Mapping Center

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...

We recently made some changes to the color ramp styles on Mapping Center under the ArcGIS Resources tab. You will now find a single ZIP file that contains a variety of color ramps. Our purpose in reorganizing the color ramps was to make it easier to find and use the color ramps.   The way we did that was to organize all the color ramps of a particular theme into a separate style file.  Then we gave each of the style file a name that better describes the purpose of the color ramps. Read More...

Hypsometric tinting (also called layer tinting, elevation tinting, elevation coloring or hypsometric coloring) is used to enhance elevation zones so map readers can better see differences in relief. You can think of it as "coloring between the lines" where the lines are contours (lines of equal elevation) or isobaths (lines of equal depth below the surface of a body of water). Hypsometric tints are often laid transparently over a hillshaded surface. Read More...

If you're making a map that is either a large format print map or a map that will be served via ArcGIS Server, squeezing every bit of wasted time out of drawing performance is critical. Don't get tired of sitting there drinking extra cups of coffee watching the word "Drawing", all your layer names, and that little blue globe. If you're finding it stressful to explain when updates will be coming, or the timing for caching the map you are serving, or your map services generate complaints about poor performance, then try the two tips in this entry. 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...

In the first dot density mapping blog, we discussed the workflow for creating dot density maps using ArcMap. In that discussion we emphasized the need for using exclusion or inclusion layers. Here is an example of how we set up the inclusion and exclusion choices for mapping population density in San Bernardino County, the county with the largest land area in the conterminous United States. Because of its size and the fact that population is not evenly distributed throughout the county (rather, it is concentrated in the southwest corner, around where Redlands is located), this county exemplifies the limitations of dot density mapping without inclusions/exclusions when mapping population density at the county, the state or even the country level. 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...

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...

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...

Keeping track of scale ranges at which a layer will be visible when a map has a few scale ranges and dozens of other layers can quickly become mind-boggling. This entry describes a strategy for using ArcMap's Table Of Contents (TOC) to create these maps and effectively manage all those layers and scales. Read More...

Quite some time ago we posted a blog entry on creating tint bands, which are bands of color either interior or exterior to polygons along their borders.  You will see this cartographic effect on world atlases, for example, using different colors to distinguish the various counties. The solution we presented was involved and complex, but it did preserve essential characteristics of the polygons better than any other method we tried. 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...

Using cartographic representations to make line symbols like those in the image to the right, where markers are displayed in conjunction with a dash pattern, requires more than just casual knowledge of the geometric effects. In fact, to make a line symbol like the one shown to the right, the default settings won't work. Read More...