Author: smathermather

My primary interest is in understanding ecological processes in a synoptic fashion. This has led me down a long study with Geographic Information Systems and Remote Sensing as they relate to ecology and biological processes.
GDAL

Reprocessing imagery with GDAL and BASH — and then cleaning up afterward

I show a simple example today of using gdal tools to change from raster to polygons with Bash.  That’s right.  Still no pythonista here.  I have poked ever so gently at the surface of ruby and rails recently, while watching another coder re-tune his brain to a new set of principles of least surprise. By the way, for my regular readers, please be patient with … Continue reading Reprocessing imagery with GDAL and BASH — and then cleaning up afterward

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Analysis, Database, PostGIS, PostgreSQL, SQL

What is the center line of a complex polygon? Routing Stream and Rivers

Continuing my posts on the centerline of a complex polygon (you can work your way backward from here), here’s it’s application to a riverine system (legend: light blue river, black centerline derived from routing through the skeleton of voronoi polygons from a densified stream bank set + the skipped skeleton bits in pink– read through the series if you if you don’t grok that explaination): Continue reading What is the center line of a complex polygon? Routing Stream and Rivers

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Analysis, ArcGIS, Database, PostGIS, PostgreSQL, SQL

Proper (ab)use of a database, contour interpolation using #postgresql #postgis #arcgis

Anyone who has been following along at home knows I don’t think much like a DBA.  Sometimes that’s good; mostly it’s probably bad.  In this post, I hope it will be interesting. The problem of the day is how to take engineering contours derived from breaklines, a lidar point cloud, and all the lot, and do a good job interpolating that to a DEM.  This … Continue reading Proper (ab)use of a database, contour interpolation using #postgresql #postgis #arcgis

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Analysis, Database, PostGIS, PostgreSQL, SQL

What is the center line of a complex polygon? Routing as the solution

I’ve had a series of posts (including this one) on finding the center line of a complex polygon– especially with an interest in finding the center line of streams and river bodies.  We have to give credit to my colleague Tom Kraft for solving the polygon centerline problem.  Tom struck upon the very elegant solution– derive the medial axis, and then use a few end … Continue reading What is the center line of a complex polygon? Routing as the solution

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Other

Independence– Free as in Freedom, part II

A friend of mine read my first post “Independence– Free as in Freedom” and said this: “awesome blog and great post. did jack respond?” My response: “Nooo.  I think I’m unknown in the ESRI world ….  But it was a heartfelt post.  I think Jack has changed the world, but recognize it has changed him.  I’m pulling for that organization to radically re-invent itself.  The … Continue reading Independence– Free as in Freedom, part II

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OpenStreetMap

Using OSM Nominatim to search for geographic objects

Just playing a little today.  I’m at Cleveland Give Camp today, working on a project for Ohio City Writers, a non-profit youth creative writing center.  I’m deploying some maps for the registration site, that will be filterable, using CartoDB as a host for the data.  As I don’t know what we’re going to filter, or where the page will go yet, I was trolling around … Continue reading Using OSM Nominatim to search for geographic objects

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GeoServer

Serving and filtering #GeoJSON from #GeoServer

The nice thing about setting up something like GeoServer, which is so feature rich, is when you need to pivot based on the demands of a new project, the technical infrastructure is already there, just waiting to be configured or turned on. The case today: feature services.  Someone wants to use my existing infrastructure in a new application.  I typically serve tile services.  One checkbox … Continue reading Serving and filtering #GeoJSON from #GeoServer

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Cartography, Other

WordPress Country Stats, a cartographers complaint

In the category of moderately new features in WordPress, I really appreciate the new WordPress Country Stats, with the nice touch of flags of the nations, and a map.  As an inveterate map snob, however, the map drives me crazy: Why?  Because choropleth maps are bad for showing count data, unless all the polygons are the same size.  Look at the map above– France and … Continue reading WordPress Country Stats, a cartographers complaint

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