Question about next destination starting point?

[Peobody]

Using simulation mode I tested how the XT behaves when the 3nd WP is selected as the next destination when starting a route. My goal was to determine whether the XT ignores all points between the current location and the selected entry point. Unfortunately I couldn't tell because in simulation mode the route starts at the selected entry point. Please let me know whether the XT ignores all points between current location and selected starting point.

Also, If it does, does the calculation to the selected entry point result in a recalc of the entire route?

[jfheath]

Using simulation mode I tested how the XT behaves when the 3nd WP is selected as the next destination when starting a route. My goal was to determine whether the XT ignores all points between the current location and the selected entry point.

Yes - it heads 'straight' for the selected Via Point ignoring any route points in between. It only lists the points that are Via Points in the route, so if you only have the start and the finish, and you choose the finish (because you are already at the start, it will ignore your entire route). It is one of the reasons that I quote for not having the start where your bike is parked. Have it half a mile up the road, or on the road you want to be on after leaving the built up area. Then you can select that, the satnav will take you there and continue naviagting form that point on.

Unfortunately I couldn't tell because in simulation mode the route starts at the selected entry point.

[Edit] @Peobody's observations are correct. In simulation mode when selecting next destination, the XT will simulate navigating the entire route and re-position the bike at the last known real location, and as soon as Go! is selected, reposition the bike at the starting point of the route. I have deleted my original reply as it was absolutely wrong. I'd normally leave it and flag it as wrong, but Peobody has quoted it in his response, so the context of the discussion can still be followed.[/Edit]

Also, If it does, does the calculation to the selected entry point result in a recalc of the entire route?

No. It calculates the route as it see fits - I think that it uses the current settings and avoidances - eg Faster Time, Avoid Motorways, but that may be an assumption. I don't remember ever having tested it. Just observed it.

The remainder of the original route remains as it was when it was loaded.
But beware - the XT seems to sneakily recalculate the route at other times, - I've never quite worked out when (except when deviating, when traffic alterations are accepted. It recalculates the entire route whenever Skip or Edit Route is pressed.

This was one of the first tests that I did with my XT two+ years ago. The software has 'been improved' since then, so it may have changed, but I think I would have noticed.

See this page.
app.php/ZXT-P32

Closest Entry Point - when it works - is an excellent tool for jumping into the route part way. It finds the point that is closest to where you are, and navigates to that point. It ignores any route points (via and shaping) that were before that point, and navigates the rest of the route from that point onwards, starting with whichever route point comes next - Shaping or Via.

I did some early testing on this - as it was a brand new feature to any Zumo (I think) at the time. This was version 2.30 of the software. I was disappointed, because all it did was head for the nearest Via Point. Between 2.30 and 2.90, they made a series of changes to it, which I found fascinating in the way that the programmes thought of different route points. At one point, they headed for Via Points or any shaping point that had first been created as a Waypoint - which made me wonder whether the programmers knew the difference between the different route point types. The next version corrected this and it would head for the nearest route point in the direction of the route. Then it ignored route points completely and headed for the closest point on the route. I was fascinated how they developed a solution - and dismayed that they were doing it piecemeal on a product that I reckon should have been tried and tested before it was sold ! But it was nice to watch it progress.

It gets it wrong sometimes. If U turns are disallowed and you are facing the wrong way; if the entire route is ahead of you; if your location in relation to the route makes finding the closest point, difficult. But an error is easy to spot by using the preview map. The biggest error I had was when it headed 250 mile south to some random roundabout, and then headed north again. That was when U turns were disabled, and I was sitting at my desk.

I have always had good results when I am a little way (a few miles) to one side of the route. The mathemetician in me recognises that it is relatively easy to find a straight line from a point to meets another line at right angles - which would be a good simple analogy for finding the shortest distance.

[Peobody]

Unfortunately I couldn't tell because in simulation mode the route starts at the selected entry point.

I don't think that is correct. I may be wrong - but in simulation mode, it starts wherever the bike is positioned - and you can set the bike to be in any location that you wish if GPS is turned off. Tap the screen as if placing a waypoint flag. Tap the caption giving the name assigned to that location and scroll down. Under Routes, Parking, Adventure, BirdsEye etc is 'Set Location'.

No joy here with that. When in simulation mode satnav location capability is disabled so bike location is unknown. Default is last know location.
In my test running a route in simulation mode, it always starts at the selected entry point regardless whether the location is left unchanged (last know location) or manually set before starting the route. That issue is mute though. My biggest concern was whether a recalc of the entire route would occur. I'm glad that it won't, at least with some level of certainty.

It is contradictory though that a skipping points to start at a specified entry point does not cause a recalc of the entire route but skipping a point mid-route does. The logic is obviously there to calculate a route to a specified point and then follow the route from there so... Oh crap, I feel a rant coming on... Rant suppressed.

[jfheath]

Ah - you are right, I was wrong about simulation mode. I never noticed that before. My apologies. I have deleted my wrong reply so as not to confuse other readers later. Usefully, you have quoted it, so that keeps the that part of the discussion intact.

In simulation mode, based on what I have just done, the bike goes to my current position and the selection of next destination is completely ignored. It then navigates the route intact - moving the bike again to the start of the route.

If you try it in normal mode, the preview map, and more reliably the small scale map view from the main nav screen, both show the route that is to be followed - and misses out all of the route points before the selected Next Destination with a new route to that point and the original route left intact after that point.

To get the small scale map showing the full route, tap the top bar on the navigation screen, and then the map symbol.

Test it for yoursel - but you'll need a test route starting close to where you are.

That is really odd because i tested the closest entry point behaviour in simulation mode and positioned the bike exactly where I wanted in order to check out behaviour. That is still the case.

[Peobody]

If you try it in normal mode, the preview map, and more reliably the small scale map view from the main nav screen, both show the route that is to be followed - and misses out all of the route points before the selected Next Destination with a new route to that point and the original route left intact after that point.

Confirmed! Thanks!

Also, thanks for the tip on how to access the small map. Somebody recently posted something like "every day is a school day". I second that sentiment!

[jfheath]

..... more reliably the small scale map view from the main nav screen,

I say the small scale map from the main screen is more reliable because on just a few occasions I have noticed that the preview map doesn't show the modifications that may happen to the route after Go! has been pressed. Mostly this map is identical to the preview. But just a few times, it hasn't been.

[Iris]

^^^ all of this, is precisely why I create tracks (from my routes) and sandwich them under the route while I travel. It is then very, very easy to see whether the route has mysteriously recalculated.