[ka-Map-users] Drawing lines dynamically on top of kaMap

David William Bitner bitner at gyttja.org
Fri Sep 15 18:09:12 EDT 2006


Walter Zorn (don't have the web link handy, but it will be the top of a web
search) is the library that many folks have used for things like ruler
tools.

On 9/15/06, Stephen Woodbridge <woodbri at swoodbridge.com> wrote:
>
> ramesh karra wrote:
> > Thank you very much for the quick response stephen! I
> > will look into the archives.
> >
> > I have a quick question -
> >
> > What is the most efficient way to do this if the
> > number of points is small (say < 30).
>
> I think some people have mentioned doing it in javascript. I forget
> which library, but one of them has some basic line drawing capabilities.
> I think you will find it in the archives, or someone else might respond
> to this thread.
>
> -Steve
>
> > Thanks
> > Ramesh
> >
> >
> > --- Stephen Woodbridge <woodbri at swoodbridge.com>
> > wrote:
> >
> >> ramesh karra wrote:
> >>> Hi,
> >>>
> >>> Currently, I can successfully display a map
> >> generated
> >>> from a map file using mapserver and kaMap.
> >>>
> >>> I would like to know what is the best way to draw
> >> a
> >>> dynamic line(or route) as a layer on top of this
> >> map
> >>> given that the data I have is a sequence of points
> >>> represented by lattitude and longitude (and not in
> >>> some shape file or postgres db)
> >> Ramesh,
> >>
> >> There has been a lot of discussion on this, you
> >> might want to search the
> >> archives. To summarize, there is no good way to do
> >> this on the client
> >> yet. You can do it for a few line segments, but
> >> performance rapidly
> >> degrades to unacceptable as you start pushing over
> >> about 50 points.
> >>
> >> I think what a lot of people, well those that have
> >> actually implemented
> >> something are doing it server side. The scenario is
> >> as follows:
> >>
> >> 1) put your points into a session storage
> >> 2) modify the client to request a route image on
> >> viewport extents change
> >> 3) have a php, or cgi script read the session data
> >> and the viewport
> >> extents and scale and generate an image that is
> >> returned to the client
> >> 4) have the client pin the image to the viewport.
> >>
> >> This is basically the way that google is doing it.
> >> You can get a little
> >> bit smarter on the client to not make requests when
> >> the view port
> >> extents change if you don't need to redraw the
> >> image.
> >>
> >> -Steve W.
> >>
> >
> >
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-- 
************************************
David William Bitner
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