[OSM-dev] Thoughts on an enhanced GPX api

[Martin Koppenhoefer]

2009/7/29 Richard Fairhurst <richard at systemed.net>:
> Martin Koppenhoefer wrote:
>> (b) potlatch? You can't move the aerial-layer (AFAIK)
> Yes you can - hold space and drag.

cool. Even better (but not for Potlatch alone, would be cool for JOSM
and OSM in general) would be to store this offset, and deliver/display
already corrected pictures. In the end although we can technically use
other WMS-Servers, we will generally all use yahoo.

>> you can't zoom in closely
>
> Yes you can - up to zoom 19. If you need more than that for tracing then you
> must have professional survey-grade GPS equipment and be walking very
> carefully down the centreline of each road.

the problem is, that on higher and highest zooms the background images
(yahoo) disappears (get grey and say: not available), so nearly nobody
would use it in my area at those zooms. You can actually see this in
my area by viewing the edits.
It's not that I'm using a highperfomance GPS but that I find it more
convenient and less exhausting to zoom in quite a lot. This permits to
draw/verify smooth curves, relative positions of different objects in
detail, constant distances of parallel ways, etc. even when the
absolute position might be less correct.

>> and it takes ages to load just the mapdata
>
> No it doesn't - it's on average faster than the equivalent .osm file for
> first download, and faster still on subsequent pans because it doesn't
> redownload already-loaded ways (unlike the map call).

Actually after some pans it stops to download at all (OSM), I click on
"view" (close potl) and than restart again on "edit" to overcome.
Please keep in mind that the network connectivity might be different
on a client in the UK and one in Italy (dependant on the provider,
backbones, etc. - although I have a DSL 6000-line). I would really
love to demonstrate you this effect - give me a ring when your in
Rome. Some time I was waiting 5-10 minutes and nothing happened any
more.

> If you try to edit central Karlsruhe at full-screen z13 on a 30in monitor,
> then yes, of course it'll take ages. ;)

I'm always zooming in as long as the imagery is visible (at Rome, not
KA), and my screen is small (1200x768). Btw: I find that there is a
problem what you might call a feature: you can already start to draw
whilst it is still loading. This results frequently in duplicate ways
drawn by users who thought there wasn't a way where there actually
already was.

>> not to talk about gpx-traces from the server

> Potlatch also has a very competent function for directly converting a GPS
> trace to a way, with in-built Douglas-Peucker simplification.

well, I personally don't like automatic conversion at all, but I
neither dislike others using it - as long as they don't use automated
simplication on the ways of other users.

Cheers,
Martin