GPX Versions 1.1 vs 1.2 for Garmin Visually Explained
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@mzokk On the XT/XT3, I have recalculation set to prompted and almost always select NO at decision time. Like with @steve-jarrell, I prefer to manually manage my own off-route scenarios. In experimenting with XT off-route recalculation ON, I haven't encountered anything fatal other that it tries to get you back to the exact point where the off-route began to start with. Where 1.2 does become a problem is where you modify your route with adding another Via Point using either the Search function or Up Ahead. That's easily remedied by instead starting a new route through Seach/Up-Ahead and then restarting your main route with "Closest Entry Point" after reaching the Seach/Up-Ahead destination. I've experimented with this probably a dozen times under slightly different scenarios, and it consistently works.
I understand that you have a different view of things with your route planning to accommodate optional loops and other anomalies. That's cool. But off-route recalculation with 1.2 does work if you understand how it works and the specific scenarios to avoid.
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@mzokk On the XT/XT3, I have recalculation set to prompted and almost always select NO at decision time. Like with @steve-jarrell, I prefer to manually manage my own off-route scenarios. In experimenting with XT off-route recalculation ON, I haven't encountered anything fatal other that it tries to get you back to the exact point where the off-route began to start with. Where 1.2 does become a problem is where you modify your route with adding another Via Point using either the Search function or Up Ahead. That's easily remedied by instead starting a new route through Seach/Up-Ahead and then restarting your main route with "Closest Entry Point" after reaching the Seach/Up-Ahead destination. I've experimented with this probably a dozen times under slightly different scenarios, and it consistently works.
I understand that you have a different view of things with your route planning to accommodate optional loops and other anomalies. That's cool. But off-route recalculation with 1.2 does work if you understand how it works and the specific scenarios to avoid.
@John-S-Parry I've no issue with GPX 1.2 or switching off recalculation. But I can't get it to work with recalculation on, as demonstrated earlier in this thread when I ran a test. It could be user error and if it is I'd gladly hear a remedy as it would be a handier format to use in some scenarios.
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@mzokk All of my 1.2 testing has been on the XT3. With recalculation ON, it consistently tries to route me back to the point where off-route started. That's what it's designed to do. If your XT isn't behaving the same, please explain what it's doing. I tried to figure that out from your earlier post but couldn't get what was going on.
My XT has been collecting dust for the past 2-months, and it was dead when I brought it out this morning. It's charging now, and I'll do an XT 1.2 off-route test tomorrow and share what happens.
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@mzokk but I was wondering if, despite the break in the HERE mapping on MRA, the Zumo would have routed through it anyway. Can you remember if the break was also on the Zumo map? And maybe not such a stupid idea as OSM mapping is one of the detailed maps in the unit. How and why they are used, I do not know.
@john-s-parry during my testing and actually using a GPX1.2 route on the XT2 with auto-recalculation left on, sometimes it requested a U-turn or two if I carried on my diversion before changing its mind and calculating a way to get me back on the route ahead. And sometimes it would just go straight for the up-ahead re-join. It may go for the quickest option and also take into account one-way streets etc.
The only avoid option I have in the Zumo is unpaved roads. Everything else allowed. I hope the XT result is the same but I'm a little dubious.
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@mzokk but I was wondering if, despite the break in the HERE mapping on MRA, the Zumo would have routed through it anyway. Can you remember if the break was also on the Zumo map? And maybe not such a stupid idea as OSM mapping is one of the detailed maps in the unit. How and why they are used, I do not know.
@john-s-parry during my testing and actually using a GPX1.2 route on the XT2 with auto-recalculation left on, sometimes it requested a U-turn or two if I carried on my diversion before changing its mind and calculating a way to get me back on the route ahead. And sometimes it would just go straight for the up-ahead re-join. It may go for the quickest option and also take into account one-way streets etc.
The only avoid option I have in the Zumo is unpaved roads. Everything else allowed. I hope the XT result is the same but I'm a little dubious.
@mzokk but I was wondering if, despite the break in the HERE mapping on MRA, the Zumo would have routed through it anyway. Can you remember if the break was also on the Zumo map? And maybe not such a stupid idea as OSM mapping is one of the detailed maps in the unit. How and why they are used, I do not know.
No the Zumo would not have routed through the gap. I was using Basecamp. The map on the unit and the computer were identical. The only way to get the Zumo to route past that section was to put the "Direct" section in.
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Being a new guy here, I’ve been mostly quietly following this discussion. I’m going to dare to share a little perspective and some tidbits in the hope that it’s helpful.
With the current state of navigation, we can debate Here vs OSM, tracks vs routes, gpx 1.1 vs 1.2, etc.
There was a time when the world was flat and was lighted each day by Helios who drove a golden chariot across the sky from east to west. Later, the earth began to become round, although it wasn’t circumnavigated until Magellan sailed around it in the early 1500’s. Around the same time, Copernicus proposed that the sun was the center of the universe. Galileo Galilei advocated for Copernicus’ theory in the early 1600’s. That heresy caused him to spend his later years under house arrest. Back then, latitude could be determined from the stars if the night sky was clear but longitude was elusive until clockmaker John Harrison produced the marine chronometer in the mid 1700’s.
GPS didn't become operational until 1993 but wasn't available for civilian use in 1998.
Many of us, at least the older ones like me, used to find our way around with sometimes out of date paper maps.
Today we look at lines on a digital screen and think of them as physical roads. We look at a motorcycle icon on a SatNav and think of it as our current position. We have high expectations for modern electronics. In reality, none of it is exact, although most of it is close most of the time.
Below is a section of road according to a Here map (magenta line), and an OSM map (green line). I traveled that road tracking my position with a zumo XT2 (yellow line) and another GPS tracking device (blue line). Depending on tolerance, we might say that all four lines are “right”. We might also conclude that it is unclear whether any of them are “right”.
A SatNav calculates it position on a periodic (not continuous) basis from time signals sent by satellites. The number of dots on those lines depends on how frequently position is determined and recorded. More dots imply more precision, but that does not assure any greater accuracy. Under the best conditions, those positions are accurate within several feet (a few meters).
In some locations, these four lines might vary more significantly. The vast majority of the time, they are close enough to be useful. On the occasions when they vary enough to be confusing, I try to remind myself, if Magellan managed to figure it out, I probably can too.
Planning and then navigating with the same map, route preference and avoidance settings, and with software / devices using the same routing algorithms is, of course, most likely produce the most consistent results for us, but it’s not always that simple. For various reasons, one might want, for example, to plan with the MRA route planner and navigate with the Garmin zumo.
In the end, we each do what works best for us and adjust as we learn from our experience. There is no perfect answer that works for everyone every time.
A map is an attempt to project, onto a flat surface, the location of physical roads or paths that exist on a portion of the round earth. Modern maps are much better than the ones Magellan had, but they rarely perfect. They are often generated from multiple sources. A given source which is most accurate in one particular area might not be the most accurate in a different area. Here maps are based on multiple, licensed, professionally produced, and government maps. Garmin’s are supplemented with OSM map data [thus the inclusion of both copyright notices on the device info page of a zumo].
Zooming in on a digital map reveals that roads and paths are represented by straight lines.
Each end of each straight line is a point, although the points are typically not visible. It requires more points to represent a curved road and fewer points to represent a straight road. There are also points at intersections.
Separate from those, when we click on a map to specify our desired stops (via points) and and other points we’d like to pass thorough (shaping points) we create “route points". Routing algorithms use the map’s points at intersections to find the best path(s) between our specified route points. Once the route is determined, all of the map’s points along the route can be used to draw the route along the road or path.
If a track is generated from the route, all of the map’s points along the route become track points. If a gpx 1.2 route is generated, those same points become route point extensions (aka hidden or ghost points). Track points and route point extensions are the exact same points. They are formatted and treated differently however. Once generated, a track will never change. If a route is fully recalculated, its route point extensions are discarded – the route is re-calculated using only the available route points (via and, if available, shaping points).
As a result, after import to another device, an MRA exported:
- track, with its many track points, will provide a very accurate representation of the MRA generated route, but it is fixed in place.
- gpx 1.2 route with the user specified via points and the route point extensions matching the track points, will provide the same very accurate representation of the MRA generated route as long as it is not fully recalculated. Unlike a track, it can be amended, to some degree, to support a Closest Entry Point navigation [re]start or an off-route calculation to get back onto the route without triggering a full recalculation.
- gpx 1.1 route with the user specified via and [relatively few] shaping points, but without the benefit of the [many] route point extensions, contains a less accurate representation of the MRA generated route. It will always be subject to route calculation and variation wherever it is imported.
- gpx 1.2 route will be the least accurate if it is fully recalculated since only via points will be available to the routing calculation.
-
Being a new guy here, I’ve been mostly quietly following this discussion. I’m going to dare to share a little perspective and some tidbits in the hope that it’s helpful.
With the current state of navigation, we can debate Here vs OSM, tracks vs routes, gpx 1.1 vs 1.2, etc.
There was a time when the world was flat and was lighted each day by Helios who drove a golden chariot across the sky from east to west. Later, the earth began to become round, although it wasn’t circumnavigated until Magellan sailed around it in the early 1500’s. Around the same time, Copernicus proposed that the sun was the center of the universe. Galileo Galilei advocated for Copernicus’ theory in the early 1600’s. That heresy caused him to spend his later years under house arrest. Back then, latitude could be determined from the stars if the night sky was clear but longitude was elusive until clockmaker John Harrison produced the marine chronometer in the mid 1700’s.
GPS didn't become operational until 1993 but wasn't available for civilian use in 1998.
Many of us, at least the older ones like me, used to find our way around with sometimes out of date paper maps.
Today we look at lines on a digital screen and think of them as physical roads. We look at a motorcycle icon on a SatNav and think of it as our current position. We have high expectations for modern electronics. In reality, none of it is exact, although most of it is close most of the time.
Below is a section of road according to a Here map (magenta line), and an OSM map (green line). I traveled that road tracking my position with a zumo XT2 (yellow line) and another GPS tracking device (blue line). Depending on tolerance, we might say that all four lines are “right”. We might also conclude that it is unclear whether any of them are “right”.
A SatNav calculates it position on a periodic (not continuous) basis from time signals sent by satellites. The number of dots on those lines depends on how frequently position is determined and recorded. More dots imply more precision, but that does not assure any greater accuracy. Under the best conditions, those positions are accurate within several feet (a few meters).
In some locations, these four lines might vary more significantly. The vast majority of the time, they are close enough to be useful. On the occasions when they vary enough to be confusing, I try to remind myself, if Magellan managed to figure it out, I probably can too.
Planning and then navigating with the same map, route preference and avoidance settings, and with software / devices using the same routing algorithms is, of course, most likely produce the most consistent results for us, but it’s not always that simple. For various reasons, one might want, for example, to plan with the MRA route planner and navigate with the Garmin zumo.
In the end, we each do what works best for us and adjust as we learn from our experience. There is no perfect answer that works for everyone every time.
A map is an attempt to project, onto a flat surface, the location of physical roads or paths that exist on a portion of the round earth. Modern maps are much better than the ones Magellan had, but they rarely perfect. They are often generated from multiple sources. A given source which is most accurate in one particular area might not be the most accurate in a different area. Here maps are based on multiple, licensed, professionally produced, and government maps. Garmin’s are supplemented with OSM map data [thus the inclusion of both copyright notices on the device info page of a zumo].
Zooming in on a digital map reveals that roads and paths are represented by straight lines.
Each end of each straight line is a point, although the points are typically not visible. It requires more points to represent a curved road and fewer points to represent a straight road. There are also points at intersections.
Separate from those, when we click on a map to specify our desired stops (via points) and and other points we’d like to pass thorough (shaping points) we create “route points". Routing algorithms use the map’s points at intersections to find the best path(s) between our specified route points. Once the route is determined, all of the map’s points along the route can be used to draw the route along the road or path.
If a track is generated from the route, all of the map’s points along the route become track points. If a gpx 1.2 route is generated, those same points become route point extensions (aka hidden or ghost points). Track points and route point extensions are the exact same points. They are formatted and treated differently however. Once generated, a track will never change. If a route is fully recalculated, its route point extensions are discarded – the route is re-calculated using only the available route points (via and, if available, shaping points).
As a result, after import to another device, an MRA exported:
- track, with its many track points, will provide a very accurate representation of the MRA generated route, but it is fixed in place.
- gpx 1.2 route with the user specified via points and the route point extensions matching the track points, will provide the same very accurate representation of the MRA generated route as long as it is not fully recalculated. Unlike a track, it can be amended, to some degree, to support a Closest Entry Point navigation [re]start or an off-route calculation to get back onto the route without triggering a full recalculation.
- gpx 1.1 route with the user specified via and [relatively few] shaping points, but without the benefit of the [many] route point extensions, contains a less accurate representation of the MRA generated route. It will always be subject to route calculation and variation wherever it is imported.
- gpx 1.2 route will be the least accurate if it is fully recalculated since only via points will be available to the routing calculation.
gpx 1.2 route with the user specified via points and the route point extensions matching the track points, will provide the same very accurate representation of the MRA generated route as long as it is not fully recalculated. Unlike a track, it can be amended, to some degree, to support a Closest Entry Point navigation [re]start or an off-route calculation to get back onto the route without triggering a full recalculation.
gpx 1.2 route will be the least accurate if it is fully recalculated since only via points will be available to the routing calculation.
Your complete post above was a very good read. Well written.
In particular, the two GPX 1.2 pieces I quoted are gold for anyone wanting to understand it's behavior. In the nutshell, if you can avoid doing anything that triggers a complete 1.2 recalculation, the route should be a complete representation of the MRA route. The major trigger I found for complete recalculation is adding a via point as part of "Search" or "Up Ahead". As you stated, only via points will then be available for routing calculations, and your route will probably look very different from what you intended. There might be other offending actions, but I haven't found them -- yet. In my testing, Closest Entry Point navigation restart or an off-route calculation to get back onto the route do not harm the integrity of the route. That helped cement for me the value of 1.2.All my testing with 1.2 has been for testing/verification purposes only. I'm feeling good enough to give it a go on something more critical coming up.
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That would be brilliant. In my case it was trying to route me half way round the world to get back to the next via point when I didn't take the first turn.
That would be brilliant. In my case it was trying to route me half way round the world to get back to the next via point when I didn't take the first turn.
I got out today and tested 1.2 off-route recalculation with my older Zumo XT unit.
I found the behavior to be the same as what I experienced with my XT3. When I turned left on a side road from my main road route, the XT almost immediately recognized Off-Route, and prompted me for action. I pressed re-calculate, and the XT immediately tried to turn me around through a looping side street. I continued, and then the XT tried to get me to do a U-Turn. The XT was like a Pitbull on a bone.
I know how this story would continue, so I did a U-Turn and returned to the main road at the Off-Route entry point as directed, just like I did with the XT3. I get that this is just one scenario, and you may have encountered a different situation which triggered a different action.
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Thanks for that John its good to know that the XT is capable of navigating back to a GPX 1.2 route.
I tend to navigate in the opposite sort of way where I seek out the backroads and try to avoid the main roads and towns as much as possible. There's nothing I like more than riding up a road with grass growing up the Middle.
I had a look at the setup of my XT as stated earlier I haven't used it for actual navigation for over a year now preferring instead to use my phone connected to my Africa Twin's built in screen. The only thing that I can see that might have messed up the behaviour of the unit on test was the OSM mapping of Ireland I have on an SD card in the machine. This shouldn't mess up the rerouting if its disabled as it was on my XT but I think it should be eliminated from the inquiries.
I'll delete the mapping from the SD card and have a go again with GPX 1.2. Unfortunately that might be a few weeks away as I go next week to have a cataract removed and will be off the road.....for everyone's safety
I had another go at simulating the route but obviously you can't simulate going off route just adding an element to the route before the first turn. As expected GPX 1.2 routed past the new addition directly to the next via point.
Whereas the GPX1.1 version of the file was able to deal with it.
Thanks for checking that John. I look forward to having another go minus the OSM maps on the card......and when I'm safe to be let out!!
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