The closeness of a repeated set of observations of the same quantity to one another.

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28 views

QGIS 2.4.0 Chugiak “reduced” real-type numbers. Precision problem? Bug?

I have a SHP point file created from CSV with QGIS 2.4.0 Chugiak. It contains some data on noise in a certain point. When I import from CSV, it seems to be fine, but when I export to SHP and open the ...
0
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0answers
19 views

calculation precision during projection transformation

I am using wgs 84 base tiles, and the tile is not rendered as image but with geojson format. I try to draw them in the tile according to the data. And the geometry of the returned feature is lng and ...
73
votes
3answers
42k 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. In this case both coordinates are 13 decimal places long, but sometimes I also ...
1
vote
1answer
40 views

Unable to select FLOAT precision when adding column

I'm trying to do the lessons in the training-manual at qgis.org. I,m having some problems with 3.3 Ratio Classification ...
5
votes
2answers
504 views

Accuracy vs Precision GPS

I am doing some research on consumer grade GPS accuracy and precision. I took 5 readings for 20 known locations (100 readings). Am I correct in assuming that the standard deviation between the 5 ...
1
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0answers
56 views

Precision for an FGDB raster dataset?

I would like to know the precision for an ArcGIS raster stored within a file geodatabase (FGDBR format); I can't seem to find this information anywhere in their documentation (apologies if I have ...
0
votes
1answer
74 views

How can I change the precision in the attribute table?

I'm working with qgis, v. 2.0.1. I opened a csv-table (from an excel-file) and now the precision is very high but i don't need this. At the moment the values are for example 15.00000000000000, how ...
7
votes
1answer
221 views

What is the precision of SELECT DISTINCT on PostGIS geometry column?

I wonder what the precision of the SELECT DISTINCT operator is on a PostGIS geometry. On my system, the following query gives me a count of 5, which means that the inserted points are considered equal ...
2
votes
1answer
92 views

What is a reasonable time to get a gps fix with 10 meters precision?

I hope I'm asking this at the right part of Stack Exchange. Please bear with me if I'm wrong. I'm developing some gps based applications. The demands I have for precision are not very high, but I ...
5
votes
3answers
279 views

Precision vs Resolution in elevation data

Update: A good example of my confusion: on the Wikipedia page for "digital terrain model" one can find the following statement about a satellite in the "See Also" section: TanDEM-X: generation of ...
2
votes
0answers
127 views

Spatial Precision for Editing in Multiple GIS Clients

I have something I'd like to discuss, I'll try to explain it first, why it's important, and I'll explain how ArcGIS handles the issue, which I think is a good way to handle it. Finally I'd like to ...
4
votes
1answer
208 views

Display XY Format to Shapefile (Scale)

Using ArcView 10.1 and using excel for Lat/Long conversion to a shapefile. The original Lat/Long has 7 numerical characters past the decimal point xx.1143717. When I convert this excel into a ...
0
votes
0answers
31 views

A machine to measure latitude to 6 decimal places of a degree [duplicate]

I am doing a PhD research project to do with medieval and ancient archaeoastronomy which requires me to be able to measure latitudes up to an accuracy of 6 decimal places of a degree of latitude. ...
1
vote
3answers
2k views

How to auto fill or delete sliver polygons without losing precision?

I am developing some boundaries in which precision holds the key value. Using ArcGIS 9.3 I am converting lines to polygons using the "feature to polygon" tool. The lines are accurate but I find ...
2
votes
1answer
62 views

What are arc's guarantees on data precision, XYTolerance (i) when displaying (ii) in arcpy?

Interesting behaviour: Two line segments in a dataset have almost, but not quite, identical endpoints. The difference between them is less than the XYTolerance for the data set. Reading the ...
6
votes
1answer
438 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 ...
5
votes
2answers
4k views

Correct way to create a DEM from point data in csv files

I know this might seem a somewhat general question, but I have to start somewhere. I have a lot of csv files which contain point data containing height, aspect and slope measurements at a resolution ...