[mapserver-users] SVG

[Allan Doyle]

Stephen Lime wrote:
> 
> Actually MapServer is having GML output added as we speak. Initially this will be available
> via the OpenGIS WMT interface but logically it could be added as query output as well. Since

You have to be careful with terminology. WMT is not an interface, it's
an activity that brought about the WMS interface. (WMT = Web Mapping
Testbed, WMS = Web Map Service).

That being said, WMS 1.1.0 [1] drops any pretense at being able to
return feature data, leaving that task for a WFS (Web Feature Service),
not yet a spec, but a discussion paper available at [2]. However, at the
same time, a WMS 1.0.0 [3] or 1.1.0 can return GML as part of a
GetFeatureInfo request.

The essential difference between a WFS and a WMS is that the WFS
presents a set of operations that make more sense for vector data and a
WMS presents operations that make more sense for raster pictures. I
think whatever foundation you lay for having MapServer return GML will
stand you in good stead to move to a full WFS implementation.

Furthermore, there are some implementations of WFS and WMS that are
really just different entry points into the same software with different
interfaces layered on top.

> you're talking raw data here it boils down to queries rather than full draws. I believe there are tools
> to move from GML to SVG but haven't played in that area at all.

Yes, there are some that have been developed for/by the US Census Bureau
[4]

[1] http://www.opengis.org/techno/specs/01-047r2.pdf
[2] http://www.opengis.org/techno/discussions/01-023.pdf
[3] http://www.opengis.org/techno/specs/00-028.pdf
[4] http://www.gmlcentral.com/tiger/


	Allan

> Steve
> 
> Stephen Lime
> Internet Applications Analyst
> 
> Minnesota DNR
> 500 Lafayette Road
> St. Paul, MN 55155
> 651-297-2937
> 
> >>> Zhou Xu <zhox at yeah.net> 08/19/01 09:11PM >>>
> I find a Perl SVG library at http://cs.nott.ac.uk/~jxm/SVG/iexplore.html, maybe useful for this thread.
> 
> On 2001-8-16 18:34:00, you wrote:
> >David Moffett wrote:
> >>
> >> I am thinking about adding SVG ( Scalar Vector Graphics ) to mapserver.
> >> My questions are:
> >>
> >> 1. Is someone already doing this?  There was some talk on the mailing in
> >> Oct 2000 but I  did not see a conclusion.
> >> 2. Is it a good idea?  I think it is since we would like to use it
> >> ourselves.
> >> 3. What approach would be best.  I have looked at the code and have some
> >> ideas but I am a far cry from an expert on mapserver.
> >>
> >
> >
> >I'm not aware of anything that has been started on this front yet, but
> >we've had lots of interest expressed to have MapServer produce vector
> >output (SVG being only one possibility).  So if any of these projects
> >takes off then it's the kind of additions that we might get involved in.
> >
> >Anyway, I think your idea is a good one, but I think it should be done
> >"the right way" in order for your work to be profitable in the long
> >run.  A bit like the kind of changes Steve did when SDE and OGR were
> >added, and which allowed the PostGIS guys to plug their driver with much
> >less efforts.
> >
> >Basically that would mean redesigning important parts of the rendering
> >code in MapServer (and likely some of the mapfile stuff too) to make it
> >less GD-centric and be able to deal with various types of output.  If
> >this is done well for the SVG case then other output formats such as
> >GML, Flash, etc. can be added with much less efforts.
> >
> >My 0.02$
> >--
> >------------------------------------------------------------
> > Daniel Morissette               morissette at dmsolutions.ca
> > DM Solutions Group              http://www.dmsolutions.ca/
> >------------------------------------------------------------
> >  Don't put for tomorrow what you can do today, because if
> >      you enjoy it today you can do it again tomorrow.
> 
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Allan Doyle                         http://www.intl-interfaces.com
adoyle at intl-interfaces.com