Mapping Center : Cartographic Concepts

The "Map Sandwich"

cfrye — Mon, 13 Jul 2009 20:44:00 GMT

Last week we started telling you about the new ArcGIS Online World Topographic Map. As I was working on the design of that map, with the intent of providing a better basis for mash-ups, I had an idea. It was born of frustration with the fact some mash-ups don't work because too much information obscures the base map, making for an unreadable, often ugly result. Demographic layers represent a great example of the kind of information that just doesn't always work well in a simple mash-up....(read more)

ColorBrewer Version 2.0

makella — Tue, 30 Jun 2009 22:00:00 GMT

Recently, a new version of ColorBrewer called ColorBrewer 2 (colorbrewer2.org) was released by Axis Maps (www.axismaps.com). ColorBrewer is a web tool for selecting colors for maps. The original ColorBrewer was released in 2002, and the update incorporates comments that the developers, Dr. Cynthia Brewer of Penn State University and Dr. Mark Harrower of University of Wisconsin Madison (he used to be a grad student at Penn State), have received over the years. Here are what some of the new features are....(read more)

Dot Density Mapping with ArcMap – Part 1

AlexQuintero — Thu, 24 Apr 2008 22:58:00 GMT

Several weeks ago, after a colloquium given by Dr. Aileen Buckley on the devolution of cartographic theory, we approached her about research opportunities that she mentioned. She was glad to accept our help and put us in contact with Dr. A. Jon Kimerling from the Oregon State University. The research he was undertaking during his sabbatical in Redlands, CA dealt with a particular mapping method in the cartographer's bag of tricks - dot density mapping. After discussing the research issues with Dr. Kimerling, we were tasked with developing a series of maps to supplement his research...(read more)

Dot maps vs. choropleth maps with random dot area symbols

kimerlia — Fri, 18 Apr 2008 00:25:00 GMT

Question: What is the difference between filling a polygon with randomly placed dots and creating a dot density map for the polygon?

Filling a polygon with a certain number of randomly placed dots is a form of choropleth mapping where random dots are the area symbol for a quantity that is assumed to be of uniform density throughout the polygon. The choropleth map seen below of San Bernardino county population density uses random dots in this manner....(read more)

Map Viewing Altitude

kimerlia — Mon, 25 Feb 2008 19:00:00 GMT

Have you ever wondered how you can figure out how far the viewing distance is from the center point of any map? For example, in my office I have a large map of the world on my wall. It has a scale of 1:9,000,000. How can you tell the viewing altitude for the map? This is a very good question that I was asked recently....(read more)

ESRI Press presents Designed Maps: A Sourcebook for GIS Users by Cynthia Brewer

mlaw — Wed, 20 Feb 2008 01:55:00 GMT

Cynthia Brewer’s new book titled Designed Maps: A Sourcebook for GIS Users is a companion piece designed to compliment the highly successful Designing Better Maps: A Guide for GIS Users published by ESRI Press in 2005. The goal of the book is to offer a graphics-intensive presentation of published maps, providing cartographic details that will prompt GIS users to think about their own maps and how to improve them....(read more)

Specifying mulitiple transformations for your data frame's coordinate system

cfrye — Tue, 23 Oct 2007 18:03:00 GMT

Not long ago we received a question via Ask a Cartographer that our map projection experts frequently get; it goes something like this: "When projecting data to WGS84, for example, which transformation is the best to use?"

There are two contexts for this scenario in ArcGIS. The first is as described above, namely, you need to project data and are potentially confronted by a lot of transformation methods and don't know which to choose. The second context is a bit more complex, which is that you've added data from several sources to your map and you get a somewhat verbose warning (shown at right) that is, if you are like us, all too easy too ignore since it looks complicated. ...(read more)

About the Geometrical Interval classification method

cfrye — Thu, 18 Oct 2007 22:10:00 GMT

Those of you who regularly use the classification dialog will have noticed a new classification method was added in version 9.2. Now available for all data is the geometrical interval classification method which was called "smart quantiles" when it was originally introduced in the ESRI Geostatistical Analyst extension.

This classification method was used for visualizing continuous data and to provide an alternative to the Natural Breaks (Jenks), quantiles, and really any variance minimized (within classes) classification method. The specific benefit of the geometrical intervals classification is...(read more)

Choosing an appropriate cell size when interpolating raster data

MappingCenterTeam — Tue, 03 Jul 2007 19:36:00 GMT

“If I want to create a digital elevation model (DEM) by interpolating from a point shapefile (digital terrain model or DTM), how can I select the most correct cell size given the original separation of the point file?” We recently received this question...(read more)