Indicatrix

The other day, I needed to draw a symmetrical object (a map point icon) in Inkscape, the wonderful free vector graphics editor. I was surprised to find that there is no symmetrical modeling feature, so I improvised. Here’s how to create a symmetrical polygon in…

This is a short post about how I migrated this blog from its previous home on WordPress to its new home here.

I first created a Jekyll theme I liked using Bootstrap. Then I imported the posts using a customized version of exitwp, which I modified to handle…

I’m working on a project where there is a long, scrolling page and I wanted to have a dialog that is draggable and resizeable that does not scroll away when the user scrolls down. As far as I could tell, there is no option to do this with jQuery UI’s dialog widget…

Analysis of accessibility is
generally undertaken in large regions, such as
metropolitan areas or
entire countries. Frequently
it also uses macro temporal scales, as in before-and-after
analysis. This analysis instead looks at micro scales, both spatial
and…

If you’re interested in Open Source GIS and especially QGIS, I highly suggest you give the blog “Under Dark” a read — the author seems to be very clued in the latest developments, and the blog is very active.

As you may have gathered, I like Git and GitHub. Today, I ran across a GitHub feature that is really cool and above and beyond the call of duty: not only do they produce and display diffs on text files, but also on image files! You can see an example in one of my repositories. Added points if you can figure out where the map tile is from!

I found this buried deep in an appendix of the Mapnik XML Schema Reference, and I thought it so useful I am reposting it here:

Zoom level Scale denominator

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Update 2012–02–02 17:57 -0800:I just wrote a post about another way to do this.

I really like QGIS. It’s a powerful GIS that runs on Linux (among other operating systems) and doesn’t require incredible amounts of CPU. One criticism I had of it was that it did not provide…