The degree of closeness of measurements of a quantity to that quantity's actual value

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2
votes
1answer
31 views

Relationship between contour interval and spatial resolution of a generated DEM

If I have contour lines with interval say 10, 5, or 2 (etc.), and I generated a DEM from them, what is the relationship between between the contour interval and the resolution of the DEM? Irrespective ...
0
votes
1answer
28 views

Accuracy of GPS and HDOP

Given a handheld GPS with an accuracy of roughly 2 meters (verified through field tests) and an observation with an HDOP of 1.2, the accuracy of that one observation should be within 2 meters X 1.2 of ...
1
vote
1answer
28 views

Transfer from Android phone to Windows OS truncates lat long

I am clicking GPS enabled pictures of sites which are less than 500 metres apart through Android based Samsung ACE Duos phone. I later use Google Earth on my Laptop to view these geo tagged pictures. ...
0
votes
0answers
42 views

ODK Collect GPS Accuracy

Good day. Is it possible to require a minimum accuracy of the GPS widget? I know about accuracy threshold but what I need is to prevent forward swiping/finalization of the form if GPS accuracy is low. ...
1
vote
1answer
54 views

Is this distribution of GPS positions caused by multipath distortion?

I have some GPS points that are close to where they should be, but not nearly close enough (horizontal precision is around 10 meters). Looking at the positions which comprise these points (there are ...
2
votes
0answers
40 views

How to measure RTK accuracy of a moving vehicle?

I am currently working with tractors using a RTK enhanced automated steering system. One of the biggest problems is that even RTK can have a inaccuracy of 2cm. This can be too much for some possible ...
0
votes
0answers
47 views

How to randomly generate 3 X 3 pixel window/grid size in ArcMap?

I have a raster image in ArcMap and I want to assess the accuracy of my raster image with a reference image. So, I need to randomly generate a bunch of (i.e 50) 3 X 3 pixel window/grid size from my ...
1
vote
0answers
151 views

Collector for ArcGIS PDOP and GPS collection configuration settings

My company just acquired a Geneq SXBlue II GPS receiver to pair with an iPad and the Collector for ArcGIS app. The functionality is awesome and loved by everyone, but since we have biologists on our ...
0
votes
0answers
28 views

Objective comparison of different land cover data sets

One of the answers in this question Equivalent of CORINE land cover data sets for rest of world mentions the difficulty of comparing different land cover data sets such as CORINE and Global Land ...
1
vote
0answers
43 views

How to select random objects in eCognition?

I classified a Landsat image in eCognition and now I want to select random objects so that I can compare their class to ground-truth data and perform the accuracy assessment. How can I do this in ...
1
vote
1answer
41 views

Why does the undefined “ghost classes” arise during supervised classification in ERDAS IMAGINE?

After a supervised classification in ERDAS IMAGINE I have some undefined "ghost classes" in the attribute table. Also have a look at this youtube video at about 7:12. I'm wondering why they arise and ...
0
votes
1answer
68 views

Benefit of DGPS for relative accuracy and speed measurements for receivers close-by each other

Consider that we are interested only in the speed and relative position accuracy of GPS receivers (i.e. their absolute try position on earth is NOT important). These receivers are all in a 90m x 90m ...
3
votes
2answers
96 views

Accuracy assessment using polygons as reference data as against point data?

Is it possible to do accuracy assessment using polygons as reference data as against point data? I have field-identified polygons as data for training and reference (from a forest-agri mosaic) that ...
3
votes
2answers
58 views

Compensating lat/long offsets after conversions

In my application I am doing conversions between two different formats of data. First format is a simple one containing NE and SW coordinates for a given rectangular area: area = { "sw": { ...
1
vote
2answers
106 views

Worldwide High-Resolution Water Body Shapefiles with Consistent Scale

Where from your website can I access worldwide vector water body shapefiles that have better resolution than the generic SRTM 90m data? Do you have coastlines and inland features (lakes, estuaries, ...
0
votes
0answers
89 views

ERDAS file not recognized as ERDAS Hierarchal File Architecture (EFHA)?

I am trying to do an accuracy assessment in Erdas using "user defined ground control points" (I collected the GPS points myselfin the field using a handheld GPS). However, when I load the thematic ...
1
vote
1answer
85 views

How do I preserve measurement between QGIS and Google Earth?

Wondering if anyone has found a way around this: I am having issues when importing shp files into Google Earth. I need reasonably accurate measurement data and my measurements change significantly ...
3
votes
1answer
250 views

Standard Terminology for User's and Producer's Accuracy

In the literature I see terms such as, User's accuracy Pr( Y = c | X = c); Producer's accuracy Pr( X = c | Y = c); where X is the estimator of a particular land use, Y is the random variable ...
3
votes
2answers
211 views

Removing incorrect (non-ground) points from LiDAR data? [duplicate]

I have ground lidar points, nonground lidar points and tree lidar points. The problem is some of the ground lidar points are incorrect. For example, the highest elevation values of tree and building ...
2
votes
1answer
444 views

How is Precise Point Positioning (PPP) exactly done?

I am looking for a positioning accuracy that is higher than normal consumer-grade GNSS receiver (mostly GPS/GLONASS hybrids with +- 5m precision). I came across RTK with dual receiver setup (base ...
6
votes
1answer
2k views

Cheapest centimeter accurate satellite positioning (GNSS/GPS)

I am looking for a cheapest possible GNSS/GPS setup with a centimeter precision without much HW hacking. I am not able to produce my PCB or do any soldering (though I would do that if there is no ...
8
votes
2answers
134 views

What is a good metric for mapping accuracy

I have recently received a dataset that supposedly mapped the altitude a given region (a DEM). I would like to determine the accuracy of the new map by comparing it with a previously generated DEM. ...
1
vote
0answers
1k views

Translating hdop, pdop and vdop to metric accuracy from given NMEA strings

How can I translate dilution of precision to a metric unit? For example: say I got 1.2 in hdop from NMEA sentence of my GPS receiver, in what should I multiply to get a metric accuracy? Just like the ...
3
votes
2answers
445 views

How are kappa and overall accuracy related with respect to thematic raster data?

I recently calculated kappa (using confusionMatrix{caret} in R) between a thematic raster dataset at 1m spatial resolution and another at 30m spatial resolution. I was interested in quantifying the ...
1
vote
0answers
53 views

Question about projected coordinate systems 30m DEM for Contiguous US

What is the best Projected Coordinate System (PCS) for the contiguous US (whole, not parts) if I want to maintain distance and area accuracy as much as possible across a nationwide DEM dataset? I'm ...
2
votes
1answer
206 views

Accuracy issues between data in QGIS and Google Earth

Wondering if anyone can answer this question. I have a kml in Google Earth. When I import it to QGIS, and then import the Google Earth images they are in slightly different places. I used a QGIS ...
5
votes
0answers
182 views

How to compare two sets of points in QGIS?

I have two point layers with XYZ data; one set are points measured in the field and the second set is a Lidar data set. I want to check the accuracy of the Lidar in comparison to the measured data. ...
4
votes
1answer
194 views

If the GPS navigation message takes 12 1/2 minutes to cycle, how can receivers update your position every second?

According to Wikipedia's article on GPS, Each GPS satellite continuously broadcasts a navigation message... Each complete message takes 750 seconds (12 1/2 minutes) to complete. My ...
0
votes
1answer
204 views

Clip a shapefile based on raster extent with high accuracy

I am trying to clip a shapefile based on the extents of a smaller raster. I find the extent of the raster using this code: Extents = arcpy.sa.Raster(MyRaster).extent` Then, I use these lines to ...
3
votes
2answers
242 views

Map accuracy assessment by moving window in R

I would like to make an accuracy assessment using a confusion matrix between classified Landsat image and reference dataset. Maps have the same resolution and extent. I would like to evaluate the ...
1
vote
1answer
100 views

What sub-meter geolocation solutions exist and how can I integrate them into a web and mobile mapping workflow?

I am the manager of seven water systems. What I am trying to do is map out every meter and valve on to a map and then my workers can have the maps on their iPhones so when they have to go fix a water ...
5
votes
2answers
768 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
vote
2answers
353 views

Canada FSALDU 6-digit Postal Code Data Providers

I have been looking into finding point data for the Canadian 6-digit postal code (FSALDU). I have come up with 3 sources so far, 2 being far more expensive than the other. After speaking with the ...
2
votes
2answers
2k views

What class/types of smartphone chipsets support GPS, A-GPS, GLONASS AND have extended kalman filtering?

I've been testing several Android phones (all running Android 4+) Sony Xperia T, Moto G, Nexus and HTC 1 which are all giving decent tracks (all of which use GPS/GLONASS) However we are also using ...
2
votes
1answer
548 views

Google earth, google satellite and bing aerial accuracy

Does anybody know what is the accuracy on Google earth, google satellite and bing aerial and on what scale.I think that you have different-better accuracy if you have subscribed to their professional ...
5
votes
1answer
803 views

What is required for post-processing differential correction? (And can Garmin units provide it?)

2 very closely related questions about differential correction with a Garmin unit: 1). Some data was collected using a Garmin GPSMAP 76Cx unit and the data collectors are interested in whether ...
2
votes
0answers
51 views

Is there any statistical method to proof if the method is suitable or not [closed]

I have recently done a phenological study using threshold method from MODIS NDVI images. But I'm suffered that I don't have any situ observation (ground truth) data to do validation. Is there any ...
2
votes
1answer
344 views

Is there any information in Sky Plot that is not in DOPs chart in terms of predicting accuracy in the field? (GPS data collection planning)

Joe only looks at DOPs chart and weather report for mission planning. Moe looks at both DOPs chart and Sky Plot and weather report. Is Joe missing out on something relative to Moe in terms of ...
2
votes
1answer
86 views

resampled thematic map accuracy

I've generated a map of ecoregions based on some environmental data using a semi-supervised classification where I combined a statistical clustering with random forests to generate my map. I created ...
1
vote
1answer
261 views

How geographically accurate is Google Earth?

I'm using a KML file which I have loaded in to Google Earth. I am looking at some islands, and see items such as the following island: Note the blue region is the polygon describing the area ...
2
votes
1answer
115 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 ...
1
vote
0answers
284 views

How to use QGIS Accuracy Assessment plugin? [closed]

I am new user and i want perform accuracy assessment in qgis. I have 1 classified map and another for validation. I have installed the plugin. what am i doing after? Plugin: ...
5
votes
2answers
189 views

Spatial interpolation - appropriate method to estimate the accuracy of the surface

When using a spatial interpolation method (any method) without having a way to validate it, besides sampling some points out, is there a way to count as well with the mean distance between ...
2
votes
1answer
4k views

How accurate is the google maps latitude and longitude I am using?

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 ...
4
votes
1answer
208 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
280 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 ...
17
votes
4answers
20k 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 ...
3
votes
1answer
190 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!
13
votes
2answers
831 views

ArcGIS Buffer accuracy problem?

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 cause is. ...
2
votes
1answer
373 views

How do you calculate positional accuracy in qgis?

How to you compare two layers in QGIS to get the positional accuracy?