web development

Mapping GISPs Again With Leaflet.markercluster

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So I’ve been playing with Leaflet a lot lately. It’s become my lightweight mapping library of choice. There’s a lot it doesn’t do so I keep OpenLayers and others in the rotation as well but Leaflet is direct and to the point so I use it when I can.

Click the image to go to the live demo

A while back, I stumbled onto the Leaflet.markercluster project on GitHub, which adds a clustering layer type. I wanted to try it so I revisited my old GISP heat map demo (Silverlight) and decided to rework it. I was happy to finally get a chance to strip out the plug-in, anyway.

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CartoDB/Leaflet Sample Update

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A while back, I posted about some experimentation I did with Leaflet and CartoDB in the wake of FOSS4G in Denver. I recently had the chance to go back and update that sample with some spatial queries. At the time of the original post, CartoDB was still in beta and spatial queries didn’t seem to work, despite the fact that the back-end was driven by PostGIS.

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CartoDB + Leaflet = Easy

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One of the biggest sources of buzz at FOSS4G was CartoDB. It is a hosted solution from Vizzuality that uses PostGIS to allow you to store your spatial data online. I got a beta account a couple of weeks ago but life (i.e. paying work) kept getting in the way but I finally got to play with it recently.

One of the things that intrigued me is that, similar to Google Fusion Tables, CartoDB exposes a SQL interface through a RESTful API (I’m still not sure if the term “API” applies to REST but it’s a convenient shorthand). Essentially, CartoDB exposes PostgreSQL SQL and the spatial SQL extensions of PostGIS. Once your data is loaded, you can query it and return the results as either CartoDB’s JSON syntax, KML or GeoJSON.

With this information, I set out to build a simple application to query property data and display the results on a map in a browser. In addition to CartoDB, I elected to use the Leaflet Javascript library to accomplish the mapping (although I also experimented with OpenLayers). Displaying and styling GeoJSON in Leaflet is very straightforward and this task gave me and excuse to get a little more comfortable with it.

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Mapping GISP and PMP Certifications with GeoCommons and the ESRI Silverlight API

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Note: The application described in this post is running here. It requires Silverlight 4.

I was perusing my LinkedIn connections and noticed that quite a few had PMP certifications. I also noticed that most of those who did seemed to be in the Washington, DC area. Of course, given that I live in that region, my sample could be a bit skewed but then I started thinking out loud (via Twitter):

I would love to see a heat map showing concentrations of PMPs. I bet the DC area would be white-hot. I suspect others not so much.

Naturally, I could not let this sit. How hard could it be? It turns out it wasn’t that hard so I decided to throw a small app together to look at the data. In the process of working out an approach, I decided to also look at GISP certifications because the data set is smaller and is available as one download from the GISCI. Here’s a blow-by-blow:

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Flashback…

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Just back from vacation 🙁 and as a way of easing back into things, I have been tinkering with my WCF project that’s been sitting while the paying work has gotten done. It’s the one that wraps PostGIS coordinate conversion as a web service written using WCF. My copy of “Professional WCF Programming” arrived while … Read more

Standalone IE6

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Okay, this really has nothing to do with GIS but I wanted to get this info out there. I have a particular piece of software that I use regularly that involves connecting a device to my PC to exchange information. This software does not work with IE7 yet. Since automatic updates doesn’t really give you … Read more