Mapping Center

One of the most frequently recurring topics on Mapping Center is what to do with stacks or clusters of point features on maps. In August 2007, I wrote a blog posting on how to use Maplex to display coincident points, and this worked for some scenarios, but not all. Read More...

We got a good question on Ask a Cartographer this morning.  The gist of the question was how to go about symbolizing street centerlines so they could be drawn using line symbol widths that reflected, at scale, the actual width of the road (as shown in the image to the left). This is a good cartographic solution because varying the line width adds hierarchy to the roads -otherwise it would be hard for you map reader to know which are wider or more heavily used. Read More...

Not too long ago we received a question on Ask a Cartographer about symbolizing polygons with a scalloped edge (like the old ArcInfo hardwire line symbol). Hoping to do better (scallop lines were a nice idea, but they didn't always turn out as good as I would have liked, so I rarely used them), I started experimenting with the options in representation symbology. I'm happy to report that there is a better solution. Read More...

After seeing my poster that described using dot maps to show soils at the AAG conference in Boston a few weeks ago, Charlie Frye suggested that I write this entry to describe my maps and the technique used to create them.  This seemed especially appropriate given the recent entries in this blog about dot maps. Read More...

Last week we received an interesting question on Ask a Cartographer about how to create tapered stream or river line symbols. Tapered symbols are actually a bit more complicated than what is shown to the left; those lines are proportionally scaled symbols that are based on an attribute value. Notice that each stream is a single line width.  Tapered symbols would actually change widths along the length of a given feature, giving a very smooth effect. Tapering is more useful for depicting flows that range widely in value or magnitude, whereas proportional symbols are usually an excellent solution for symbolizing rivers and streams. Read More...

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...

Text and imagery have had an uneasy relationship since the day they met.  Satellite imagery and aerial photographs are the ultimate variable background, which makes any text drawn on them hard to read. Read More...

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...

The map excerpt shown at right (click on it to see the details) shows an example of hollow cased roads.  The map is from a mosaic of USGS DRG image files.  The map specification requires that the cased road symbol contains a transparent gap.  The examples shown below were created with ArcMap 9.2 and used cartographic representations to re-create the effect on the USGS DRG map. Read More...

The illustration at left shows a map the Paris Metro system (RATP).  The routes are depicted in a schematic view and this kind of map is challenging to create because multiple routes may share the same path, for example multiple bus routes along a single road or track. When this happens, the coincident routes are offset in a fashion that makes it possible to understand the path each route is taking. When using ArcMap and line features for the routes, the coincident features draw on top of one another, making it difficult to visualize. Read More...

Symbolizing road overpasses or underpasses typically requires that you perform two data preparation steps.  First, identify which roads overpass other roads.  This may be very simple intersections between two roads, or it may include many other roads when dealing with complex highway interchanges.  Second, represent the interchanges clearly.  This task may mean simply changing feature or layer drawing order, or it can also mean knocking out or masking portions of underpassing features.  The image to the left shows the underpassing highway being masked by an overpassing street and railroad. Read More...

This is the first of three parts that cover how to symbolize roads with cased line symbols.  This first part will cover how to symbolize road centerline data so that the symbols look good, the second part will cover data modeling and symbolizing underpass/overpass relationships, and the third part will deal with symbolizing cul-de-sacs versus dead-end streets.  The primary inspiration for this task is the design of the USGS 1:24,000-scale topographic quadrangle maps. To the left is an example from the 1952 Manchester, New Hampshire map. Read More...

We received a suggestion to write a blog entry on this topic from Anna Schwabedal, who is a technical sales representative for ESRI Germany.  Anna gave us a rough idea of how this works and I was able to use that when this topic came up through Ask a Cartographer recently, and I've worked on it a bit more since in order to write this. Read More...

A number of maps, particularly those geared towards outdoor tourism, rely on a convention that uses standard icons to list the services or amenities that are available at some place on the map. Using cartographic representations simplifies what used to be a rather unwieldy task from the perspectives of data modeling, data management, and symbology. Read More...

Dash-dot line symbols for polygon outlines should be displayed in a way that consistently shows the pattern of dashes and dots and clearly shows the shape of the polygon. In ArcGIS, a multi-layer line symbol is required. One layer is a cartographic line symbol with a dash pattern.  The second is a marker line symbol that shows a marker (the dot) with a complementary pattern to the dashes. Read More...