[OSM-talk] Slippy map suggestions

[Christopher Schmidt]

On Mon, Dec 04, 2006 at 01:22:43AM +0000, Robert (Jamie) Munro wrote:
> Christopher Schmidt wrote:
> > On Sun, Dec 03, 2006 at 08:32:37PM +0100, Jonas Svensson wrote:
> >> On 3 Dec 2006 at 13:10, Christopher Schmidt wrote:
> >>
> >>> On Sun, Dec 03, 2006 at 03:51:47PM +0100, Jonas Svensson wrote:
> >>>> A couple of suggestions for the slippy map:
> >>>> 2. Show current zoom level and position for the middle of the shown 
> >>>> image.
> >>> Why 2? (Depending on the why, the implementation may be different, which
> >>> is why I ask.)
> >> Mostly to be able to create bookmarks for myself and to be able to 
> >> send to others. It's a lot easier to give such details or a URL to 
> >> someone than describe how to get there in terms of move right so-
> >> and-so much and so on...
> > 
> > The "View" tab at the top of the page is a link to the current view -- a
> > 'permalink', if you will. 
> 
> I once found this by mistake. I don't think it's clear enough. The word
> Permalink written small, like on http://labs.metacarta.com/osm/ I think
> is much clearer.

This can be achieved with:

  map.addControl(new OpenLayers.Control.Permalink());

> Even with a permalink, it would still be nice to have the lat-lon
> written of the center of the screen (or the mouse pointer), perhaps in
> the position where http://labs.metacarta.com/osm/ says "Last Update",
> just so that you know that you are looking at the real world, with real
> numbers that change. 

I've added both a bounding box for the current view (so that you can
then open it in JOSM or the like) as well as a MousePosition above it
which tells you where you're looking. I think that I have now crammed
every piece of information that I could possibly put into the page into
the 10px around all the edges.

(Note that when I say "I've added", I'm implying 'to
http://labs.metacarta.com/osm/ ', since that's the page I control.)

> When in the UK, it would be nice to see OS Grid
> coordinates as well, and similar for other countries with their own
> systems, although I guess writing a co-ordinate conversion routine in
> Javascript might be hard.

Converting the coordinates isn't hard. Converting them to something
useful to everyone is. If OSM is targeting being a global project
(rather than  UK one as it was, mostly, for quite a while) then I think
that using OS Grid coords is probably not the best idea.

I think a lat/lon is the right way to go here, until we have
openstreetmap.co.uk :)

> Another thing that would be useful is a graphical scale thing - one of
> those little rulers with miles on the top and km on the bottom. The
> thing that says "1 : 108K" isn't that useful IMHO.

That's there because I'm doing cartography with the map :) it's
extremely useful when you're trying to determine which features should
show up at which zoom: for example, since I know that zoom level 13 is
1:14k, I can safely turn on a feature at 1:10000 and down, or I know to
create a smaller railway station at 1:20k and up. You're right that it's
not useful for determining the scale of the map, but when you're
comparing to a 1:50k or 1:24k map, it's good to have that sense of
comparison available.

Code to make a scalebar in OpenLayers exists, sort of, but it requires
some improvements before it can be brought into trunk. If anyone has
javascript hacking skills, the code is available in
http://trac.openlayers.org/ticket/24 , along with a description of the
problem with the current code.  

(I don't personally have an interest in the scalebar, so you probably
won't see me implement it.)

Regards,
-- 
Christopher Schmidt
MetaCarta