[talk-au] Snapping Major regional roads to GPS traces

[Little Maps]

Hi all, there’s a good primer on how to use the image offset database in JOSM here…

https://learnosm.org/en/josm/correcting-imagery-offset/

Bob, I doubt that the existing offset database will help you in central Qld, as there probably aren’t enough mappers who have used it in that region. I’ve tried to use the database in south-central NSW and I’ve never come across a saved offset for any imagery. If you don’t have an accurate base map like the NSW base map available, then, in the absence of any absolute measure of location accuracy, it’s difficult to know which imagery is best aligned, so you can’t really move the imagery and then upload the offset as you don’t know how good it really is. Vicious circle.

I’ve found the Strava heat map a really useful overlay for aligning imagery as the number of users (and hence traces) can often be orders of magnitudes greater than that in the OSM gpx collection. To clarify, I don’t use it to map anything but instead use it to align the available imagery and then map from the imagery. But, once again, in very remote areas even this source may not provide much useful data.

Cheers Ian

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstreetmap.org/pipermail/talk-au/attachments/20210516/a104b976/attachment-0001.htm>