Mapping Center

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...

I've often had the situation where I wanted to use a raster data source as a single-color map background layer, but the cell size or other data processing output resulted in a 'blocky' or 'pixelated' appearance to the data at the map scale I need.  A simple raster-to-vector data conversion served only to recreate the boxes or 'saw-tooth' or 'stair-step' lines from the original raster. The ArcScan extension has tools that reduce or remove this problem, and create an output vector data layer with smooth polygon boundaries or more naturally sinuous lines. 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...

Last week we received a good question on Ask a Cartographer: is there a way to create parcel hooks with ArcGIS 9.2? After first discovering what parcel hooks were and finding an example of a typical case (shown at left), the answer seemed like a ‘no-brainer'. Sure, just use the line decoration option on a marker line representation. However, after acquiring some parcel data that included parcel hooks (thanks to Greene County, NC) and seeing the circumstances where parcel hooks (they're also called land hooks or parcel ties) are placed on maps, I learned there are are several scenarios that need to be handled. Read More...