User should be able to enable/disable automatic route recalculation

[aerostitch]

Issue migrated from trac ticket # 1000

component: core | priority: minor | keywords: routing, refresh

2012-01-16 14:31:33: ciprian.alexan@yahoo.com created the issue

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Currently, route is automatically recalculated when deviating from the calculated path. I think this needs to be configurable. User should be able to enable or disable automatic route recalculation. Allow me to explain why I think this is needed.

I used to use this feature a lot on iGo. This is very useful.

Let's say that we can disable automatic route recalculation, and we are driving as advised by the satnav software. Let's also say that we are driving on a very long route, like Madrid to Moscow. Even though for some reason Navit is unable to calculate such a long route, let's assume that it can. Offtopic: I think Navit being unable to calculate long routes is currently it's biggest problem.

At some point, we are warned about the low fuel. There is a gas station 200 meters away from the highway, at the next exit. When leaving the highway, Navit should only warn about deviating from the route. The route should remained drawn on the screen, along with the actual vehicle position that is updated/redrawn as configured. After fuelling, we can turn back and merge with the route calculated initially and continue driving towards our destination.

With the current behaviour, when leaving the highway for the gas station in the scenario above, Navit would recalculate the route. In case of a long route, this action would need a lot of computing resources.

Disabling automatic route recalculation is also suitable in other situations. The map may be somehow wrong, and Navit may see the vehicle out of the route. In this case, no recalculation is wanted. If Navit warns about leaving the route, the user may realize that this is only a map/gps error and he's driving on the correct path.

The same thing may happens if GPS module will return a wrong position. User will see that it drives near the designated route, on a street parallel with the highway. The user will realize that he is driving on the correct path, as he is driving on the highway, and not on the street parallel to it. Eventually, Navit will report the vehicle on correct path.

There is a down-side of this feature. Route recalculation is needed. This is when missing a highway exit, or a road is blocked. This is why we need a new Navit feature. Navit user should be able to manually trigger route recalculation. This should be some command that may be assigned to a button on the OSD.

Ciprian Alexan.

[aerostitch]

2012-01-21 11:41:46: @sleske commented

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I believe that users usually do want automatic recalculation. If you deviate from the calculated route for some reason, you usually want the route to be updated, because you may not be able to simply go to the route the same way you came (because of e.g. one-way streets), and because a different route may be shorter now. It's true that recalculation can be resource-intensive, but that should be fixed, instead of disabling re-calc altogether.

If the map or the GPS position are wrong, recalculation may not be ideal - but there's no way for the software to know if the user did not just take a wrong turn, so it's still better to recalculate.

[aerostitch]

2012-01-21 11:44:42: @sleske commented

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That said, if you want to disable recalculation, you can just abort navigation, then restart it later (just select the latest destination from the "Recent destinations" list.

It's true, however, that there's no way (AFAIK) to stop recalculations, but still keep the navigation instructions on-screen. If would probably be possible to create a GUI command to enable/disable automatic route recalculation; you could then bind that to an OSD button. Maybe someone will feel like implementing it...

[aerostitch]

2012-02-02 14:23:37: ciprian.alexan@yahoo.com commented

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Hi Sebastian,

I couldn't agree more with whet you said above. But there are some scenarios where I feel the need of disabling automatic route recalculation.

This is what actually happened to me. I was driving the highway. Next to the highway, there's a parallel local road. Due to map or GPS errors, naigation software sees the vehicle on the road. When on local road, satnav instructs to turn around as there is highway entry. Few moments later, satnav software sees the vehicle on the highway and tells to go further. The problem is that this bouncing on/off the highway was very frequent.

So it's happening something like this: now, I'm driving the highway. 10 seconds later the nice lady tells me to turn around (as she thinks I'm traveling on the road beside). 10 seconds later she tells me to go further, as she thinks I have joined the highway. Other 10 seconds later, I hear a new instuction to turn around. 10 seconds and a new instruction: go further. She starts to sound like my wife.

Because of the scenario above, I started to disable route recalculation on the satnav software I used before Navit. Disabling navigation (or deleting the route) is not an option, as route drawn on screen would be lost. I think that ability to diabling route recalculation would be a great value addition to Navit.

Bad part is that a similar feature can not ne implemented on wife.

[aerostitch]

2012-07-20 05:08:49: @mvglasow commented

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A few thoughts on this:

• If I remember that correctly, recalculating will be faster than the initial route calculation because only a short piece - from your current location to your destination - needs to be recalculated.
• The case described above is primarily caused by an inaccurate position. Improving resilience would provide some relief here. One way would be to extend "snap to roads" to give preference to the road that the vehicle was last seen on - because cars seldom jump the guard-rail. As a further refinement, we can also give a higher preference to roads that are on the route - from behavior I have seen on some commercial sat-navs, I believe they work this way.
• When off the route, displaying turn instructions is not really trivial. What might work: keep displaying the original route as a line on the map. (We can recalculate in the background and in cases like the one you describe, stop recalculation as soon as the vehicle hits the original route again.) We could then display the turn instruction for the nearest turn on the route.

[aerostitch]

2012-07-20 05:08:49: @mvglasow

[aerostitch]

2013-07-13 00:06:58: usul changed priority from major to minor

[aerostitch]

2013-07-13 00:06:58: usul

[aerostitch]

2013-07-13 00:06:58: usul commented

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Not sure if this feature will be really usefull with a general change in behaviour. Maybe a "pause routing" feature would be a good step forward?

As this issue isn't that clearly discussed, I schedule it for next major release