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#1 2007-05-06 21:48:06

Tony Q
Registered: 2007-03-26
Posts: 26

Is an approximation to a road/track worth including?

I've been wondering over the past week or two about what to do when I have one or two GPS tracks over a path or road that carries little traffic.  Should I attempt to plot the path or road or not?

Clearly, from only one or two tracks, there is considerable uncertainty in the data.  However, perhaps it's a footpath that I had one chance to walk down, and which I know to be little used, and where I know I won't have another chance to walk it.  Should I plot the data or not?  If I do, then it's very likely that the resulting path on the map will be somewhat inaccurate; if I don't, then it'll be missing completely.

Where major roads are concerned, I think it's fairly clear that one waits until there's sufficient data that can be downloaded.  For smaller roads, however, this may take a long time.  For footpaths it may never happen.  So presumably it's better to have a somewhat inaccurate representation on the map (and if more data becomes available, someone can correct it) rather than having nothing.

Is that the right sort of approach?



#2 2007-05-07 07:17:56

From: Glasgow
Registered: 2007-04-28
Posts: 9

Re: Is an approximation to a road/track worth including?

My (admittedly very newbie) opinion is that you would be better to plot the track even if somewhat inaccurately. As long as it is topographically correct, it should not cause anyone grief, assuming it doesn't run along the edge of a precipice. As you say, it can be improved with time. That's the benefit of a community wiki approach to mapping.
I would be interested to hear any counter arguments as this is the approach I would take (while striving for maximum accuracy wherever possible).

Mapping tools: Garmin GPS 60, pen & paper, iRiver iFP-899, Brompton L3, Thermos


#3 2007-05-07 08:28:01

From: Apeldoorn (NL)
Registered: 2007-03-17
Posts: 3,269

Re: Is an approximation to a road/track worth including?

I think the majority of roads have initially been mapped using a single tracklog only. There is absolutely no harm in having a road with an offset at first, as more traces become available the exact position can be determined in a later stage.

Topology is more important though: e.g. if two roads intersect to a third with a slight offset then that offset should be mapped as such. In this situation it doesn't matter if the offset position isn't correct, it just has to reflect the actual situation. A navigation application can then produce accurately hints, like: "At the next intersection go left and after 10m go right.".

Mapping tools: Garmin GPSmap 60CSx, Giant Terrago 2002


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