JournalismGIS http://www.journalismgis.com A resource for geographical storytelling Wed, 21 Dec 2011 23:01:40 +0000 en hourly 1 http://wordpress.org/?v=3.3 Using ArcMap and Census data to interpolate the population around a location http://www.journalismgis.com/2011/04/using-arcmap-and-census-data-to-interpolate-the-population-around-a-location/ http://www.journalismgis.com/2011/04/using-arcmap-and-census-data-to-interpolate-the-population-around-a-location/#comments Mon, 04 Apr 2011 22:43:40 +0000 Andrew Long http://www.journalismgis.com/?p=150

Shapefiles for the tutorial.

]]> http://www.journalismgis.com/2011/04/using-arcmap-and-census-data-to-interpolate-the-population-around-a-location/feed/ 2 Sliding map comparisons using jquery http://www.journalismgis.com/2011/03/sliding-maps-using-jquery/ http://www.journalismgis.com/2011/03/sliding-maps-using-jquery/#comments Fri, 18 Mar 2011 02:33:12 +0000 Andrew Long http://www.journalismgis.com/?p=147

If you’ve been following the Japanese earthquake you might have seen the “before and after” photo technique popularized by the New York Times. I always thought this technique would be a great way to compare choropleth maps. So, I was excited when I came across this jquery plugin that mimics the technique. Here is the map that I made out of some Maricopa County voting maps.


Larger map

The map is pretty easy to put together. First you need to produce your choropleth maps. You can do this with some open source GIS programs like QGIS and uDIG. I used ESRI’s ArcMap and exported two images as jpegs. The key here is that the images need to be the same size. Save one image as before.jpg and the other as after.jpg.


Make a folder that will contain your images, html and javascript.

Using a text editor make the html file. Here is the code:

<html>
<head>

#DECLARE JAVACRIPT
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.min.js"></script>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.7.1/jquery-ui.min.js"></script>
<script type="text/javascript" src="jquery.beforeafter.js"></script>

#DECLARE OPTIONS
<script type="text/javascript">
$(function(){
	$('#container').beforeAfter({
	animateIntro : true,
        introDelay : 500,
        introDuration : 500,
        showFullLinks : false
});
});
</script>
</head>

<body>

#MAKE IMAGE DIVS
<div id="container">
 <div><img alt="before" src="before.jpg" width="500" height="300" /></div>
 <div><img alt="after" src="after.jpg" width="500" height="600" /></div>
</div>

</body>
</html>

The first part of this code calls jquery and the plugin. Make sure you put the plugin javascript in your folder. The next sections defines the function. The plugin has some options that you can declare. In the body, we declare two divs. These will hold the images. To make the map bigger or smaller change these divs to match your image sizes. Once you have the html, javascript and images together, place the folder on a server. Here is a zip file of my folder.

EDIT: Apparently this plugin has a “No commercial” creative commons licence.

]]> http://www.journalismgis.com/2011/03/sliding-maps-using-jquery/feed/ 7 Spatial analysis on the cheap http://www.journalismgis.com/2011/03/spatial-analysis-on-the-cheap/ http://www.journalismgis.com/2011/03/spatial-analysis-on-the-cheap/#comments Thu, 10 Mar 2011 17:00:48 +0000 Andrew Long http://www.journalismgis.com/?p=142

This is the meat of a lightning talk I gave at the IRE CAR conference a couple of weeks ago called, “Beyond Mapping: Spatial Analysis on the Cheap.”  Download a PDF.

TEXTBOOK
Geospatial Analysis: A Comprehensive Guide to Principles, Techniques and Software Tools

SOFTWARE
OpenGeoDa
STARS (Space-Time Analysis of Regional Systems)
GeoViz Toolkit
SAGA (System for Automated Geoscientific Analysis)
PASSaGE (Pattern Analysis, Spatial Statistics and Geographic Exegesis)
CrimeStat III
Qgis with ftools, manageR

R
There is a Spatial Cran Task View that will load up all the R Spatial modules. These include:

Classes, reading, writing, handling spatial data
Point pattern analysis
Areal data analysisSpatial regression.

In R (case sensitive) type this code:

install.packages(“ctv”)
library(“ctv”)
install.views(“Spatial”)

Two useful packages are:

SpatStat

Maptools

PYTHON

PySal is a Python library for spatial analysis functions.

]]> http://www.journalismgis.com/2011/03/spatial-analysis-on-the-cheap/feed/ 1 Geospatial Revolution: Episode 3 http://www.journalismgis.com/2011/03/geospatial-revolution-episode-3/ http://www.journalismgis.com/2011/03/geospatial-revolution-episode-3/#comments Wed, 09 Mar 2011 20:40:02 +0000 Andrew Long http://www.journalismgis.com/?p=141

Episode 3 of the Penn State’s “Geospatial Revolution”

]]> http://www.journalismgis.com/2011/03/geospatial-revolution-episode-3/feed/ 0 New forum for journalists interested in discussing GIS http://www.journalismgis.com/2011/01/new-forum-for-journalists-interested-in-discussing-gis/ http://www.journalismgis.com/2011/01/new-forum-for-journalists-interested-in-discussing-gis/#comments Mon, 17 Jan 2011 22:14:56 +0000 Andrew Long http://www.journalismgis.com/?p=133

We’ve started a new forum for journalists interested in discussing GIS software, methods and data. The forum will obviously be a work in progress as we develop the appropriate categories for discussions. We hope to form a community to help promote geographical storytelling. I know the audience is small at the moment, but please take time to post a question or observation.

The forum is at: http://journalismGIS.com/forum

]]> http://www.journalismgis.com/2011/01/new-forum-for-journalists-interested-in-discussing-gis/feed/ 1 Our proposal for the Knight News Challenge moves on to round two http://www.journalismgis.com/2011/01/our-proposal-for-the-knight-news-challenge-moves-on-to-round-two/ http://www.journalismgis.com/2011/01/our-proposal-for-the-knight-news-challenge-moves-on-to-round-two/#comments Sun, 16 Jan 2011 13:29:51 +0000 Andrew Long http://www.journalismgis.com/?p=130

Last year we submitted a proposal to the fifth annual Knight News Challenge, a contest funding innovative ideas that help to transform community news. This year we learned that our proposal was selected to move on to the second round of the contest. The project will provide a rich set of free spatial analysis tools designed for journalists. The open source tools will be available to use for free online. We have until Jan. 31 to submit our expanded proposal. JournalismGIS.com will be the homebase of the project. If you have any tools that you would like to see developed or would like to help sponsor the project, please contact us.

]]> http://www.journalismgis.com/2011/01/our-proposal-for-the-knight-news-challenge-moves-on-to-round-two/feed/ 1 Google updates oblique imagery http://www.journalismgis.com/2011/01/google-updates-oblique-imagery/ http://www.journalismgis.com/2011/01/google-updates-oblique-imagery/#comments Sat, 15 Jan 2011 04:36:10 +0000 Andrew Long http://www.journalismgis.com/?p=125

Google Maps has updated the 45 degree or oblique imagery for a number of locations in the United States. Oblique images can provide a advantage over the traditional overhead view when presenting the area in informational graphics.

The cities that have been updated are:

Albuquerque, NM
Contra Costa County, CA
Escondido, CA
Long Beach, CA
Norfolk, VA
New Orleans, LA
San Antonio, TX
St Petersburg, FL
Tucson, AZ
Van Nuys, CA

The images are accessed by selecting 45 degree in the satellite map. Then zoom into the area like you normally would. The image will flip to the oblique view as you zoom in.

This is the Safeway in Tucson where the recent shootings took place. These were constructed in Photoshop with screen grabs.

Oblique

Larger version

Overhead

]]> http://www.journalismgis.com/2011/01/google-updates-oblique-imagery/feed/ 1 Making a choropleth map with Cartographer.js http://www.journalismgis.com/2010/11/making-a-choropleth-map-with-cartographer-js/ http://www.journalismgis.com/2010/11/making-a-choropleth-map-with-cartographer-js/#comments Thu, 25 Nov 2010 06:00:37 +0000 Andrew Long http://www.journalismgis.com/?p=124

Happy Thanksgiving! What am I thankful for? Besides my friends and family, I’m thankful for the Cartographer Javascript library. This library makes it easy to add choropleths, pie charts and point clusters into Google maps. The project is in the early stages, but looks promising. I especially love the ability to call color schemes from ColorBrewer. I’m excited to see developers actually take cartography into account when building mapping libraries.

Here is a quick tutorial to show how easy it is to make this interactive Google choropleth map. Download a zip of the project.

This project has 3 parts.

  1. A project folder.
  2. A folder for the javascript libraries, called “js.”
  3. HTML page.

How it works:

First we call the javascript libraries. The first call is for Google Maps. The examples are using V2…so you will need to grab an API code for this to work on your server. The next call is the Cartographer.js library and the third is the Raphael.js library. Cartographer uses the SVG engine from Raphael. 

<script type="text/javascript" src="http://maps.google.com/maps?file=api&v=2.x&key=GOOGLE-API-KEY-HERE"></script>
<script type="text/javascript" language="javascript" src="js/raphael-min.js"></script>
<script type="text/javascript" language="javascript" src="js/cartographer.min.0.4.js"></script>
<script language="javascript">

The next section is the javascript that makes the map work. Basically, Cartographer places pre-encoded polygons on the Google map. 

function load() {
  if( GBrowserIsCompatible() ) {
    var map = new GMap2(document.getElementById("map"));
    map.enableScrollWheelZoom();
    map.setCenter(new GLatLng(18, 0), 2);
    map.addControl(new GLargeMapControl());
    map.addControl(new GHierarchicalMapTypeControl());
    map.setMapType(G_PHYSICAL_MAP)
 
    var countyNames = (new String("APACHE,COCHISE,COCONINO,GILA,GRAHAM,GREENLEE,LA-PAZ,MARICOPA,MOHAVE,NAVAJO,PIMA,PINAL,SANTA-CRUZ,YAVAPAI,YUMA")).split(",");
	
	var percentBrewer=(new Array(34,62,43,62,65,48,67,55,73,54,47,58,32,65,57));
	
    var countyData = [];
    for( var i=0, ii=countyNames.length; i<ii; i++ ) { 
      var name = countyNames[i];
	  var value = percentBrewer[i];
	 var code = "AZ-" + name;
      countyData.push( { region:code, val:value, label: Cartographer.regions[code].name + " County, " + "AZ" } ); 	
    }
 
    var cartographer = Cartographer( map, { colorize:"#000", colorizeAlpha:.3 } );
    cartographer.choropleth(countyData, { colorScheme:"RdBu", reverseColors:"true"});
  }
}

The first part of this code creates the Google map.

Then we declare the variables. CountyNames is a alphabetical list of counties in Arizona. PercentBrewer is the percentage of votes Jan Brewer got in the mid-term election.

Next we loop the number of counties and place the counties and the values on the map.

Finally is the Cartographer declarations. ColorScheme can be customized or use a list of standard colors. This uses “RdBu” and then reverses it. The higher the number, the more Red the polygon will be. The lower the number the more Blue it will be. Read more about the choropleth declarations.

(To change counties: Create an alpha list of your counties. Put a dash “-” for any counties with spaces in them, like La-Paz. Change the “AZ-” to your two digit state code. For example CA for California. )

Now we build the map with some HTML.

<body onload="load()" onunload="GUnload()">
<h3>Percent of votes Brewer, 2010</h3>
<div id="map" style="width:500px; height:500px;"></div>
</body>

Here is the complete code. 

<html>
<head>
<script type="text/javascript" src="http://maps.google.com/maps?file=api&v=2.x&key=ADD-GOOGLE-API-KEY-HERE"></script>
<script type="text/javascript" language="javascript" src="js/raphael-min.js"></script>
<script type="text/javascript" language="javascript" src="js/cartographer.min.0.4.js"></script>
<script language="javascript"> 
 
function load() {
  if( GBrowserIsCompatible() ) {
    var map = new GMap2(document.getElementById("map"));
    map.enableScrollWheelZoom();
    map.setCenter(new GLatLng(18, 0), 2);
    map.addControl(new GLargeMapControl());
    map.addControl(new GHierarchicalMapTypeControl());
    map.setMapType(G_PHYSICAL_MAP)
 
    var countyNames = (new String("APACHE,COCHISE,COCONINO,GILA,GRAHAM,GREENLEE,LA-PAZ,MARICOPA,MOHAVE,NAVAJO,PIMA,PINAL,SANTA-CRUZ,YAVAPAI,YUMA")).split(",");
	
	var percentBrewer=(new Array(34,62,43,62,65,48,67,55,73,54,47,58,32,65,57));
	
    var countyData = [];
    for( var i=0, ii=countyNames.length; i<ii; i++ ) { 
      var name = countyNames[i];
	  var value = percentBrewer[i];
	 var code = "AZ-" + name;
      countyData.push( { region:code, val:value, label: Cartographer.regions[code].name + " County, " + "AZ" } ); 	
    }
 
    var cartographer = Cartographer( map, { colorize:"#000", colorizeAlpha:.3 } );
    cartographer.choropleth(countyData, { colorScheme:"RdBu", reverseColors:"true"});
  }
}
</script>
</head>
<body onload="load()" onunload="GUnload()">
<h3>Percent of votes Brewer, 2010</h3>
<div id="map" style="width:500px; height:500px;"></div>
</body>
</html>

Download a complete version of this project. Make sure you change the Google map API. More examples of choropleths using this method are available at the Cartographer website.

]]> http://www.journalismgis.com/2010/11/making-a-choropleth-map-with-cartographer-js/feed/ 11 Geospatial Revolution: Episode 2 http://www.journalismgis.com/2010/11/geospatial-revolution-episode-2/ http://www.journalismgis.com/2010/11/geospatial-revolution-episode-2/#comments Wed, 24 Nov 2010 17:00:39 +0000 Andrew Long http://www.journalismgis.com/?p=123

Episode 2 of the Penn State’s “Geospatial Revolution”

]]> http://www.journalismgis.com/2010/11/geospatial-revolution-episode-2/feed/ 0 Creating an Interactive Census Map http://www.journalismgis.com/2010/11/creating-an-interactive-census-map/ http://www.journalismgis.com/2010/11/creating-an-interactive-census-map/#comments Tue, 23 Nov 2010 15:37:32 +0000 Andrew Long http://www.journalismgis.com/?p=122

Len De Groot (@lendegroot) of the Knight Digital Media Center offers up this tutorial on how to make an interactive Census map using Geocommons.

“Creating an interactive census map is easy using the free GeoCommons map service. This video tutorial takes you through the process step-by-step. You will download map files from the U.S. Census Bureau Tiger Shapefile Library, download and edit population data from Bay Area Census and merge the two to make an interactive map that you can publish on your site.”

Geocommons Census Tutorial from kdmcinfo on Vimeo.

]]> http://www.journalismgis.com/2010/11/creating-an-interactive-census-map/feed/ 2