OpenGIS mapping

[imap at chesapeake.net]

Rob,  Where are the specifications for the OGIS server?
Yes, that is a goal we should be working towards...  
I'd like to at least read up on it and see what kind
of problems we can identify.

Maybe Doug Nebert, or someone else on the list can
give some feedback about the getting mapserver working
in with the OGIS Web Mapping testbed apps.

On the issue about aspect ratio, most a map server
software will adjust to best fit and meet the input bb
args. I make the assumption that the algorithms for
adjusting the aspect ratio will vary.  Is there is a
published specification for doing that?

Regards,

Chris

Rob Atkinson wrote:
> 
> FYI
> 
> The current behaviour, which is to create the smallest possible extent
> that includes, and is centred on,  the requested extent and conforms to
> the aspect ratio of the image, is as specified in the OpenGIS Consortium
> Web Map Server specification.
> 
> A perl wrapper for mapserv to conform to the OGC specification is under
> construction. We'll be putting it up on  public CVS site as soon as we
> can.
> 
> Steve, I have asked this before - is it possible, and can you provide an
> example, of specifying the projection to be used from the CGI
> parameters?
> 
> Future plans include actually parsing the .map file to create the
> "Capabilities Document" in XML required for OGC conformance. (Its
> currently hand built)
> 
> Also, a modified version of the mapimage Applet that uses the OGC
> protocol to get a base map and allows Javascript control of the extent
> to fetch will be posted. Just need to check the copyright on the
> original code to see if this is OK.
> 
> The community will be free to take these and modify them further.
> 
> Regards
> 
> Rob Atkinson
> 
> Frank Lochter wrote:
> 
> >  Hi Steve,
> > I have a small problem and would like to discuss this here.
> >
> > 1. When I specify a bbox (lat, lon), then the result map should  fit
> > exactly within this BBox.
> > 2. When I specify a width and height, the result bitmap should have
> > this width and height.
> > 3. What is when I specify bbox and width and height? Then something is
> > over defined!
> >     - I assume, the result should exactly fit in the bbox AND the
> > bitmap should fit exactly in one
> >       dimension width or height and the other dimension of the bitmap
> > should be calculated
> >       on the fly!
> > - I get something unexpected when the map server extracts the bbox,
> > especially when I
> > like to integrate the bitmap into an other application and assume,
> > that the bitmap has the
> > bbox, that I used to generate it.
> >
> > Is there any way to get what I assume in 3. !
> >
> > Sincerely
> >
> > Frank Lochter
> >
> > Stephen Lime wrote:
> >
> >> Yup, the extent is recaclulated based on the shape of the extent and
> >> the window
> >> size/shape. You are gauranteed to see the whole extent plus a bit
> >> more. The
> >> algorithm fits your requested extent in either x or y dimension
> >> (whichever fits
> >> best) and then pads the other dimension as needed. This has to be
> >> done in
> >> order to get the right map to image transformation. You wouldn't
> >> necessarily
> >> have to actually display data outside the actual requested extent
> >> but that would
> >> result in a great deal of blank space in the resulting image, so the
> >> computed extent
> >> is used to select/clip data.
> >>
> >> Steve
> >>
> >> Stephen Lime
> >> Internet Applications Analyst
> >>
> >> Minnesota DNR
> >> 500 Lafayette Road
> >> St. Paul, MN 55155
> >> 651-297-2937
> >>
> >> >>> Ralf Puchert <puchert at gfz-potsdam.de> 03/16/00 10:33AM >>>
> >> Hello,
> >>
> >> When we use
> >>
> >> http://130.
> >> 1.52.178/cgi-bin/mapserv?mode=map&layer=elevation&mapext=
> >> -180+-10+180+90&map=/var/mapserver/global/global.map&mapsize=500+250
> >>
> >> the outputmap has the wrong southernmost latitude.
> >> It seems to be that something is overdefined.
> >> Will the produced map whithin geographic coordinates expanded
> >> to the width and height values of the bitmap or
> >> will the geographic bounding box be recalculated ?
> >>
> >> Sincerely
> >>
> >> Ralf Puchert
> >
> > --
> > Dr. Frank Lochter
> > Data Centre
> > GFZ Potsdam
> > Telegrafenberg A3
> > 14473 Potsdam
> > fon. +49-331-288-1701
> > fax. +49-331-288-1703
> > url   http://www.gfz-potsdam.de/~marco
> >
> 
> --
> _______________________________________________________________
> Rob Atkinson                        Email: rob at socialchange.net
> Director
> Social Change Online         Mob: 0419 202 973
> 6A Nelson Street                       Tel: +61 (0) 2 9557 6500
> Annandale NSW 2038                     Fax: +61 (0) 2 9519 8940
> Sydney, Australia       WWW: http://online.socialchange.net.au

-- 

Chris Stuber (mapsurfer)
Silicon Mapping Solutions, Inc.
410-257-3187