# Tag Info

Accepted

### Is there a common method for measuring "curviness" of a line?

One measure is Sinuosity which is the line length divided by the shortest distance from the line start and end points: select id, st_length(geom)/st_distance(st_startpoint(geom), st_endpoint(...
• 71.2k
Accepted

### When do permanent RTK base stations need to update their advertised ECEF coordinates to account for continental drift?

In the absence of anyone providing an independent answer, I have researched this topic in much more detail. I believe I now have a good understanding of the issue, and the answer is sufficiently ...
• 191

### Making the coordinate trace looks more smooth without road network

Identify the point exactly in the middle of the two building polygons: Find the two closest polygon to each point and get the point on these polygons closest to the initial point. Connect these two ...
• 70.4k

### Direction of taken photo (QFIELD)

It is possible to store the EXIF data using Qfield. You just need to configure a QGIS expression using the function exif(path, [tag]) Where path is an image file path and tag is the tag to return. For ...

### Use QGIS or QField with a GPS physically walk a polygon in the field

Tracking your route and turning it into a point, line or polygon is possible in QField and is described in the QField documentation how-to guide. To activate tracking you must first activate ...
• 131

### Making the coordinate trace looks more smooth without road network

Create a regular polygon grid with cell distance a bit smaller than the distance between the buildings (see screenshot). Check for each point within which cell it is and snap the point to the cell's ...
• 70.4k

### How to extract the GPS data of the markers that I added in my shapefile in QGIS?

No, those points were added a markers to a line feature. In QGIS you can create points along the line geometry. See this tutorial for generating points along a line. To duplicate the markers as ...
• 9,624

### Apparent movement in stationary GPS

Here's my next answer since the question appears to have changed. I've done a lot wof work with u-blox (including M8-N) - they ALWAYS show the wander from your original question. Unless you change ...
• 704

### Apparent movement in stationary GPS

If the GNSS calculated every position based only on the measurements it had taken over the last second (or 100 milliseconds for 10Hz positioning, etc) and therefore independent of previous positions, ...
• 704
Accepted

### Android GPS accuracy (2 m) is greater than nominal accuracy

tl;dr - Don't trust the "estimated accuracy" value that most GPS apps show you. It's just an estimate coming from the device manufacturer hardware. The best way to assess accuracy is to find ...
• 1,605

### Is there a common method for measuring "curviness" of a line?

I'm not sure if this will be of great use to you, it might be too specific, but I have a function that tests for what I call cutbacks in lines. This is where a line bends more than a certain amount ...
• 7,485

### Average stationary position with GPS

Today there are a range of free RTK correction streams such as http://rtk2go.com . Depending on where you are in the world, you may be able to use these to survey in your base station (as an RTK ...
• 191
1 vote

### Viewing GPS coordinates on Trimble Geoxh 6000

Since you are talking about a Trimble Total Station, I would argue this is more of a Surveying question than GIS due to software. Luckily, I'm educated in both. One of Trimble's proprietary data ...
• 26
1 vote

### Get Lat,Lon,Elevation, and IMU data for DSLR camera

The Open Camera application for Android devices will record the location, elevation, and pitch, roll, and yaw and record those data to the image EXIF data. Of course, the elevation values will be ...
• 9,624
1 vote
Accepted

### How to calculate GPS offset given azimuth(bearing) angle and slope distance and inclination angle of the object

Since distances are small you can simplify the calculation. Use the following as the basis for the calculation: At the equator, 1 minute of Latitude = 1 minute of Longitude = 1 Nautical Mile = 1852 M,...
• 704
1 vote

### Performance of RTK when observed satellites don’t correspond

From my own testing, I've observed that an L1/L2 rover is considerably more accurate with just L1 corrective data (no L2 data) than without any corrections, and that it is also much better than with ...
• 191
1 vote

### Get altitude over WGS84 ellipsoid from GPS tracking app

It is unlikely that the WGS84 ellipsoid heights would be identical to an orthometric or tidal vertical datum height for your area of interest (but that is possible). Here in the USA we have access to ...
• 9,624
1 vote

### Explanation for the GPS “special message” field

The only other reference I've ever seen is in the RTCM spec and this just describes it as a null terminated 90 character ASCII field, with parity. The example is "HELLO". I have not see ...
• 191
1 vote
Accepted

### Does multi-frequency GPS help during cloudy/overcast skies?

As I understand, satellite signal (for GPS) do penetrate through the clouds with no issues. GPS signal can go through weather conditions. More reading is available from this site:http://gpsinformation....
• 2,776
1 vote
Accepted

### Use QField with Bad Elf device/external GPS/specify GPS

Yes. Settings, positioning tab, then hit add button shown in image below.
• 1,826
1 vote

### Making the coordinate trace looks more smooth without road network

Connect the points, e.g. using points to path. Then simplify (generalize) the line, either using A. Menu Processing > Toolbox > Simplify or B. QGIS expressions with the function simplify() with ...
• 70.4k
1 vote

### How to find the standard deviation in GPS measurement of latitude and longitude?

1- calculate standard deviation of latitude (sdLat) 2- calculate standard deviation of longitude (sdLon) 3- calculate DRMS = Square Root (sdLat^2 + sdLon^2) DRMS is radius measure for the error from ...
• 11
1 vote

### Surveys showing GPS accuracy in different models of smartphones?

NTDP GPS Receiver Horizontal Accuracy Reports tests lots of devices under different forest canpoies, at https://www.fs.usda.gov/database/gps/mtdcrept/accuracy/index.htm January 2023 data is there (at ...
• 121
1 vote

### How does a GPS device determine bearing?

Yes, I know this is an old topic, and I'm not answering the question as it was asked, but I hope the answer is useful to someone. Agricultural and construction equipment often has two independent GNSS ...
• 704
1 vote

### What is the lowest and highest possible pseudo-range?

GPS PR measurements are between 60 mili-seconds to 92 mili-seconds. Multiply by the speed of light to get the distance limits in meters. Please note that this limits refers to GPS satellites only, And ...
• 11

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