Thanks for posting that. Interesting.
A coluple of Points of information. I can only comment from using the Explore App, but since they use the same data, I suspect that what I'm about to say is relevant.
1. when you create a route /track on the Explore site, it will be a series of straight lines. When it is received by the Zumo, it is converted into a route that follows roads. I noticed that the shape was broadly similar once converted, and it seemed to pass through the places where my straight lines route changed direction - the corners.
Pics and comments here P61 and P62
app.php/ZXT-P61
2. Waypoints are saved places on the map. We are used to Wapoints being included as part of a route in Basecamp. They are not, in Explore. They just sit there on the map, looking pretty.
This is because in Basecamp, when you create a waypoint, the definition is placed in the gpx file as a separate group of statements.
When the waypoint is put into a route in Basecamp, the coordinates name and other details are copied into the route instructions, and it is set as either a via or a shaping point So the identical point appears twice in the gpx file. Once to declare it as a Waypoint, one to declare it as a point in the route. In Explore it is not declared as a point in a route only as a Waypoint.
So I guess that in Tread, which from what I have read, accesses the Explore database, that the route is being processed as described in section 1 of this answer. Making the route plotted as straight lines, fit the roads on the map.
The waypoints are probably undergoing lookup checks to see what is near the coordinates. Maybe being moved 'Oh he meant Sainsbury's car park' sort of thing.
I think that you may be expecting the Waypoint to be part of the route. But the last time I checked, the Waypoints and the route / track are two completely separate items. That is consistent with Garmin's definition of a Waypoint.
Let me know if that makes sense - or if it doesn't. I have never set eyes on an XT 2 or tread. I may be talking boll-twoddle.
If I may be permitted to add another thought to this monologue.....
I have suspected that Garmin in being by market forces. People are using all kinds of Apps to create routes - partly perhaps because Basecamp is too clever by half for many of its users - designed to use with all kinds of navigation devices, and employ a proper relational database structure.
So instead of accurate point placement being key to a good route, users are turning to hand held devices for their route planning. Big fingers, small screen, sunlight glare, different map products are not consistent with placing points accurately on a map.
So perhaps a 'fuzzy logic' is being employed so that the zumo has a chance of getting a route that actually follows the road that it thinks would be the user' intention.
Perhaps Zumo thinks - "This isn't on a road, where is the nearest road consistent with being between the next and previous point ? Here. That will do. "
or
"This isn't a proper place, what is this doing here. Maybe he meant 'Sainsbury' thats just over there."
The first thought, I think that I have seen in action. Via point, via point, via point. All placed accurately in roads in the Zumo itself. The middle via is placed deliberately to keep the route off the main dual carriageway. Use the Zumo trip planner to change that to a shaping point, and the point is moved and renamed to correspond with its new position. In this case it moves to the start of the dual carriageway that I was wanting to avoid. From other observations, it seems to move it onto the faster route between the two adjacent via points.
The second thought maybe. The behaviour is more of a supposition based on the fact that route points set and named in Basecamp are altered when they appear in the Zumo. it is as if the coordinates are being used to fuzzy-match a known location. That location is then used in the route. This behaviour seemed to start when I got my 595, when the Foursquare database was introduced. Just an observation, which may or may not be related. Changed point names often have the county name added to the location - eg WYK for West Yorkshire. I didn't know that we had 3 letter county codes until I saw this!
