Category: Mapping

Displaying coincident points

By Charlie Frye, Esri Chief Cartographer

We’ve had a number of folks writing in on Ask a Cartographer wondering how to displace or offset coincident points so all the points could be seen. Data with coincident points is most commonly produced as a result of geocoding addresses. There are at least two ways to handle displaying this data.  One would be to create a graduated or proportional symbol thematic map, and to do that the input point data would be processed with the Collect Events tool, which would produce output containing points that represented the locations and an attribute that indicated how many points were at that location. Continue reading

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Gulf of St. Lawrence locator map is available

By Charlie Frye, Esri Chief Cartographer

The Gulf of St. Lawrence map was originally created for an Esri tutorial on how to publish a map to ArcReader.  The intent was to include a simple locator map with a few basic functions.  These cartographic effects and tasks are highlighted:

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By Charlie Frye, Esri Chief Cartographer

At the Esri User Conference this year we showed, in our technical session on lessons learned in cartographic data modeling, a tool we’ve been using for a few years now.  It’s called ScaleMaster, and we initially developed it to examine the idea that different kinds of geographic data (roads, lakes, rivers, contour lines, etc.) have differing levels of sensitivity to map scale change.  The “we”, in this case, was a collaboration between Dr. Cindy Brewer of The Pennsylvania State University, Dr. Barbara “babs” Buttenfield of the University of Colorado at Boulder, and ESRI.  ScaleMaster worked well to confirm our suspicions, and we also saw some additional utility in expanding ScaleMaster a bit. Continue reading

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Organizing layers with too many unique values

By Charlie Frye, Esri Chief Cartographer

If you make zoning, soils, geology, or any of a number of kinds of maps where your data represent many different types of features, you can make use of some specialized functionality in the unique values symbology method in ArcMap’s layer properties symbology tab.  This functionality allows you to create headings within your layer’s symbols that will be shown in ArcMap’s table of contents and in your map’s legend.  Continue reading

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We’re back from the International Cartographic Conference in Moscow, Russia

By Charlie Frye, Esri Chief Cartographer

For those of you who may not have heard of the ICC, it is the meeting of the International Cartographic Association (ICA). The ICC happens every two years, moving from continent to continent — for example the 2009 meeting will be in Santiago, Chile. Representatives from national mapping organizations, university cartography programs, and of course venders and solutions providers from around the world come to the ICC to share the latest research in many areas of cartography. The conference sessions are based on and organized by commissions which are groups of people who work on specific areas of cartography, like generalization, mountain cartography, or Internet maps. Each commission has a research agenda and its members present papers and have commission meetings at the ICC. Many commissions also opt to have meetings in the years between the ICC meetings. The <a title=”ICA homepage” href=”” ICA website has a <a title=”link to list of ICA commissions” href=”” complete listing of all the commissions; if you’re interested in participating, please email the commission chairperson. Continue reading

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Verbal scales

By Aileen Buckley, Mapping Center Lead

Verbal Scales - Thumbnail

A verbal scale is also referred to as a “word statement” or a “scale expression”, and in the ArcGIS software, it is one of the options for inserting “scale text”. It is offered in the form of a relationship between map distance and ground distance stated in standard units that we understand for both sides of the relation. For example, if we say that a map that is “one inch to the mile”, we understand (at least in the U.S.) the units on both sides of the relation. This is the same as a map that is 1:63,360, but for many map makers and map users, we will often translate this mentally into “one inch to the mile” because we can intuit that more easily (figure 1). Continue reading

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Representative fractions

By Aileen Buckley, Mapping Center Lead

A representative fraction (RF) is the ratio of distance on the map to distance on the ground. Representative fractions are expressed in the form of 1 followed by a : (colon) and then a number, where the one is the numerator in the fraction, the colon represents the division operation, and the other number is the denominator. Thus, a scale of 1:24,000 can be expressed mathematically as 1/24,000. In fact, on some maps, you will see the RF represented using a division sign. Continue reading

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Choosing the best way to indicate map scale

By Aileen Buckley, Mapping Center Lead

In a previous blog entry, I asked, “Do all maps need a scale bar and north arrow?” I answered, “No” and talked a little about direction indicators like north arrows, but I didn’t really go into any detail about scale bars. Here is a bit more on map scale indicators, like scale bars. Continue reading

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Is there a way to make North Arrows look better?

Question: Is there a way to make North Arrows look better? I know you can change the overall color of a
North Arrow from say the standard Black to Red…but what about changing the individual elements? I have attached a picture I took of a North Arrow that I recently saw on a wall and wondered if it was something I could reproduce in ArcMap. (see attached pic)

Attachment: Picture of North Arrow

Answer: For the standard north arrows, which are based on font glyphs, what you see is pretty much what you get. However, a good deal more is possible. North arrows are based on Marker symbols, which can be created using an enhanced metafile (EMF) to supply the artwork. These files can be created using ArcMap or most standard illustration software packages (Adobe, Corel, etc.). So, literally anything you can draw can be used as a north arrow.

To use ArcMap to create the EMF file, I first resize my layout page to be a square, and then move the empty default data frame off to the side. Then I draw whatever I need, and finally export (File menu) the drawing to EMF.

Use the Style Manager to create a new marker symbol by selecting the Mark Symbol folder on the left and then right-click on the right, choosing “New”. In this case you’ll be making a Picture Marker symbol, and you’ll browse to and use the EMF file.

To make the North Arrow, continue working in the Style Manager, but select the North Arrows folder on the left, and create a new north arrow. In the lower right of the North Arrow properties dialog, click the Symbol button and add the picture marker symbol.

So, it may involve a bit more time to create such a custom north arrow, but it’s definitely possible.

Formerly a Mapping Center Ask a Cartographer  Q & A.

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Symbolizing the results of a Hot Spot analysis

By Charlie Frye, Esri Chief Cartographer

Example results of hot Spot Analysis tool

There are a number of spatial statistical analysis tools now available in ArcGIS. Some, like the Hot Spot Analysis tool produce specially structured results that can be misinterpreted or misrepresented if you approach symbolizing them in a generic way, such as using the Natural Breaks classification method. Specifically, the Hot Spot Analysis tool produces results that are in the form of Gi* Z Scores — values that indicate whether a feature is within a statistically significant hot or cold spot. While the version of this tool called Hot Spot Analysis with Rendering produces a layer that is symbolized correctly given the data it represents, you can fine tune this symbology if you know what how to avoid inadvertently misrepresenting the analysis results. If you’re working with point features, you can interpolate a raster surface from those points; you will also need to know how to symbolize the hot spot analysis raster surface properly. Here are some tips to guide you. Continue reading

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