Archive for October 2006
Hobu just posted an insightful article on what makes open source projects healthy, with a good amount of introspection around several large open geospatial projects and the open source geospatial community. Since he doesn’t allow comments, I’ll just have to write another article… 
Howard’s analysis of how OSGeo can be the catalyst that pushes member projects to new levels of function is spot-on. I really hope that we (all of us) can work to ensure that his challenge is upheld. This will require considerable levels of community involvement. I know that there is a lot of cool stuff to do, but many OSGeo committees are really struggling with the size of the task at hand and could really use more help.
Speaking of cool stuff… the MapGuide Open Source PSC had our first meeting today. Most of it dealt with the kind of critical process definition work that needs to be done in a healthy open source project. Reflecting back on that meeting — apart from realizing how much of a disruptive effect I have on meetings, sorry all — I can see how hard it is going to be for the Autodesk folks on the committee to adjust to open source, but I can also see how hard they are trying. It will be difficult for us to meet all of Howard’s criteria for a health project, especially since there’s only one person on the committee that has extensive open source development experience, but we’re going to give it our best shot.
This brings up another point. I’d like to say that it’s great to have our open source angel in the background, guiding us towards health. Thanks Daniel M. His presense as a mentor is a huge benefit to the MapGuide project that would not have been realized without OSGeo and the incubation process. I remember initially that quite a few folks (myself included) didn’t feel that MapGuide and some of the other initial projects should have to incubate. I am now extremely glad that OSGeo has forced this; it really helps projects move towards the goals that Hobu has clarified.
-J
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Great news,
Tyler Mitchell, of “Web Mapping Illustrated” fame has been hired as the executive director for the Open Source Geospatial Foundation (OSGeo).
https://www.osgeo.org/content/news/news_archive/tyler_ed.html
This will allow for more focussed action in areas where it is difficult to proceed with purely volunteer effort.
-J
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Ack, this is my last post for a while, promise…
I’ve heard the term neogeography a couple times before, and most recently saw it on the High Earth Orbit blog (by way of Planet Geospatial) with a link to the new site called neogeography.net.
The thought that keeps popping into my mind when I hear this term is: Couldn’t they have mashed it up a bit more? Like, into “Neography”?
-J
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Late last fall, I was a “mostly happy” MapGuide 6.5 user and was beta testing (am I allowed to say that?) Autodesk’s new code base. I even knew exactly what it was going to be called… at least three times. Then Autodesk dropped a bombshell and announced that they were going to release MapGuide as open source.
That was almost a year ago, and in that time a lot has changed. MapGuide has changed its name twice more (MapServer Enterprise, and finally MapGuide Open Source / Enterprise), the Open Source Geospatial Foundation (OSGeo) was founded as a collaborative effort between a bunch of open source geospatial projects and generously funded by Autodesk, and the first three 1.0 releases of MapGuide Open Source have taken place.
Just as importantly, MapGuide has been taking steps to become a healthy open source project and graduate from OSGeo incubation. A code provenance review has been undertaken, most of the requirements of the incubation checklist have been met, and finally this week the MapGuide Open Source Project Steering Committee (PSC) has been formed.
You can see the provisionary makeup of the MapGuide PSC on the OSGeo website; these will be firmed up more after a couple IRC meetings. Basically, though, the PSC is formed of three Autodesk employees (Bob Bray - Chair, Bruce Dechant and Tom Fukushima) and three external members (Andrew Morsell of Spatial Integrators, Paul Spencer of DM Solutions Group, and myself) but the final number of members is not finalised. I am excited to participate in this committee, and look forward to guiding MapGuide (mmm word choice) along its path as an innovative, flexible, and fully functional geoprocessing server.
Along the way, both MapGuide and the FDO project (which is also forming its PSC and undergoing a code provenance review) have started to garner community support. I wrote about FDO a couple weeks ago, and since that time have been pointed to an interesting presentation that was given at FOSS4G by Mateusz Loskot and Frank Warmerdam on their experiences in building the PostGIS and GDAL Raster FDO Providers, entitled FDO, Street Vendors in the Cathedral. It’s worth a read. I have also heard rumours of some commercial/proprietary endeavours that will either be creating FDO providers or using FDO internally to provide access to geospatial data.
With MapGuide, solution providers such as DM Solutions Group, Spatial Integrators, Pacific Alliance Technologies, and Arrow Geomatics are providing solutions on top of the MapGuide platform (I’m sure there are many others from the activity on the mailing lists. If I missed you, feel free to leave a comment below with a link).
As well, DM Solutions has announced a commercial subscription-based support service for MapGuide Open Source called Premiere, has been actively involved in the development of a web-based authoring application called Web Studio which is included in recent releases of MapGuide, and is working on various other initiatives which will substantially improve the value of MapGuide Open Source.
To have DM Solutions in our corner is a great thing, but I would be happy to see other developers providing value by joining the MapGuide Open Source development team and helping to take it in directions we haven’t even thought of yet. I hope to see this come about in the next year as the MapGuide development process becomes more public and others see ways that they can contribute. In particular, if anyone would like to work on an open source geocoding or routing service for MapGuide, please get in touch with the PSC after we get some of the administration out of the way and a roadmap in place. I, for one, would love to hear from you.
Well, that’s all for tonight. See you again in a month or so… unless I find time to write that simple FDO/MapGuide build guide earlier.
-J
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Well, this has been sitting in my half-finished pile for a long time, so I figured I’d better polish it up and kick it out the door (I’m practicing for my kids). There are probably other sites that have documented this, but here’s my version.
Google’s KML format has some really strong styling elements built into it, similar to HTML/CSS. In a single <Style> tag, you can specify how points, lines, and polygons should display in the Google Earth browser. For instance:
<Style id="parcelNormal">
<IconStyle>
<scale>0.8</scale>
<Icon>
<href>http://maps.google.com/mapfiles/kml/pal4/icon56.png</href>
</Icon>
</IconStyle>
<LabelStyle>
<scale>0</scale>
</LabelStyle>
<LineStyle>
<color>ff4090ff</color>
<width>10</width>
</LineStyle>
<PolyStyle>
<color>00000000</color>
</PolyStyle>
</Style>
This allows you to define polygons, points, and lines, all referencing the same style definition. Definitely a space saver over having to define the style against each feature:
<Placemark>
<name>238 Franklyn St.</name>
<styleUrl>#parcelNormal</styleUrl>
<Point>
<coordinates>-123.938788334,49.1646409443,0</coordinates>
</Point>
</Placemark>
<Placemark>
<name>238 Franklyn St.</name>
<styleUrl>#parcelNormal</styleUrl>
<Polygon>
<outerBoundaryIs>
<LinearRing>
<coordinates>
-123.93904811,49.16434558280001,0
-123.939274779,49.16457225540001,0
-123.939105984,49.1646449658,0
-123.93924107,49.1647800536,0
-123.938876261,49.16493630590001,0
-123.938424057,49.1646143977,0
-123.93904811,49.16434558280001,0
</coordinates>
</LinearRing>
</outerBoundaryIs>
</Polygon>
</Placemark>
And this is what it looks like:
There is also a <StyleMap> entity that allows you to specify a style to apply when a feature is active and when a feature is inactive:
<StyleMap id="parcel">
<Pair>
<key>normal</key>
<styleUrl>#parcelNormal</styleUrl>
</Pair>
<Pair>
<key>highlight</key>
<styleUrl>#parcelHighlight</styleUrl>
</Pair>
</StyleMap>
Unfortunately, the only feature type that triggers this normal/highlight switch is the point:
The secret to working around this is to provide a point feature as part of every line or polygon Placemark that you want to be affected by a mouseover. Then, when the user hovers over the point, the line or polygon is affected by the stylemap that applies to that composite feature. The key to doing this is a “wrapper” called MultiGeometry. MultiGeometry allows you to have multiple geometries tied to a single feature. For example:
<Placemark>
<name>238 Franklyn St.</name>
<styleUrl>#parcel</styleUrl>
<MultiGeometry>
<Point>
<coordinates>-123.938788334,49.1646409443,0</coordinates>
</Point>
<Polygon>
<outerBoundaryIs>
<LinearRing>
<coordinates>
-123.93904811,49.16434558280001,0
-123.939274779,49.16457225540001,0
-123.939105984,49.1646449658,0
-123.93924107,49.1647800536,0
-123.938876261,49.16493630590001,0
-123.938424057,49.1646143977,0
-123.93904811,49.16434558280001,0
</coordinates>
</LinearRing>
</outerBoundaryIs>
</Polygon>
</MultiGeometry>
</Placemark>
As you can see, both the point and the polygon are affected:
This trick is useful for those hand-crafting their KML, but it is also possible to build this kind of construct in some of the KML generating tools out there. For instance, in Safe Software’s FME, you can generate a point at the centroid of a polygon with a CenterPointReplacer, and then merge the polygons and their centroids using an Aggregator before writing this out into KML format (pdf). You can even generate the StyleMap elements (see format docs for details). In MapGuide Open Source, I use the GetPointInRegion() method to determine the centroid of the polygon, and build my MultiGeometry from this and the polygon coordinates. Most other GIS software has similar functionality.
The final example shown here is available for download in KML, XML and TXT formats.
-J
