Author Topic: Etrex - Maximum length of uploaded tracklog?  (Read 10078 times)

Dave

Etrex - Maximum length of uploaded tracklog?
« on: 07 June, 2008, 05:07:34 pm »
While I was out today, I noticed (too late) that the 110km tracklog (plotted using Tracklogs) loaded into my etrex (Vista HCx) had been truncated to just less than 100km.

Does anyone know if this is a hidden 'feature' of the etrex/vista? Neither the vista manual not Tracklogs help mention it.

The full 110km track was recorded safely as I actually rode it (save for the 'I though they'd fixed that' unit switching itself off when it got a bit too bumpy 'bug')

Re: Etrex - Maximum length of uploaded tracklog?
« Reply #1 on: 07 June, 2008, 05:13:52 pm »
Theres a limit to the number of trackpoints, or waypoints, you can have in a track. I cant remember how many, I'll google it in a minute, but I know when I first got mine I came up against this. The easy way round it is to split long routes into more than one track.

Maladict

Re: Etrex - Maximum length of uploaded tracklog?
« Reply #2 on: 07 June, 2008, 05:21:14 pm »
On the eTrex Vista HCx the limit is 500 points (it's stupidly low).

You can filter the track before uploading to avoid this problem; Tracklogs has this facility as does MapSource.

Go to edit->properties, and then click on the point filter tab.  Then drag the slider down til the track is no more than 500 points.

It'll show you the maximum deviation this causes.  It's quite possible to fit a much longer ride into 500 points so you shouldn't have a problem with a 110km ride.  I just tried reducing a 300 from 776 to 500 pts and it introduced a maximum deviation of 50m, which is generally fine.

If I create a long track I generally split it into subsections; this can't be done in Tracklogs (not V2 anyway) but tools like GPS Utility can do it, or you can convert the track to GPX, load into an editor and split it there.

Dave

Re: Etrex - Maximum length of uploaded tracklog?
« Reply #3 on: 07 June, 2008, 05:40:42 pm »
On the eTrex Vista HCx the limit is 500 points (it's stupidly low).

You can filter the track before uploading to avoid this problem; Tracklogs has this facility as does MapSource.

Go to edit->properties, and then click on the point filter tab.  Then drag the slider down til the track is no more than 500 points.

It'll show you the maximum deviation this causes.  It's quite possible to fit a much longer ride into 500 points so you shouldn't have a problem with a 110km ride.  I just tried reducing a 300 from 776 to 500 pts and it introduced a maximum deviation of 50m, which is generally fine.

If I create a long track I generally split it into subsections; this can't be done in Tracklogs (not V2 anyway) but tools like GPS Utility can do it, or you can convert the track to GPX, load into an editor and split it there.


Ah. Thank you for this, it wasn't that the tracklog was >100km, it was because it had 593 points. What a stupidly low limit >:(. Have Garmin said why it's that low, or whether they'll be fixing it?

I've only ever plotted 50/60km max MTB tracks up to know, so it'd never come up as a problem...

Now I know I can work round it - plot less points or split the route into chunks (I'm only likely to be plotting tracks this long for audaxes, so I can split them into start to control 1, control 1 to control 2 and so on).

Re: Etrex - Maximum length of uploaded tracklog?
« Reply #4 on: 07 June, 2008, 10:22:56 pm »
eTrex will do 10,000 points for tracklogs; it's routes where the 500 limit applies.

Routes carry more data than trackpoints, hence the difference in limits (plus the marketing department clearly got a look-in).

To work around the 'switch off on a bump' issue, use an external battery.

Maladict

Re: Etrex - Maximum length of uploaded tracklog?
« Reply #5 on: 07 June, 2008, 10:54:48 pm »
eTrex will do 10,000 points for tracklogs; it's routes where the 500 limit applies.

Routes carry more data than trackpoints, hence the difference in limits (plus the marketing department clearly got a look-in).

To work around the 'switch off on a bump' issue, use an external battery.


Routes are limited to 50 waypoints.  I think you are confusing the active log with saved tracks.  The active log is something like 10,000 points.  Saved tracks are 500 points.  Longer than this are truncated when you upload them to the unit.

Re: Etrex - Maximum length of uploaded tracklog?
« Reply #6 on: 08 June, 2008, 09:27:34 am »
eTrex will do 10,000 points for tracklogs; it's routes where the 500 limit applies.

Routes carry more data than trackpoints, hence the difference in limits (plus the marketing department clearly got a look-in).

To work around the 'switch off on a bump' issue, use an external battery.


Routes are limited to 50 waypoints.  I think you are confusing the active log with saved tracks.  The active log is something like 10,000 points.  Saved tracks are 500 points.  Longer than this are truncated when you upload them to the unit.


Perhaps a difference in models - both my etrex H and etrex Summit definitely accept more than 50 waypoints per route (and definitely not confusing it with the tracklog).

Edit: Could also be terminology - I'm not familiar with Tracklogs (the product) but what Garmin call a 'track' is a recorded track (where you've been) and the path to follow a 'route'. Sounds like 'Tracklogs' actually creates what Garmin would call a 'route'?

Also found a reference on the 'net that since April 2005 eTrex models have been fitted with a larger memory chip, which may have affected the limits. For example, this GPX / MMO route contains over 50 waypoints for anyone who wants to experiment.



Dave

Re: Etrex - Maximum length of uploaded tracklog?
« Reply #7 on: 08 June, 2008, 09:39:58 am »
eTrex will do 10,000 points for tracklogs; it's routes where the 500 limit applies.
Routes carry more data than trackpoints, hence the difference in limits (plus the marketing department clearly got a look-in).

Routes are limited to 50 waypoints.  I think you are confusing the active log with saved tracks.  The active log is something like 10,000 points.  Saved tracks are 500 points.  Longer than this are truncated when you upload them to the unit.


Perhaps a difference in models - both my etrex H and etrex Summit definitely accept more than 50 waypoints per route (and definitely not confusing it with the tracklog).

It must be a model-related thing. The track saved by the Vista can definitely have thousands of track points. But, as I found, a track you plot and upload is limited to 500, which is just daft :(

I've never used routes before (and the Vista manual says that it can store 50, with up to 250 points each). I think I'll have to play around with them some more now I'm doing more road riding with the Vista...

Chris S

Re: Etrex - Maximum length of uploaded tracklog?
« Reply #8 on: 08 June, 2008, 09:48:43 am »
My Vista Cx definitely truncates uploaded tracks to 500 points.

I use mine in Off-Road mode when following a route, but also upload a track of the route (converted from the "follow road" route from Mapsource, using WinGDB) so that the "follow road" route is painted on the map as I ride.

In order to do this, I have to break the track into 500 point sections (using Mapsource and a lot of Cut/Paste!).

Maladict

Re: Etrex - Maximum length of uploaded tracklog?
« Reply #9 on: 08 June, 2008, 01:50:23 pm »
eTrex will do 10,000 points for tracklogs; it's routes where the 500 limit applies.

Routes carry more data than trackpoints, hence the difference in limits (plus the marketing department clearly got a look-in).

To work around the 'switch off on a bump' issue, use an external battery.


Routes are limited to 50 waypoints.  I think you are confusing the active log with saved tracks.  The active log is something like 10,000 points.  Saved tracks are 500 points.  Longer than this are truncated when you upload them to the unit.


Perhaps a difference in models - both my etrex H and etrex Summit definitely accept more than 50 waypoints per route (and definitely not confusing it with the tracklog).

Edit: Could also be terminology - I'm not familiar with Tracklogs (the product) but what Garmin call a 'track' is a recorded track (where you've been) and the path to follow a 'route'. Sounds like 'Tracklogs' actually creates what Garmin would call a 'route'?

Also found a reference on the 'net that since April 2005 eTrex models have been fitted with a larger memory chip, which may have affected the limits. For example, this GPX / MMO route contains over 50 waypoints for anyone who wants to experiment.




The GPX file you linked to doesn't contain /any/ waypoints.  :)  It does contain route points which are different and carry less information - and you can have more of them.  I've no idea what the limit for that on mine is, I've never hit it.

Tracklogs definitely creates tracks.  And the HCx certainly does truncate them to 500 points when they are uploaded.

There certainly are differences between models.  The old Vista (non colour) that I have can store 750 points per saved track.

Re: Etrex - Maximum length of uploaded tracklog?
« Reply #10 on: 08 June, 2008, 02:36:52 pm »
The GPX file you linked to doesn't contain /any/ waypoints.  :)  It does contain route points which are different and carry less information - and you can have more of them.  I've no idea what the limit for that on mine is, I've never hit it.

The route point limit seems to be about 122 per route (on a bog standard yellow Garmin eTrex anyway).

This is enough for most 200s, or a rural 300 (the Elenith was under 70 route points). I tend to split routes into chunks anyway otherwise the GPS gets confused if the first part of the ride out is the same as the way back in. This also allows you to see the GPSes guess at the ETA of the end of the chunk (useful if it's a control).

The same GPS has a limit of 20 routes, although I'm not sure if you can have 20 * 122 routepoints. If I get time I'll upload a bunch of routes to the GPS today (I know how to have a fun afternoon!) to see what limits I can find.

As people have pointed out. It's all about the terminology. AIUI there are 4 separate types of points:-

trackpoints
waypoints
routepoints
viapoints

Each has different uses and much different limits.
"Yes please" said Squirrel "biscuits are our favourite things."

Re: Etrex - Maximum length of uploaded tracklog?
« Reply #11 on: 08 June, 2008, 07:02:47 pm »
The same GPS has a limit of 20 routes, although I'm not sure if you can have 20 * 122 routepoints. If I get time I'll upload a bunch of routes to the GPS today (I know how to have a fun afternoon!) to see what limits I can find.

1014 routepoints seems to be the limit on my basic yellow Garmin eTrex.
"Yes please" said Squirrel "biscuits are our favourite things."

frankly frankie

  • I kid you not
    • Fuchsiaphile
Re: Etrex - Maximum length of uploaded tracklog?
« Reply #12 on: 09 June, 2008, 02:11:12 pm »
trackpoints
waypoints
routepoints
viapoints
Each has different uses and much different limits.

I think there is a lot of slack terminology - on Garmin's part as much as anyone else's.

Given that a 'waypoint' is just a pair of co-ordinates in a wrapper, all the others are just variants and you can add to the list, map points, POIs and geocaches.  They are all information-rich to a greater or lesser degree which might help explain why there are diffierent limits on different types. 
The oft-quoted and misquoted 'waypoint limit' refers to what are best described as 'user waypoints' which have the potential to be very information-rich indeed.

The trackpoint limit of 500 on a saved or uploaded track is indeed ridiculously low, given that trackpoints are very simple points.  On a card-carrying model you can daily-dump the tracks to card which is not subject to the 500 limit.  The active track limit of 10,000 is not the default out of the box - it comes set to something like 3000 but you can raise that in the menus.
when you're dead you're done, so let the good times roll

Re: Etrex - Maximum length of uploaded tracklog?
« Reply #13 on: 09 June, 2008, 02:14:03 pm »
...Could also be terminology - I'm not familiar with Tracklogs (the product) but what Garmin call a 'track' is a recorded track (where you've been) and the path to follow a 'route'. Sounds like 'Tracklogs' actually creates what Garmin would call a 'route'?

Ah! So that's why my Legend Cx gets confused when I try to save Tracklogs er, stuff, to it as a track and then tell it to navigate the track (the answer is to Save as Route to the GPS).

But the yellow Etrex worked perfectly happily that way...

I don't use mapping on the GPS, preferring the compass arrow. If only they made a simple, non-mapping GPS with the battery life, trackpoint capacity and satellite-gripping tenacity of the HCx models...
Profit or planet?

Dave

Re: Etrex - Maximum length of uploaded tracklog?
« Reply #14 on: 09 June, 2008, 02:27:11 pm »
Ah! So that's why my Legend Cx gets confused when I try to save Tracklogs er, stuff, to it as a track and then tell it to navigate the track (the answer is to Save as Route to the GPS).

That's the advantage (YMMV) of uploading track(log)s. You specify the exact route you want to follow and the GPS overlays the track(log) over the basemap. But it won't navigate the track for you.

frankly frankie

  • I kid you not
    • Fuchsiaphile
Re: Etrex - Maximum length of uploaded tracklog?
« Reply #15 on: 09 June, 2008, 02:32:29 pm »
Ah! So that's why my Legend Cx gets confused when I try to save Tracklogs er, stuff, to it as a track and then tell it to navigate the track (the answer is to Save as Route to the GPS).

Or you can invoke 'Trackback' on a Track which gives an overall experience which is not far short of navigating a programmed Route.  You get 'distance to next' and if there's a kink of more than about 30degrees you get beep and a turn instruction.
when you're dead you're done, so let the good times roll

Maladict

Re: Etrex - Maximum length of uploaded tracklog?
« Reply #16 on: 09 June, 2008, 02:34:59 pm »
Fairly easy to go wrong at instructions of the form R(SO) on LH bend which is why I stopped doing it that way.

Re: Etrex - Maximum length of uploaded tracklog?
« Reply #17 on: 09 June, 2008, 10:20:03 pm »
I suspect one of the reasons for making the distinction between the various point types is limited computing power; while it's easy to *record* lat/lon/ele/time data, if given the current position and time (by GPS) then matching it against a pre-programmed route is a surprisingly complex problem (esp. if you consider a route that crosses itself, e.g. figure of 8 or worse - how is the GPS unit to handle the crossover? Obviously, the shortest route to the final destination is to ignore the second half of the '8').

The most useful feature of a GPS unit *by far* is the ability to report the current grid reference - to be honest, that and an OS map (paper or electronic) are all I need.

Maladict

Re: Etrex - Maximum length of uploaded tracklog?
« Reply #18 on: 09 June, 2008, 10:34:08 pm »
Route crossing/intersection is easy if you have a context - you know you just did point N, so you are heading for point N+1.  It's pretty easy to see how the eTrex HCx works out which point is next as well - it goes by taking the line bisecting the angle between points N-1, N, N+1; if you are one side of that line then you are heading for point N, if you are the other then point N+1.  If you head back across that line it switches back from N+1 to N.

It generally only gets confused when you start next to a crossing point.  There is no context for it to use to determine where next and it seems to select the later option (i.e. ignoring the first half of the route, not the second).

This is currently of great interest to me as I have to implement it for a hobby project I am working on.  :)

Re: Etrex - Maximum length of uploaded tracklog?
« Reply #19 on: 09 June, 2008, 10:46:20 pm »
The GPS certainly did odd things on way out of the Elenith as I had the whole route in one (and the outbound route is the same as the inbound all the way to Tenbury Wells).

It got confused again on the way out where the route uses the same stretch of the A44.

It definitely prefers to think you're further down the route if there's a choice of two points.
"Yes please" said Squirrel "biscuits are our favourite things."

frankly frankie

  • I kid you not
    • Fuchsiaphile
Re: Etrex - Maximum length of uploaded tracklog?
« Reply #20 on: 09 June, 2008, 10:47:02 pm »
The most useful feature of a GPS unit *by far* is the ability to report the current grid reference - to be honest, that and an OS map (paper or electronic) are all I need.

I think the 'killer feature' of GPS is the 'distance to next' waypoint.  Given this, you know how long you can spend with the fairies before paying attention again.  
This is what you miss out on if you just navigate by following a track - all that in-built functionality just tossed aside ...
when you're dead you're done, so let the good times roll

Re: Etrex - Maximum length of uploaded tracklog?
« Reply #21 on: 09 June, 2008, 10:50:52 pm »
+1 to that.

It's one of the biggest reasons I prefer GPS navigation by sparse routes than an ever moving arrow of a tracklog.
"Yes please" said Squirrel "biscuits are our favourite things."

Chris S

Re: Etrex - Maximum length of uploaded tracklog?
« Reply #22 on: 09 June, 2008, 10:59:51 pm »
A combination works best for me. A route point for each instruction to provide a beep/light up prompt, plus a track to provide the painted route on the map.