Tagged Questions

GPS is a space-based satellite navigation system that provides location and time information.

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16
votes
2answers
12k views

What is the difference between triangulation and trilateration?

Looking around I noticed that many people exchange the terms (tringlulation and trilateration) for the same sense. What's, actually, the correct sense of Triangulation and what are the differences ...
12
votes
5answers
6k views

How to get an elevation profile for a gps track?

I'd like to get a reasonably accurate elevation profile for a track recorded with a GPS (which often has very unreliable altitude data and occasionally none at all, depending on the model.) Does ...
1
vote
3answers
100 views

Looking for a website to produce a file using UTM or LL or LL to UTM or general

Is there a website that allow me to upload my GPS file from UTM to lat and long to produce a new output file ? I am looking for one to run a batch a list of UTM or LL to converstion them in either ...
3
votes
1answer
1k views

How to calculate accuracy of latitude/longitude

I'm updating a Windows Mobile application to capture location information using the built-in GPS hardware. The Microsoft API provides a method GPSGetPosition that returns the following struct ...
6
votes
1answer
1k views

How to filter wrong GPS readings?

I have absolutely no experience with GIS, it just so happens that one of the hobby projects I am doing at the local hackerspace includes tracking a model boat with a GPS... I hope this is the right ...
8
votes
11answers
2k views

Device for Logging GPS and Accelerometer Data?

I am looking for a device that can track my location (lat,long) and speed all day long. Perhaps, I need GPS and accelerometer data bundled together. What I want to do is to log my daily activities. I ...
4
votes
1answer
4k views

How to calculate Bearing between two GPS points

The following returns 150 degrees using C# converted from JavaScript Bearing formulas, but Google earth returns 210 degrees for the same values. The broken code is GetBearing() but I've also included ...
2
votes
3answers
421 views

GPS and GIS for real time monitoring of an object

How is it possible to store coordinate of object in server in real time using feasible hardware ( can be used by student) GPS into database and retrived in real time?? What are the names of ...
3
votes
2answers
302 views

GPS capable rangefinders or cameras that can capture lat / long data from a distance?

Anyone have experience using this technology? i.e. field verifications of structures where you need to capture the lat / long of a house that is 1000 feet from the road with limited access.
3
votes
2answers
737 views

Alternative to Terrasync for Trimble Windows Mobile unit

I have a number of Trimble Nomad 900 series devices and am currently using TerraSync. TerraSync does the job, but are there any other alternatives out there that would be even simpler to use? ...
1
vote
0answers
278 views

Draw a skyplot with calculated ECEF values (in meters)

I have ECEF values that I calculated from ephemeris subframes 2/3. Using this information, I'd like to place these values on a skyplot based on my current location. I'm using a C# picture box for my ...
8
votes
3answers
3k views

Example of a Dynamic Map Service that frequently changes?

A requirement of our web application is to automatically refresh a particular dynamic map service on a timer. Requirement relates to a client who has a dynamic MS that consistently gets updates ...
5
votes
4answers
678 views

Looking for software to interface GPS data with PC

I have GPS Unit from Garmin (GPS 18xPC). I'm looking for software I can install on my PC that will allow me to interface with the data I collect on my GPS unit. Any help will be great
3
votes
1answer
318 views

How to export offsets from Trimble Rangefinder?

I already asked this question at http://www.rpls.com/forums/viewtopic/8/1276880, but didn't get any answer so far. Maybe here someone can help... I have a question about the use of Trimble Products. ...
16
votes
6answers
2k views

Sources of realtime spatial data

I'm trying to set up a demo that serves up live spatial data, but am having trouble finding any suitable example data sources. Ideally I'm looking for something that updates every few seconds; either ...
31
votes
8answers
21k views

Why does GPS positioning require four satellites?

I have a question on the GPS positioning algorithm. In all books I've read for 3D positioning we need four satellites, and I don't understand why. We need to calculate three variables: x, y, z. We ...
10
votes
2answers
488 views

What Type of GIS Powers Automobile Navigation Systems

My sister-in-law was inquiring about where she can buy updated DVD's to load into her car's system. Obviously I know the dealer/OEM would love to rip her off for such data, and I knew of no ...
17
votes
12answers
3k views

Location-based game using GPS

I am not sure if this forum is proper place for that kind of question but i hope to get some advice... I looking for some scenario (examples, ideas) for urban game (location-based game) with usage of ...
3
votes
1answer
304 views

What is the DNSC08 Mean sea surface model ellipsoid based on?

Does anyone know what Danish Space centre DNSC08 mean sea surface model uses as the reference ellipsoid? there is no meta data on the web site: ...
0
votes
1answer
1k views

how to convert the easting and northing to a point and saved in a feature class in ArcMap?

I write a program to decode the message from the GPS device to get the easting and northing , but I don't know how to convert the easting and northing to a point and saved in a feature class in ...
2
votes
2answers
842 views

GPS - Garmin 60CSX connectivity issue

I have a Garmin 60csx, about 2 years old and I have attempted to connect it to my laptop/ArcView (GPS toolbar) using the Detect GPS Port to no avail. There is no port number being displayed and that ...
2
votes
0answers
408 views

How to read a .GPB file in C#?

I have a .GPB file, I need to extract the common GPS data from it but I don't find a clear structure that specify the contents of that file. as a sample record from file 00000260 02 11 A9 61 E7 96 ...
2
votes
1answer
130 views

Finding intermediate points and speed over a segment

I have a dataset which is in the form of ( Time , Car ID, Speed at that moment, Lat,Long) and I need to do some machine learning on the data to answer the following questions : Best route from ...
1
vote
2answers
1k views

How do I download tracks from the GARMIN GPSMAP 78 usin DNRGarmin?

I have been able to download waypoints to DNRGarmin by accessing the GPX file. However, I have only been able to view waypoints. How can I download tracks?
2
votes
1answer
1k views

How to read multiple .gpx files in R [closed]

Suppose I have a number of .gpx files (these contain GPX waypoint data from a Garmin eTrex). I want to load them into R with different names and manipulate them. I can read one file thus: ...
9
votes
4answers
597 views

Does GPS signal quality depend on the chip manufacturer? Does it depend on weather?

(Sorry if GIS is not the right place to post this question to). Recently me and my school friends had a GPS software application project to pursue at the university. A device very similar to this ...
4
votes
1answer
289 views

RINEX specs and OS library

Is there any OS library to read/write/process RINEX data? I've been wanting to start a OS library to read and write RINEX, which is something I need for a project, but not actually post-process them. ...
4
votes
2answers
1k views

Point interpolation in route

I have a set of GPS coords with X,Y and Course. I need to interpolate additional points based on the course of each point. It would be a simple line intersection based on lines drawn using the 2 ...
3
votes
6answers
2k views

Garmin GPS 78 Interface

Does anyone know how to interface a Garmin GPS 78 Marine GPS with their computer to manage waypoints (upload, download, save, etc.) Previously I was using the MN DNR Garmin tool, but it no longer ...
4
votes
2answers
2k views

Trimble GeoXH, XM, XT - Data logging without Terrasync or GPSCorrect?

Is it possible to capture data for post processing on a Trimble GeoXH, XT, or XM without using Terrasync or GPScorrect? Specifically I would like to create a RINEX file. A Trimble 4000 series receiver ...
3
votes
1answer
1k views

File IMG from OSM

Is it possible to convert or open an IMG file from OSM? I don't find a solution for the visualization and conversion. Thanks
6
votes
2answers
1k views

Trimble GeoXH vs GeoXT and GPS Correct

I am about to purchase a new GPS unit. I currently have a GeoXT and have used the combo of GPS Correct/ArcPad with GPS Analyst/ArcMap to correct the collected data to submeter (or close to it). ...
1
vote
1answer
220 views

delorme gps and delorme X map alternatives

We have a group doing field work and are having issues using delorme gps and delorme X Map and Delorme X Map. Wondering if there is a way to connect the delorme GPS pn 40 to ArcReader / ArcExplorer in ...
13
votes
3answers
5k views

Post Processing GPS Data with open source software

I am using Magellan Professional Mapper CX working on ArcPad 7.1 platform. It has sub-meter accuracy after post processing. Without post processing the data collected in the field is off by 10 to 15 ...
2
votes
2answers
1k views

Locations of Geodetic Survey Benchmarks

Does anyone know where I can find a list of geodetic benchmark locations for Ontario? (If a list even exists that is...) Thanks
3
votes
1answer
501 views

Can an htm file be imported into Trimble's Data Dictionary Editor?

We've received several data dictionary files from other entities and they all are in *.htm format. We were hoping to not reinvent the wheel, as these are massive data dictionaries, so does anyone know ...
7
votes
3answers
2k views

Do's and Don'ts for GPS Localization

We have recently purchased some new GPS survey gear (ProMark 500) and we have set up a localization around the town using some of the known survey marks. While I'm pretty confident that I have got it ...
16
votes
3answers
529 views

Lightsquared GPS controversy: Where is the analysis?

GPS World reports that Lightsquared's network of 40,000 transmitters will interfere with GPS signals. Initial technical analyses have shown that the distant, low-powered GPS signals would ...
22
votes
6answers
808 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, ...
5
votes
1answer
351 views

PLT track in PostGIS

What are the best practices for importing and aggregating tracks (in my case in 'plt' format) in a PostGIS table, grouped by user. Are there any tools/db models/tutorials available?
8
votes
3answers
3k views

Calculate maximum speed from GPS data

I have raw GPS locations for a track, and need to get maximum speed. Simple methods (calculate speed between 2 points, take max) will give meaningless large numbers due to GPS inaccuracy, the point is ...
26
votes
5answers
2k views

Does an earthquake affect GPS?

There are news reports saying that the Sendai earthquake a couple days ago has shifted the earth on its axis and moved the island 8 feet. Last year, there were similar reports with the earthquake in ...
5
votes
3answers
3k views

Free MobileGIS like ArcPAD

I'm looking for open-source program like ArcPAD. I have read all questions and answers, but i find nothing. I need the program for PDA (Dell axim x51v + GPS modul) and I want mapping points (trees or ...
14
votes
8answers
2k views

Mobile Data collection options

What COTS software is available to do mobile data collection, with GPS positioning. Map display not required. I'm looking across the board (platform wise). I'm already aware of... RhinoSpect ...
5
votes
2answers
4k views

postprocessing GPS coordinates with RINEX data to improve precision?

Im doing some mapping for OSM in my region and I am curious if the precision of tracks from a GPS Receiver can be improved if they are post processed with RINEX data. The tracking is done with a ...
9
votes
10answers
2k views

Need a Benchmark GPS Trajectory data-set? Anyone?

I'm looking for a benchmark GPS data set, available for research purposes for free. I've found GeoLife GPS Trajectories dataset from Microsoft Research but I find it a little incomplete. What I need ...
12
votes
4answers
4k views

Clustering Trajectories (GPS data of (x,y) points) and Mining the data

I've got 2 questions on analyzing a GPS dataset. 1) Extracting trajectories I have a huge database of recorded GPS coordinates of the form (latitude, longitude, date-time). According to date-time ...
6
votes
4answers
1k views

How can I get my GPS track data into a graphics program?

I'm using a Garmin Edge 705 bike GPS/computer unit, which produces .gpx files. I can use the standard software it comes with to plot on Google Maps etc, but I'd like to be able to output just a vector ...
26
votes
7answers
2k views

Why don't they use cell towers like GPS satellites?

If my understanding is correct, a GPS satellite produces a pretty simple signal which is basically composed of its location and its time. Given 4 of these signals, then one can uniquely solve for the ...
4
votes
3answers
284 views

Differentiating a building from a road on a map?

This question was originally asked here by Steven and I felt the question was better asked here. Steven would also like to know the sources Google buys it maps from. I remember seeing a post about it ...