Mapping Center

Tree symbols are a great way to enhance the appearance of a large scale, detailed map. To make attractive point symbols for trees, you need a good place to start from and thankfully all of us ArcGIS users have that. Using multi-layer character marker sybmols, the variety of tree symbols you can create is endless. This blog is meant to introduce (or reintroduce) you to the ESRI US Forestry 2 font. It is also meant to give you some tips for creating a variety of tree symbols to use on your maps. Read More...

Need to add a quick locator map to your page layout? Want to spice things up a bit? Try this locator map – it has visual appeal because of the 3D appearance (promoted by the choice of projection and the gradient fill). There are just a few basic steps to creating this map: 1) Prepare the data to make the map, 2) create the map, 3) add your area of interest (optional), and 4) export the data used to make the map, if desired (this will save some drawing time for you.)

Note that this is a technique you would want to use only if your area of interest is large enough to be seen on the map, and it is best used when you want the map reader to get an idea of where in the world your area of interest is located. Read More...

We’ve posted our recently revised Color Ramps version 2.0 styles on our site to be more suitable for your use. Our impetus was we needed something new to work on a project with the topic of Washington Landforms and it is specific to printed maps. This is a map that we will talk about in our "One Minute Cartographer" session at the ESRI User Conference this year. This presentation will be posted on the Mapping Center - Other Resources page after the conference. The color ramp used on this map was selected from the PNW_x set in the new Hypsometry style. (PNW stands for "Pacific Northwest".) Read More...

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...

From time to time we are challenged by our users to try and re-create a cartographic effect that is seen on a map that you saw somewhere. In a recent Ask a Cartographer question we were asked how you could recreate the effect shown below in the excerpt from a histoical map.

In this blog entry, we describe how you can do that and we also recap some of the other methods we have used for symbolizing shorelines. We review methods that use both raster and vector data. Read More...

It is often useful to use a hillshade raster to show terrain to support other information in a map such as an analytical surface like population density, or a thematic overlay like soils. There is one significant problem with this; however, which is that the shading from the hillshade modifies the colors of the main information layer making them artificially dark or washed out. That makes map reading and applying what you learn from a legend a frustrating task. For example, the legend for the map on the left is shown at the right--it's hard to figure anything out with so many similar colors in the legend and the added effect of varied gray tones within each soil polygon on the map. (One way you can help your map readers is to 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...

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...

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...

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...

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...

  There are some general guidelines you can follow regarding size of symbols on a map.  The key is legibility - that is, ability to be seen AND recognized.  Legibility can be affected by: size of symbols and type, Contrasting colors and shapes, Familiarity, Perfect vision and perfect viewing conditions

In relation to size in particular, the ability of an object to been seen from a distance relates to what is called the visual angle – or “a size that subtends one minute of angle (1/60th of a degree) at the eye”.  This is the angle between the light rays from the two ends of the viewed object as they hit the eye, as shown in the figure below. It is usually measured in degrees. Read More...

Symbolizing a hillshade raster layer (the output of the Spatial or 3D Analyst's Hillshade tool) seems pretty straight forward, in fact the default symbology (black to white ramp) doesn't look too bad. In fact, if your hillshade layer is the only layer in your map, and if you don't mind not seeing some of the details that have been visually absorbed into the darker tones, the default symbology is okay. To be fair, the default symbology for hillshades is for far more than just terrain depictions, so it's good to know what might be helpful when depicting terrain with a hillshade. The image to the left is an example of a hillshade using the default color ramp. Read More...