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IS GPX outlining of buildings common practice?

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  • dale.parson
    Hi. I am new to GPS and GPX. Is there typically a way to represent outlines of sizable buildings, for example a shopping mall, in GPX or any GPS format? It
    Message 1 of 11 , Jun 15, 2007
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      Hi. I am new to GPS and GPX. Is there typically a way to represent
      outlines of sizable buildings, for example a shopping mall, in GPX or
      any GPS format? It seems like ptsegType might be a way to represent the
      outline of a building, although it does not give elevation or height
      information that you could interpret as floors. I don't want to kludge
      something if there is a standard or de facto way to represent buildings
      and other constructs with area, non-rectangular outlines, and possibly
      height. Thanks.
    • Simon Slavin
      ... There are lots of GPS formats. I suspect that the sort of formats used by Goggle might have the sort of thing you re asking about. ... ptsegType in GPX
      Message 2 of 11 , Jun 17, 2007
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        On 15 Jun 2007, at 9:28, dale.parson wrote:

        > Hi. I am new to GPS and GPX. Is there typically a way to represent
        > outlines of sizable buildings, for example a shopping mall, in GPX or
        > any GPS format?

        There are lots of GPS formats. I suspect that the sort of formats
        used by Goggle might have the sort of thing you're asking about.

        > It seems like ptsegType might be a way to represent the
        > outline of a building, although it does not give elevation or height
        > information that you could interpret as floors. I don't want to kludge
        > something if there is a standard or de facto way to represent
        > buildings
        > and other constructs with area, non-rectangular outlines, and possibly
        > height.

        ptsegType in GPX 1.1 is very interesting. It appears to exist as a
        type but with no type that contains it: in other words no opportunity
        for anyone to use it. I've never thought about it before. It seems
        as good a way as any to outline an object.

        Simon.
      • Robert Lipe
        ... If you re trying to model building (you d mentioned internal heights of floors, so I suspect you want more than just a perimeter outline) GPX is probably
        Message 3 of 11 , Jun 17, 2007
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          > > Hi. I am new to GPS and GPX. Is there typically a way to represent
          > > outlines of sizable buildings, for example a shopping mall, in GPX or
          > > any GPS format?
          >
          > There are lots of GPS formats. I suspect that the sort of formats
          > used by Goggle might have the sort of thing you're asking about.

          If you're trying to model building (you'd mentioned internal heights of
          floors, so I suspect you want more than just a perimeter outline) GPX is
          probably the wrong tool for the job. Google has some widely accepted tools
          for building and rendering such thing including integration with Sketechup.
          I don't know about other similar products.

          http://earth.google.com/3d.html
          http://www.gearthblog.com/blog/archives/2006/09/high_quality_3d_buil.html
        • Andy Mabbett
          In message , dale.parson writes ... In drafting the proposed extension for the geo microformat:
          Message 4 of 11 , Jun 17, 2007
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            In message <f4usp0+jn36@...>, dale.parson
            <dale.parson@...> writes

            >Is there typically a way to represent outlines of sizable buildings,
            >for example a shopping mall, in GPX or any GPS format?

            In drafting the proposed extension for the geo microformat:

            <http://microformats.org/wiki/geo-waypoint-examples#The_Problem>

            I've wrestled with, but not resolved, the issue of perimeters, not only
            for buildings but for any polygon (a plot of land, county or country,
            for example).

            The issue - at its simplest - is; if I publish four coordinates, do they
            form a square, or the shape of a letter "U". In other words, how do I
            indicate that the route continues from point 4 back to point 1?

            Perhaps we need a fourth GPX type: after waypoint, track and route;
            polygon?

            --
            Andy Mabbett
            * Say "NO!" to compulsory UK ID Cards: <http://www.no2id.net/>
            * Free Our Data: <http://www.freeourdata.org.uk>
            * Are you using Microformats, yet: <http://microformats.org/> ?
          • Dan Foster
            Hello, ... You re welcome to look at how ExpertGPS stores polygon data in a GPX extension. http://www.expertgps.com/
            Message 5 of 11 , Jun 17, 2007
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              Hello,

              Sunday, June 17, 2007, 3:21:11 PM, Andy wrote:

              > Perhaps we need a fourth GPX type: after waypoint, track and route;
              > polygon?

              You're welcome to look at how ExpertGPS stores polygon data in a GPX
              extension.

              http://www.expertgps.com/

              http://www.topografix.com/GPX/gpx_overlay/0/3/


              --
              Dan Foster
            • Robert Lipe
              ... If point 0 == point 3 then it s a closed polyline and thus a polygon. That would make it a triangle if you have four points. It s a very common way to
              Message 6 of 11 , Jun 17, 2007
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                > The issue - at its simplest - is; if I publish four coordinates, do they
                > form a square, or the shape of a letter "U". In other words, how do I
                > indicate that the route continues from point 4 back to point 1?

                If point 0 == point 3 then it's a closed polyline and thus a polygon.
                That would make it a triangle if you have four points.

                It's a very common way to represent this.

                > Perhaps we need a fourth GPX type: after waypoint, track and route;
                > polygon?

                Remembering the goal of GPXs, I'm not sure I see a need for it in this
                context.

                Besides, we already have two primitives for representing polylines and a
                polygon
                is just a closed polyline.

                Look at KML, GML, Shape, or a large number of other existing formats that
                have
                already had to solve this.
              • Simon Slavin
                ... I don t know from microformats, but I have a problem with polygon in the GPX format. I think you re just trying to echo something that has been done
                Message 7 of 11 , Jun 17, 2007
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                  On 17 Jun 2007, at 8:21, Andy Mabbett wrote:

                  > In drafting the proposed extension for the geo microformat:
                  >
                  > <http://microformats.org/wiki/geo-waypoint-
                  > examples#The_Problem>
                  >
                  > I've wrestled with, but not resolved, the issue of perimeters, not
                  > only
                  > for buildings but for any polygon (a plot of land, county or country,
                  > for example).
                  >
                  > The issue - at its simplest - is; if I publish four coordinates, do
                  > they
                  > form a square, or the shape of a letter "U". In other words, how do I
                  > indicate that the route continues from point 4 back to point 1?
                  >
                  > Perhaps we need a fourth GPX type: after waypoint, track and route;
                  > polygon?

                  I don't know from microformats, but I have a problem with 'polygon'
                  in the GPX format. I think you're just trying to echo something that
                  has been done before in mapping systems. A polygon is an abstract
                  mathematical shape. It's a way of drawing a map, and if you're a
                  geek using map-drawing software it's fine there. It doesn't belong
                  on a map or in the real world: I've never been walking through a
                  forest and said "Look ! Over there: a polygon !".

                  In one way, what you're really doing is defining 'structure' (as in
                  artificial structure) or 'building' or something like that. That
                  suggests you're describing the perimeter of a thing above-ground
                  (i.e. a 'U' would take more than four points). In GPX it would
                  consist of a list of 'ptType', probably with a clockwise convention.

                  If you're going to do that, then there are two more things to
                  consider at the same time. The first is a body of water: it would be
                  useful to be able to describe the perimeter of a lake, a pond, or
                  even an artificial pool. The other is to describe an area that is
                  distinguished from the surroundings somehow. The most common type I
                  can think of is an area cordoned-off and marked 'dangerous' or 'no
                  trespassing' or something. Both of those things are similar to the
                  'polygon' you described above and if you support one you might as
                  well support them all.

                  Perhaps we need a tag with types, like <polygon type="water"
                  color="CCCCFF" ...>. Dammit, I can't think of a general word better
                  than 'polygon'.

                  The next question is whether it should be in GPX 1.2 or not. Right
                  now it could be an extension to 1.1. But is this type of thing
                  really part of what GPX is for, or is this part of a bigger thing ?

                  Simon.
                • Simon Slavin
                  ... Dan, this would have been very useful for me a few months ago but I didn t know about it. Referred to by it I see
                  Message 8 of 11 , Jun 17, 2007
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                    On 17 Jun 2007, at 11:06, Dan Foster wrote:

                    > http://www.topografix.com/GPX/gpx_overlay/0/3/

                    Dan, this would have been very useful for me a few months ago but I
                    didn't know about it. Referred to by it I see

                    <http://www.topografix.com/GPX/gpx_style/0/2>

                    which would have answered a question someone else asked on a usenet
                    group. Is there a list of all these things somewhere ?

                    Simon.
                  • dale.parson
                    Thanks for all the informed responses. This one prompts me to make my ... represent ... GPX or ... formats ... heights of ... GPX is ... accepted tools ...
                    Message 9 of 11 , Jun 18, 2007
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                      Thanks for all the informed responses. This one prompts me to make my
                      goals a little more explicit:

                      --- In gpsxml@yahoogroups.com, "Robert Lipe" <robertlipe@...> wrote:
                      >
                      > > > Hi. I am new to GPS and GPX. Is there typically a way to
                      represent
                      > > > outlines of sizable buildings, for example a shopping mall, in
                      GPX or
                      > > > any GPS format?
                      > >
                      > > There are lots of GPS formats. I suspect that the sort of
                      formats
                      > > used by Goggle might have the sort of thing you're asking about.
                      >
                      > If you're trying to model building (you'd mentioned internal
                      heights of
                      > floors, so I suspect you want more than just a perimeter outline)
                      GPX is
                      > probably the wrong tool for the job. Google has some widely
                      accepted tools
                      > for building and rendering such thing including integration with
                      Sketechup.
                      > I don't know about other similar products.

                      I had looked at Google SketchUp as a possible component of what I
                      need, but I guess the second half of my quest is to find existing
                      databases of GPS-oriented data, preferrably open source (if they
                      exist), that model hierarchical buildings/establishments, a shopping
                      mall being an easy example. Of course, some people are doing that
                      with Google SketchUp and attaching their creations to Google Earth.
                      But I had imagined that there might already be activity within the
                      OpenStreetMap project or elsewhere to capture this kind of data in
                      GPX, and therefore at least de facto common practices for
                      representing it in GPS-oriented data.

                      --- In gpsxml@yahoogroups.com, Dan Foster <egroups@...> wrote:
                      >
                      > Hello,
                      >
                      > Sunday, June 17, 2007, 3:21:11 PM, Andy wrote:
                      >
                      > > Perhaps we need a fourth GPX type: after waypoint, track and
                      route;
                      > > polygon?
                      >
                      > You're welcome to look at how ExpertGPS stores polygon data in a GPX
                      > extension.
                      >
                      > http://www.expertgps.com/
                      >
                      > http://www.topografix.com/GPX/gpx_overlay/0/3/

                      I helps to see another working solution to the problem. Thanks! I am
                      enough of a newbie not to have an opinion one whether new GPX
                      constructs are warranted. If there is sufficient object-composition
                      and object-extension capability to fill this need from a technical
                      perspective -- and there appears to be -- that leaves the issues of
                      1) agreeing on usage conventions so as not to come up with two
                      competing usages of those object-composition and object-extension
                      capabilities, and then 2) populating some databases, e.g., OSM or
                      otherwise, to add momentum. It appears from the replies to be part of
                      the work in progress.

                      Thanks again.
                    • Simon Slavin
                      ... Not that I know of, but I don t know much. The best and foremost project to attach buildings to maps is Google with its use of SketchUp for Google Earth.
                      Message 10 of 11 , Jun 18, 2007
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                        On 18 Jun 2007, at 4:35, dale.parson wrote:

                        > I had imagined that there might already be activity within the
                        > OpenStreetMap project or elsewhere to capture this kind of data in
                        > GPX, and therefore at least de facto common practices for
                        > representing it in GPS-oriented data.

                        Not that I know of, but I don't know much. The best and foremost
                        project to attach buildings to maps is Google with its use of
                        SketchUp for Google Earth. If you need anything more than an outline
                        at ground level, that's your best bet.

                        I know of systems used by archaeologists to plot the locations of
                        finds (including enclosures rather than just artefacts at a point).
                        They're all ad-hoc solutions and annoying to use: a decent mapping
                        system with polygons is as good as or better than anything I've seen
                        used in the field.

                        Simon.
                      • Dave Patton
                        ... You might be interested in this: http://www.opengeospatial.org/pressroom/pressreleases/732 -- Dave Patton Canadian Coordinator, Degree Confluence Project
                        Message 11 of 11 , Jun 26, 2007
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                          dale.parson wrote:
                          > Hi. I am new to GPS and GPX. Is there typically a way to represent
                          > outlines of sizable buildings, for example a shopping mall, in GPX or
                          > any GPS format? It seems like ptsegType might be a way to represent the
                          > outline of a building, although it does not give elevation or height
                          > information that you could interpret as floors. I don't want to kludge
                          > something if there is a standard or de facto way to represent buildings
                          > and other constructs with area, non-rectangular outlines, and possibly
                          > height. Thanks.

                          You might be interested in this:
                          http://www.opengeospatial.org/pressroom/pressreleases/732

                          --
                          Dave Patton

                          Canadian Coordinator, Degree Confluence Project
                          http://www.confluence.org/

                          Personal website - Maps, GPS, etc.
                          http://members.shaw.ca/davepatton/
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