Posts Tagged ‘box shaped world’

Shapefiles, Actionscript 3.0, and Google Maps (Box Shaped World)

Monday, June 8th, 2009

[Editor's note: Tutorial for using the vanrikom classes to read in shapefiles in Flash and Flex AS3 and display them on a Google Maps mashup.]

Republished from the Box Shaped World blog. 28 April 2009.

I’m working an Adobe AIR application and I wanted to be able to have the user select a shapefile, and then parse it to create a KML file.  I didn’t want to have the user be responsible for creating a KML file.  I thought I might try and crack the shapefile enigma since it is a well documented format, but that would have taken time and I suddenly realized I’m not actually a developer :).  Instead, I found this set of Actionscript Classes to parse a shapefile in Flash.  Unfortunately, I didn’t find a very good tutorial on how to work with the classes.  The example is a little confusing (at least for me) and also uses a far file.  I’d never heard of far compressed files.  So I took the classes and created my own parser.  I thought I would post a tutorial on how to use these shapefile classes in conjunction with AIR and the Google Maps API for flash.  This technique would work with flex as well, I just didn’t want to have to write the code to upload a file.  I presume a few things with this.  The shapefile you are using for this should already have a geographic projection (e.g. latitude and longitude Geographic NAD 83).  In order to use the Google Maps API with AIR, you need a URL with a key associated with it.  Below are two zipfiles available for download.  The testfile.zip is the shapefile I was using.  The vanrikom.zip is the downloaded actionscript classes from the Google Code repository.  I had trouble downloading the using an svn so I did it manually.  I’ll save you the time by making it available here…unless the original author asks me to remove them.  There are parts that I find confusing with the way the reader was set up.  For some reason polyline inherits from polygon.  Intuitively to me it should be the other way around…but like I said, I’m not a developer.

This was all done using FlashDevelop and the Flex SDK 3.  There are 4 custom classes in addition to the mxml file.  Each are shown here.

Continue reading at Box Shaped World . . .

Flow Mapping (Box Shaped World)

Tuesday, June 2nd, 2009

uk-interdependenceminard

[Editor's note: Flow maps have always ranked high on my radar but constructing them has always been tedious. This post and academic paper link detail how they can be automated with programatically, including edge routing (not directly from A to B, but with bends to not overlap other connections).]

Republished from Box Shaped World.

Getting a head start on a new project that is more cartographic. It will involve mapping migration/flows from Australia to the Northern Territory (probably smaller geographic units than states). I like making maps, and so I’m excited to do some cartography beyond standard ArcGIS layouts. There are different possibilities on how to map this. Initially, I think I will use something like this that creates a more trunk/branch flow map instead of the typical straight line between places (Tobler’s Flowmapper). The project lead doesn’t like this style too much, but thought the trunk/branch style might work. We might pursue other mapping techniques, which would be cool to try and apply different map techniques to this area…

Continue reading at Box Shaped World . . .

Republished from Stanford Graphics paper.

Cartographers have long used flow maps to show the movement of objects from one location to another, such as the number of people in a migration, the amount of goods being traded, or the number of packets in a network. The advantage of flow maps is that they reduce visual clutter by merging edges. Most flow maps are drawn by hand and there are few computer algorithms available. We present a method for generating flow maps using hierarchical clustering given a set of nodes, positions, and flow data between the nodes. Our techniques are inspired by graph layout algorithms that minimize edge crossings and distort node positions while maintaining their relative position to one another. We demonstrate our technique by producing flow maps for network traffic, census data, and trade data.

Continue reading past abstract, includes source code . . .