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Help me understand the various aspects of a GPX file


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I think I'm somewhat confused in the information within a GPX file, specifically in regards to the concept of a track. I don't understand why GPX files have multiple tracks in it. Why can't they just list all of the GPS coordinates in one long list?

 

So I need your help here because I'm trying to simplify things for myself. I have a bunch of GPX files and there are various tracks inside. How can I get the GPS coordinates to be listed from start to finish without navigating through the tracks? For example, if I turn my GPS device on at 10 AM and turn it off at 10 PM, I want every single coordinates to be listed from 10 AM to 10 PM in one continuous scrolling list. This way I can easily locate the coordinates that I'm after by locating the time that I'm after.

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You wont get every single coordinate... Take up far too much space on the GPS to record them all!

 

http://www.gpsvisualizer.com/convert_input is a good conversion site, which allows a GPX file to be converted to plain text (CSV) to allow you to print out the result.

 

The site will also show the route on a map http://www.gpsvisualizer.com/map_input?form=google from a GPX file.

Edited by Bear and Ragged
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Sgt Strider, I think the gist of your question is really "Can a track file show where you were on your track at a given time?

 

It depends a bit on which GPS you have and how the trackes were saved. Some will record a time stamp with each track point and some won't. I believe (and someone will correct me if I'm wrong) that most Garmin units do record timestamps on each track point of the ACTIVE track, but many will not include that info once you save the track to a specific named file (a way to save file space).

 

Bear and Ragged already pointed you to GPXVisualizer, and there are other packages that can show you what data is recorded in your track. It's important to geotagging photos also, so you might look for geotagging software.

 

Hope this explantion helps.

Edited by user13371
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I find it very useful to have separate track. One for each trip. I would not want them all in one big list.

On my Garmin etrex hcx you can choose some settings in the GPS about how often is records a point into the track.

In the rare case where for example i need to change batteries in the middle of a trip, i end up with 2 tracks.

I edit the .GPX file using a text editor like notepad (NOT WORD!). With a little care and understanding of the file you can re-combine tracks this way.

I expect there are other utilities to do this too.

 

The GPX format is flexable and can allow many things. It depends on the GPS and the software you use, how the GPX will be used. You might get more specific help if you posted info about the gps and software used.

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SGT, what you are describing are segments in a track file. Many GPSrs create a new segment when you turn off/on.

An essential Track utility is the program: G7toWin

You can drag one or more track file into it and see the segments and track points in a spreadsheet format. You can easily edit, delete, add, or combine the segments or track points, and save as a new GPX file. Each line(track point) will show fields such as elevation, time (in UTC), distance between points. Right mouse click to bring up edit choices.

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I think I'm somewhat confused in the information within a GPX file, specifically in regards to the concept of a track. I don't understand why GPX files have multiple tracks in it. Why can't they just list all of the GPS coordinates in one long list?

 

So I need your help here because I'm trying to simplify things for myself. I have a bunch of GPX files and there are various tracks inside. How can I get the GPS coordinates to be listed from start to finish without navigating through the tracks? For example, if I turn my GPS device on at 10 AM and turn it off at 10 PM, I want every single coordinates to be listed from 10 AM to 10 PM in one continuous scrolling list. This way I can easily locate the coordinates that I'm after by locating the time that I'm after.

 

Look at Expert GPS by Topografix....

 

What model of GPS do you have? Older model Garmins discarded some track info if you "saved" a track (because saved tracks were limited to 500 trackpoints) but if the tracks were logged to the memory card (if so equipped),then all the data was retained in that version of the file.

Newer model Garmins do not have that limitation and all the track data is retained .

 

Tell me what model GPS and specifically what it is that you are wanting to do.

 

With Expert GPS I can tell exactly when I started a track, exactly when I was at any specific trackpoint anywhere along that track, etc........all displayed in list form....isn't that what you are wanting? ALL the info that the GPS logged, for EVERY trackpoint that it logged. That is true even if you were logging trackpoints at the max number of 1/sec.

 

Sorry Bear & Ragged, but every coordinate and elevation for every trackpoint that the GPS logged on that track is listed. It has nothing to do with taking up too much GPS capacity.

 

I can tell exactly what date, time, exact coordinates,elevation, etc I was at on any given hike dating back 10 years.

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Just FYI...

For EVERY trackpoint the GPS logs, I can tell the following info....in list format....

 

Coordinates (in what ever format you want to see them)

Date created and time (local)(down to the second the trackpoint was logged)

Heart Rate (if monitor was used while track was logged)

Dist from start

Elapsed time

Dist to next

Bearing

Grade

Speed

Time (elapsed between trackpoints)

Temperature (if sensor was present and used)

Depth (if depth sensor was present and used)

Cadence

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I think I'm somewhat confused in the information within a GPX file, specifically in regards to the concept of a track. I don't understand why GPX files have multiple tracks in it. Why can't they just list all of the GPS coordinates in one long list?

 

So I need your help here because I'm trying to simplify things for myself. I have a bunch of GPX files and there are various tracks inside. How can I get the GPS coordinates to be listed from start to finish without navigating through the tracks? For example, if I turn my GPS device on at 10 AM and turn it off at 10 PM, I want every single coordinates to be listed from 10 AM to 10 PM in one continuous scrolling list. This way I can easily locate the coordinates that I'm after by locating the time that I'm after.

 

Look at Expert GPS by Topografix....

 

What model of GPS do you have? Older model Garmins discarded some track info if you "saved" a track (because saved tracks were limited to 500 trackpoints) but if the tracks were logged to the memory card (if so equipped),then all the data was retained in that version of the file.

Newer model Garmins do not have that limitation and all the track data is retained .

 

Tell me what model GPS and specifically what it is that you are wanting to do.

 

With Expert GPS I can tell exactly when I started a track, exactly when I was at any specific trackpoint anywhere along that track, etc........all displayed in list form....isn't that what you are wanting? ALL the info that the GPS logged, for EVERY trackpoint that it logged. That is true even if you were logging trackpoints at the max number of 1/sec.

 

Sorry Bear & Ragged, but every coordinate and elevation for every trackpoint that the GPS logged on that track is listed. It has nothing to do with taking up too much GPS capacity.

 

I can tell exactly what date, time, exact coordinates,elevation, etc I was at on any given hike dating back 10 years.

 

Thank you very much for that detailed response, but I'm still confused. Most of my GPX files are generated by my Garmin 60CSX. The files were saved on to the memory card with auto record method and saved most often. I believe that most if not all the coordinates are saved since I saved it on to a memory card.

 

On my last trip I started using my new Garmin 62S. Coordinates are saved every second.

 

Now I'm still confused between the concept of track and segment. I guess I don't need a perfect understanding. I just want the coordinates to be listed from start to finish and sorted by time as mentioned in the op. Will G7toWin permit this?

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...still confused...

It may be useful to readi GPX documentation for a fuller understanding. Excerpts:

 

A track (is) an ordered list of points describing a path.

 

A Track Segment holds a list of Track Points which are logically connected in order. To represent a single GPS track where GPS reception was lost, or the GPS receiver was turned off, start a new Track Segment for each continuous span of track data.

Edited by user13371
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Grass catcher - what GPS and what settings? The recorded level of detail your describe would not be available for all devices.

 

In my earlier post I believe I said later model Garmins... I've got a 76CSx, a 78S,an Oregon 550, and a Montana 650. The 76CSx doesn't have wireless (for heart rate,etc) but the rest of'em will log all of the data.

 

Of course Heart Rate, Depth,Cadence all require external equipment which connects(talks to) your GPS wirelessly.

 

Whatever data your model of GPS is capable of recording, that data is logged for every trackpoint.

 

We still don't know the specific model GPS that the OP has, or what it is exactly that they are wanting to do with the data.

edited to add: I see in a later post...60 & 62.

 

Sgt S,..... Specifically, what are you wanting to do?, can you send a GPX file?

Edited by Grasscatcher
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"Thank you very much for that detailed response, but I'm still confused. Most of my GPX files are generated by my Garmin 60CSX. The files were saved on to the memory card with auto record method and saved most often. I believe that most if not all the coordinates are saved since I saved it on to a memory card.

 

On my last trip I started using my new Garmin 62S. Coordinates are saved every second.

 

Now I'm still confused between the concept of track and segment. I guess I don't need a perfect understanding. I just want the coordinates to be listed from start to finish and sorted by time as mentioned in the op. Will G7toWin permit this? "

 

@Sgt S,

On the 60CSx, by "logging" the tracks to the card, ALL the data is there, and the "auto record" method, and "most often" interval is the most efficient and accurate way to log tracks.

 

Now, on the 62, you can't log the tracks to the card, but that's OK because the tracks are logged to the internal memory and ALL THE DATA IS RETAINED. Even if you "save" a track on the 62, all the data is retained. Just be assured that all the data is there.

Note: You can PUT a GPX file with tracks in it onto your memory card (and the unit can "read" and display the data) but you cannot have the unit LOG the track to the card.

 

The new models (like the 62) "file system" is different than on the older 60.

 

Note that on the 62,you now have an Archive function. That's a whole nuther concept .....that apparently even a number of so called experienced users do not understand the concept.

You can set your unit to "archive" track data daily, or weekly, or wrap when full, etc.

 

For whatever archive period you have your unit set on, your unit creates a gpx file with all the tracks connected. (duh,the OMG "dreaded" straight line !!) It's doing exactly what the user has told it to do by their choice of settings.Note: the user can also prevent the straight lines by their actions at the beginning and end of logging a track......nuther topic...

 

Daily archive= one archive gpx file /day (data tied together within that day)

Weekly archive=one archive gpx file /week (data tied together within that week)

(other length archive= same o,same o)

 

I don't use G7toWin but I'll try and take a look at it's capabilities. I've go it, just never use it.

 

In EGPS , within the track file, EVERY trackpoint logged by the GPS is listed in the order it was logged, and with ALL the data that that model GPS logged that specific trip.

 

Based on how you said they were logged, in the gpx files on the card from your 60CSx, and the gpx files from your 62, all the track data is there.

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"Thank you very much for that detailed response, but I'm still confused. Most of my GPX files are generated by my Garmin 60CSX. The files were saved on to the memory card with auto record method and saved most often. I believe that most if not all the coordinates are saved since I saved it on to a memory card.

 

On my last trip I started using my new Garmin 62S. Coordinates are saved every second.

 

Now I'm still confused between the concept of track and segment. I guess I don't need a perfect understanding. I just want the coordinates to be listed from start to finish and sorted by time as mentioned in the op. Will G7toWin permit this? "

 

@Sgt S,

On the 60CSx, by "logging" the tracks to the card, ALL the data is there, and the "auto record" method, and "most often" interval is the most efficient and accurate way to log tracks.

 

Now, on the 62, you can't log the tracks to the card, but that's OK because the tracks are logged to the internal memory and ALL THE DATA IS RETAINED. Even if you "save" a track on the 62, all the data is retained. Just be assured that all the data is there.

Note: You can PUT a GPX file with tracks in it onto your memory card (and the unit can "read" and display the data) but you cannot have the unit LOG the track to the card.

 

The new models (like the 62) "file system" is different than on the older 60.

 

Note that on the 62,you now have an Archive function. That's a whole nuther concept .....that apparently even a number of so called experienced users do not understand the concept.

You can set your unit to "archive" track data daily, or weekly, or wrap when full, etc.

 

For whatever archive period you have your unit set on, your unit creates a gpx file with all the tracks connected. (duh,the OMG "dreaded" straight line !!) It's doing exactly what the user has told it to do by their choice of settings.Note: the user can also prevent the straight lines by their actions at the beginning and end of logging a track......nuther topic...

 

Daily archive= one archive gpx file /day (data tied together within that day)

Weekly archive=one archive gpx file /week (data tied together within that week)

(other length archive= same o,same o)

 

I don't use G7toWin but I'll try and take a look at it's capabilities. I've go it, just never use it.

 

In EGPS , within the track file, EVERY trackpoint logged by the GPS is listed in the order it was logged, and with ALL the data that that model GPS logged that specific trip.

 

Based on how you said they were logged, in the gpx files on the card from your 60CSx, and the gpx files from your 62, all the track data is there.

 

In terms of accuracy, wouldn't auto record and most often be less accurate than setting it to record every 1 second? How often does the units record a coordinate when auto record and most often is set?

 

I think you've helped me quite a bit, but I still don't understand why the GPX files have tracks in it. Let's say I do use the EGPS app to examine my GPX files. Let's say I'm looking at a track that pertains to the period of 10 AM to noon. How can I be sure that track #1 contains all of the coordinates for that time period and that some coordinates don't end up in track number 2 assuming that there are two tracks within the GPX file.

 

I'm not sure if we're on the same page here, but why can't the GPX files just display all of the coordinates by chronological order if I used the unit from 10 AM to noon? By introducing tracks, it confuses people like me and then I'm not sure if all of the coordinates from 10 AM to noon is located over there. Now I'll have to go through all the tracks to make sure that is the case. Right?

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"In terms of accuracy, wouldn't auto record and most often be less accurate than setting it to record every 1 second?"

Not less accurate....just less efficient."

 

" How often does the units record a coordinate when auto record and most often is set? "

Here's the concept, it only takes two points to "describe" a straight line, so if you are moving straight, the unit logs fewer points. When you start to change direction, the unit logs an increased number of points to accurately "describe" that path.......up to and including as fast a logging rate of one / second. ....which is the fastest/most often that the GPS can /will log. So, really it just DOESN'T log points when it doesn't NEED to. It's exactly the same degree of accuracy, but uses fewer trackpoints. It's not nearly as important now as it used to be when GPS track lengths were limited by the number of trackpoints allowed.

 

Now, I'M totally confused!

" I still don't understand why the GPX files have tracks in it."

A gpx file from a GPS unit is a text file log of WHATEVER data the unit was doing at the time. Position,elevation,speed,etc....everything! It (a gpx file) is just a "note to memory" of any and all the actions of that GPS unit for that specific point in time.

 

Note that ALL the data is logged exactly at the point in time when it happens, and that TIME IS LOGGED ALSO......with that specific data.

 

All track #1 data (every trackpoint with all its data) is logged while it is being traveled, then when another path is traveled that is also logged, but that(track 2) happens at a different point in time which is also logged.

Example: You sat at a table and ate breakfast yesterday and wrote down where you were, what foods you ate and what time it was. Today you may have eaten the same type of food for breakfast, sat at the same table , etc.......and again you wrote all the information down, and you wrote it on the same notepad as yesterday.

 

Those are two separate instances, you can't mix and mingle them because they happened at different times. The two "Notes" you wrote describing them are (track 1 & Track 2), and the note pad you wrote the two separate notes on is (the GPX file)

 

Your last paragraph REALLY REALLY confuses me......because what you describe as what you want, is EXACTLY WHAT YOUR GPS DOES DO !

Tracks are NOT some weird / different type of object....it's just data. Trackpoint after tracpoint after trackpoint.

If you want to save your location as a separate waypoint, what you actually are doing is just creating a separately identified package for that specific location on the "breadcrumb trail" (track) that your GPS is continuously making.

If you don't want tracks created, just turn track logging OFF. Then you might as well just carry around a rock.

If you turn your GPS on at 10AM and off at 10 PM, the track that is created is made up of (thousands) of trackpoints (each with all it's own specific data) listed in chronological order!!!!!

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"In terms of accuracy, wouldn't auto record and most often be less accurate than setting it to record every 1 second?"

Not less accurate....just less efficient."

 

" How often does the units record a coordinate when auto record and most often is set? "

Here's the concept, it only takes two points to "describe" a straight line, so if you are moving straight, the unit logs fewer points. When you start to change direction, the unit logs an increased number of points to accurately "describe" that path.......up to and including as fast a logging rate of one / second. ....which is the fastest/most often that the GPS can /will log. So, really it just DOESN'T log points when it doesn't NEED to. It's exactly the same degree of accuracy, but uses fewer trackpoints. It's not nearly as important now as it used to be when GPS track lengths were limited by the number of trackpoints allowed.

 

Now, I'M totally confused!

" I still don't understand why the GPX files have tracks in it."

A gpx file from a GPS unit is a text file log of WHATEVER data the unit was doing at the time. Position,elevation,speed,etc....everything! It (a gpx file) is just a "note to memory" of any and all the actions of that GPS unit for that specific point in time.

 

Note that ALL the data is logged exactly at the point in time when it happens, and that TIME IS LOGGED ALSO......with that specific data.

 

All track #1 data (every trackpoint with all its data) is logged while it is being traveled, then when another path is traveled that is also logged, but that(track 2) happens at a different point in time which is also logged.

Example: You sat at a table and ate breakfast yesterday and wrote down where you were, what foods you ate and what time it was. Today you may have eaten the same type of food for breakfast, sat at the same table , etc.......and again you wrote all the information down, and you wrote it on the same notepad as yesterday.

 

Those are two separate instances, you can't mix and mingle them because they happened at different times. The two "Notes" you wrote describing them are (track 1 & Track 2), and the note pad you wrote the two separate notes on is (the GPX file)

 

Your last paragraph REALLY REALLY confuses me......because what you describe as what you want, is EXACTLY WHAT YOUR GPS DOES DO !

Tracks are NOT some weird / different type of object....it's just data. Trackpoint after tracpoint after trackpoint.

If you want to save your location as a separate waypoint, what you actually are doing is just creating a separately identified package for that specific location on the "breadcrumb trail" (track) that your GPS is continuously making.

If you don't want tracks created, just turn track logging OFF. Then you might as well just carry around a rock.

If you turn your GPS on at 10AM and off at 10 PM, the track that is created is made up of (thousands) of trackpoints (each with all it's own specific data) listed in chronological order!!!!!

 

Thanks for the explanation. I did said I was going to drive you crazy, but thanks for trying to help me improve my understanding of it.

 

For the purpose of geotagging images, wouldn't recording every second be more accurate? I fail to understand how the other options are more efficient since not all coordinates are recorded. As a result, when it comes time to geotag the images, I'll have to use a time offset to tag the images and depending on how big the offset is, then that's where the accuracy will vary. Am I correct with that assessment?

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Are you talking about geotagging pictures taken with the GPS (62SC??) or pics taken with a separate camera?

Pics taken with the GPS are tagged with the GPS actual time they are taken (accurate to the second) so that makes your question a mute point.

If you're talking about pics taken with another camera, then, if there needs to be a time offset used, then use it........but then you're talking about WAAAAAAAAYY more time difference than would occur due to difference in type of track logging interval....and what source would you use as the "correct" time?????

 

If it's THAT important to you to geotag pics to an absolutely precise time, then me thinks you would be "gagging on an ant and swallowing an elephant". Good grief, it's just meant to be a visual representation of where on the track a pic was taken......and by most methods, you can't even tell which way the camera was being pointed/ direction the pic was taken. (but you CAN tell that using EGPS if the pic was taken with the GPS)

Edited by Grasscatcher
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