Smathermather's Weblog

Remote Sensing, GIS, Ecology, and Oddball Techniques

Archive for the ‘FOSS4G 2011’ Category

Motivations behind Open Source

Posted by smathermather on September 20, 2011

Waxing philosophical tonight.  Apologies in advance.

Paul Ramsey had a great opening keynote opening keynote at FOSS4G on the business model/economics (punchline: business tactic) behind Open Source software, and Free and Open Source companies.  It was funny and convincing, began with absurdity, and made me laugh, as did his PostGIS for Power Users.  His presentation style is at once casual, clever, and passionate.  What caught my attention was the series of slides about the primary and secondary motivators behind making Open Source software: money, community, shared accomplishments, etc.  Is money or should money be the primary motivator behind Open Source software development?  I don’t mean for individual companies– for companies, money may be the primary motivator (if I may divorce individual choices from corporate motivation).  But for individuals working in the Open Source Geospatial community?

If RSAnimate’s video on “The surprising truth about what motivates us

(go ahead, watch it, I’ll wait) is a good indicator of what current research indicates motivates people, money becomes secondary once a certain level of comfort is met, and above that line (whatever that line is) more money actually makes us less productive, more risk averse, and well, less smart, of all things.  So, if Open Source is the superior development model, and we want great Open Source, do we want to be driving the model for Open Source development through the idea that money is the primary motivator for that development?  Money is important, and we want companies to understand that there are business models that include Open Source code as a tactic, but shouldn’t we be articulating carefully who we are and why we have the community, the tribes, of Open Source GeoSpatial developers and users we have?

So those intangibles Paul mentions in his keynote:

  • community
  • shared accomplishments
  • satisfaction of learning and exploring
  • freedom to build
  • membership in a global community

I argue those are the important factors in motivating great FOSS development.  The money.  That pays the bills, feeds the family, keeps the roof over out heads, etc., all vitally important.  But it’s the participation in projects larger and more important than me, the shared accomplishments, the great features and information I can provide to the public, it’s all these things that make this more than a job.  That’s what switches work from vital to integral.  Money can be made in many ways.  Which ways one chooses, that’s what distinguishes jobs from passions.  FOSS is great when it is our passion.

Posted in Conferences, FOSS4G 2011 | Tagged: | 2 Comments »

What is the center line of a complex polygon?

Posted by smathermather on September 16, 2011

Sat in on a great presentation yesterday by Tim Schaub and Justin Deoliveira on GeoScript. Definitely check out their tutorials. To practice what I learned, I thought I’d apply it to the problem of how to find the centerline of a polygon.

What do I mean by the centerline of a polygon? Well in the case of a stream that is drawn with both it’s banks, the centerline of a polygon is the effective flowline. Also, if you want to label such polygons, it would be useful to be able to calculate this. This could apply to road polygons as well, or labeling complex parcels, etc. etc. At first (and second) blush, there is no trivial solution. However, there are some excellent approximations.

There are some nice articles online about the derivation of centerlines from polygonized roads, e.g. this one. The basic approach is to densify the lines (if necessary), and run a Thiessen (Voronoi) algorithm, then grab the middle line from those polygons. So, let’s start this process, and take it through at least to deriving the Voronoi result using python/GeoScript:

First our stream line:

>>> from geoscript.geom import *
>>> from import *
>>> from geoscript.render import *
>>> poly = Polygon([(2130394.00006841,633268.4901058), ...

Then to view it quickly:

>>> draw(poly, format='mapwindow')

Maybe fly with a little style:

>>> style = Stroke('blue', width=1) + Fill('#0000ff', opacity=1)
>>> draw(poly, style, format='mapwindow')

Ok, now that’s a complicated enough polygon. What do we get from calculating a Voronoi diagram against it?:

>>> polyv=voronoi(poly)
>>> draw([polyv, poly], format='mapwindow')

See the centerline running through the stream? It’s not perfect, but apply some densification before we calculate the polygons, then select only that centerline, and Bob’s your uncle, you have a very nice stream centerline for flowline calculations, labeling, what have you. In future steps, I’ll set this up to extract that line as well, and perhaps host it as a WPS service on GeoServer. If I can (I’m not sure the limitations to GeoScript, have to bug the GeoScript guys today…), I’ll also use it to extend the labeling capabilities for my GeoServer instance without having to dig deep into Java development. Ah, I do love a good API.

Posted in Conferences, FOSS4G 2011, GeoScript, GeoTools | Tagged: , , , , | 8 Comments »

FOSS4G 2011 Denver– Ideal schedule

Posted by smathermather on August 19, 2011

I spent a few hours winnowing down my list of desired talks at FOSS4G and came up with the following list. Path dependence (i.e. technologies related to the ones I’m already deploying) were at the top of this list, but I do hope to expand my knowledge of all the options as well. For almost every slot, there were anywhere from 2 to 4 presentations that really excite me. And finally, one of the most exciting (to me) presentations is the last in this list (Lifemapper Moves Forward: Bringing Together Geospatial and Biodiversity Informatics Tools to Save the World)– which I’ll miss because I’ll be flying out at that time. Alas, I’ll have to download the presentation when I get back to Ohio.




Sept 13th

Developing OGC Compliant Web Applications With GeoExt

Andreas Hocevar

Sept 14th

State of PostGIS

Paul Ramsey

PostGIS 2.0, the new stuff

Regina Obe, Leo Hsu

Functional Coverages

Gennadii Donchyts, Deltares Fedor Baart

Tutorial: GeoServer Scripting with Python and RESTConfig

David Winslow

Introducing GXP: Webmapping made easy

Bart van den Eijnden

GeoScript – Spatial Capabilities for Scripting Languages

Justin Deoliveira, Jared Erickson

Scripting GeoServer with GeoScript

Justin Deoliveira, Tim Schaub

Sept 15th

Open Source tools for digital field mapping

ing Andrea Antonello, S.r.l., ing Silvia Franceschi

OpenLayers Mobile

Tim Schaub, Eric Lemoine

LiDAR Point Cloud Processing with libPC and libLAS

Howard Butler, Michael Gerlek

A web-based PostGIS educational tool

Javier Morales

The status of GeoServer WPS

Andrea Aime

Tutorial: Working with GeoScript

Tim Schaub, Justin Deoliveira

Sept 16th

HTML5 for Rich Geospatial applications on the web

Javier de la Torre

PostGIS Replication

Steven Singer

Store, manipulate and analyze raster data within the PostgreSQL/PostGIS spatial database

Pierre Racine

Once upon a time: JGrass

ing Andrea Antonello, HydroloGIS s.r.l., ing Silvia Franceschi, HydroloGIS

Lifemapper Moves Forward: Bringing Together Geospatial and Biodiversity Informatics Tools to Save the World

Aimee Stewart

Posted in Conferences, FOSS4G 2011, Other | Tagged: , | Leave a Comment »


Get every new post delivered to your Inbox.

Join 645 other followers