM's DB2 database. In particular I am interested in the accuracy between these two options and whether it's worth it (the more accurate representation ...
6
votes
2answers
2k views
How accurate are measurements in Google Earth?
Can anyone point to a resource that lists the accuracy of measurements taken in Google Earth?
4
votes
3answers
3k views
Generally accepted root mean square (RMS) error for rectifying topographic maps
This is a generic inquiry on the common practice/standard for determining the acceptable values of RMS when georeferencing topographic maps. Is there an absolute value?
Some literature suggests that ...
37
votes
2answers
16k 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 ...
24
votes
6answers
724 views
How to cope with the newly discovered GPS bug? [closed]
Today the New York Times broke the news that after the Clinton Administration turned off Selective Availability in the GPS system, a bug had been introduced into the GPS satellite software itself, ...
4
votes
2answers
240 views
Is there a way to distinguish data precision in KML?
Here's my problem (and I was inspired to ask this from this question)...
I create a KML file recording where upcoming training courses will be for the next year. The cities might be Atlanta, Calgary, ...
3
votes
1answer
107 views
What sample size should be used when applying the National Standard Spatial Data Accuracy (NSSDA)?
I'm less interested in what is recommended by FGDC, and more interested in information like this: SAMPLE SIZE AND CONFIDENCE WHEN APPLYING THE NSSDA, which suggests you need a sample of 100. Is there ...
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 ...
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, ...
17
votes
6answers
1k views
Is GPS more accurate on specific hours of the day?
I have heard that the GPS system is more accurate, and less accurate on some specific hours on the day.
If this is true, how can I get the information on when GPS is more or less accurate at my ...
