2 observations with fixed routes.

[FrankB]

I'm not taking that bet. I'd lose ! I'd quite happily bu you a beer though.

And I'd quite happily drink that beer with you. If you ever get to Holland let me know...

[FrankB]

I wonder if this behavior is different if the track was created by the XT rather than by Basecamp.

Just wondering how you create a track on the XT. By using the track recorder? It would surprise me if that would create a different Trip.

[Peobody]

Just wondering how you create a track on the XT. By using the track recorder?

That was my thinking. I have never done it.

[jfheath]

You can use the track recorder,

or

You can use the track menu tab icons. The one that looks like a keypad accesses the automatically recorded tracks (they are turned on by default). These can be saved with a name of your choosing.

Personally I dont think theres much point in changing the mimport flag for tracks or tracktrips. If my assumption is correct that it is this that affects the route calculation algorithm that is used, it will change it to one that heads for the next route point. Either there isn't one, or it will calculate a route to the end point.

2nd thoughts - that would be interesting to know. it wouldn't confirm my theory, but it could disprove it.

[Peobody]

If my assumption is correct that it is this that affects the route calculation algorithm that is used, it will change it to one that heads for the next route point. Either there isn't one, or it will calculate a route to the end point.

If there aren't any route points in a tracktrip then it seems to me that there are only two recalc options, calculate to the closest entry point or calculate to the end point. Based on what I have read, when you go off-route while navigating a track, a dotted line appears between your location and the closest spot in the route. To me that demonstrates that there should be a way for a calculation to be made back to the route.

Perhaps Garmin created their algorithms such that for triptracks, emphasis is on following the track instead of the point-to-point calculation that it does with trips. Even if they did, a triptrack is not appropriate when via points are needed, although, one triptrack for every via point to via point might work. That would require a tremendous amount of effort.

[jfheath]

If there aren't any route points in a tracktrip then it seems to me that there are only two recalc options, calculate to the closest entry point or calculate to the end point. Based on what I have read, when you go off-route while navigating a track, a dotted line appears between your location and the closest spot in the route. To me that demonstrates that there should be a way for a calculation to be made back to the route.

Yes. Go back to my earlier post. When you deviate, Both track and track trip find the closest point on the magenta line. Track plots a dotted straight line, track trip navigates to it. Track trip also alters the magenta line, tagging this new section onto the original at the closest point. This then becomes the new magenta line - discarding any of the original that was before the closest point. That behaviour seems to me to be the same as what being stuck in a RUT does.

Perhaps Garmin created their algorithms such that for triptracks, emphasis is on following the track instead of the point-to-point calculation that it does with trips. Even if they did, a triptrack is not appropriate when via points are needed, although, one triptrack for every via point to via point might work. That would require a tremendous amount of effort.

I think that the algorithm is something like this. (Excuse the use of quote boxes for this)

If not on magenta line

if following a track

Draw dotted straight line to closest point

else - must be a navigable

If mImport is true - eg tracktrip

Plot new magenta line to Closest Point

else - eg normal route

Plot new magenta line to next route point

Something that is an interesting behaviour that I haven't seen anyone complain about yet.

If following an elongated 'circular' tracktrip ie a long narrow oval, and you wander off route to the middle of the oval, at some point you may become closer to the other side of the oval. The tracktrip will plot a route to the closest point and it will discard the original up to that point. This is most likely to happen when setting off on a route and it will make your entire day out rather shorter than you anticipated.

[FrankB]

If mImport is true - eg tracktrip

I'm trying hard not to look like a smartass. But I would change that line to:

If mImport is true or mPreserveTrackToRoute is true eg Imported trip or tracktrip
[/quote]

[FrankB]

Come to think of it. This is how it should work. (Replace mImported by mPreserveToTrack)

if following a track
Draw dotted straight line to closest point
else - must be a navigable
If mPreserveToTrack is true - eg tracktrip
Plot new magenta line to Closest Point
else - eg normal route
Plot new magenta line to next route point

[Scottnet]

Interesting discussion. May or my not be relevant.

I had a circular trip created from a track. (From finish to start) I was following this clockwise. At around a quarter of the way round ( so 3 o'clock if you imagine the loop)I restarted the route. And choose CEP.

Instead of sending me in the expected direction of South ( towards6 o'clock) , it tried to route be west (towards 9 o'clock) to pick up the track.

I reported to Garmin. They had no explanation of why this is.

[Peobody]

Instead of sending me in the expected direction of South ( towards6 o'clock) , it tried to route be west (towards 9 o'clock) to pick up the track.

I am not a 'track' person other than having one showing on my map that corresponds with the route I am riding. So, my conjecture is that since tracks don't contain route points except start and end, somewhere around the 9 o'clock point would be the point in the track closest to where you are and the end point. From the XT 's point of view, it's job is to get you to the end point the fastest way possible (assuming
"Faster" is configured), using whatever part of the route fits that agenda.