Just a quick link to a post I found on installing pgRouting on Ubuntu: http://obsessivecoder.com/2010/02/01/installing-postgresql-8-4-postgis-1-4-1-and-pgrouting-1-0-3-on-ubuntu-9-10-karmic-koala/ Continue reading Nice post on installing pgRouting on Ubuntu
A while back, I had a (somewhat cryptic) post on OGC services and security. A couple months later, I saw this post on GeoSolution’s site on GeoServer security and the ins and outs of various options, from native to proxied security. It is quite a bit more nuanced than my own… . I recommend you read it, even if you don’t use GeoServer– it is … Continue reading #OGC Web Services and #Security
Leaflet, CartoDB, GeoJSON, and cross platform web map deployment. First some introductions: “Leaflet is a modern, lightweight open-source JavaScript library for interactive maps for desktop and mobile web browsers, developed by CloudMade to form the core of its next generation JavaScript API. Weighting just about 21kb of gzipped JS code, it still has all the features you will ever need for you web mapping needs … Continue reading Playing with new tools and old standards: GeoJSON, Leaflet, CartoDB across platforms
In order to build simple clients for the MapFish print service, we have to understand what the protocols are that are invoked and how they function. To do this we can read the MapFish Print Module Doc, and then modify and vamp from there. While I was going to joke that this would be an excellent cure for insomnia, the joke fell apart when I … Continue reading Building simple clients for MapFish — Underlying Infrastructure
I’ve been enamored with the GeoExt interface for grabbing MapFish based print services since I first saw it. It’s a slick little interface, and can even been extended for multi-page print layouts pretty easily, ala http://tinyurl.com/mapfishmultipageprint. But as I’ve started to give thought not to what an organization full of professionals needs but what a public interface should looks (and probably those interfaces for professional … Continue reading Ditching GeoExt– building simple clients for MapFish
In a further exploration of using PovRay to do fast calculation of Voronoi polygons, let’s look to a real stream system as an example. Here’s where the magic comes out, and where medial axes are found. Here’s the povray code: Continue reading Fast Calculation of Voronoi Polygons in PovRay– Applied
Yet further abuse to follow in the application of PovRay for spatial analyses– be forwarned… . Calculating Voronoi polygons is a useful tool for calculating the initial approximation of a medial axis. We densify the vertices on the polygon for which we want a medial axis, and then calculate Voronoi polygons on said vertices. I’ll confess– I’ve been using ArcGIS for this step. There. I … Continue reading Fast Calculation of Voronoi Polygons in PovRay
Today, I just show pictures of my process for filtering the medial axis of extraneous elements. I’ll let the pics tell the story for now: scale axis transform 3 scale axis transform 2 scale axis transform 1 previous post original Continue reading What is the center line of a complex polygon? New approach.
I didn’t remember that I had 4 previous post on this topic, but I’ve gotten a little obsessed with this problem– how to (with relatively little computational cost) kind the centerline of complex polygons, so we can extract flow lines from streams, label long complex polygons, easily generate the centerline parcel boundary line for river bound parcels, etc.. FYI, here are my 4 previous posts … Continue reading What is the center line of a complex polygon? (cont. again!)
Smathermather's Weblog 