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

Stephen Woodbridge woodbri at swoodbridge.com
Fri Sep 15 17:43:13 EDT 2006

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.


> 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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