Mapping Center

The style files that are installed with ArcMap are actually Microsoft Access databases, the file extension was changed from .mdb to .style.  Based on this knowledge, we'll describe a few useful things you can do to edit your style files using Microsoft Access. These tasks are either not possible or a bit tedious to accomplish easily in ArcMap. Read More...

If you want to remove selected features from display with standard ArcMap symbol management tools, you need to use the Layer Properties to do so.  Typically this might mean using a Definition Query based on a feature attribute value, or a classification scheme which excludes a range of attribute values.  Cartographic representations provide you with a method for removing features from display, this method is based on graphic selection.

You could use this functionality in the case where you want to create a map for a time or scenario that is not reflected in your current data.  For example, the Crater Lake National Park data which we use in Mapping Center is recently captured National Park Service data.  If I want to re-create a Crater Lake National Park map from the 1950s Read More...

Not long ago we received a question via Ask a Cartographer that our map projection experts frequently get; it goes something like this:  "When projecting data to WGS84, for example, which transformation is the best to use?"

There are two contexts for this scenario in ArcGIS. The first is as described above, namely, you need to project data and are potentially confronted by a lot of transformation methods and don't know which to choose.  The second context is a bit more complex, which is that you've added data from several sources to your map and you get a somewhat verbose warning (shown at right) that is, if you are like us, all too easy too ignore since it looks complicated. Read More...

Those of you who regularly use the classification dialog will have noticed a new classification method was added in version 9.2. Now available for all data is the geometrical interval classification method which was called "smart quantiles" when it was originally introduced in the ESRI Geostatistical Analyst extension.

This classification method was used for visualizing continuous data and to provide an alternative to the Natural Breaks (Jenks), quantiles, and really any variance minimized (within classes) classification method. The specific benefit of the geometrical intervals classification is Read More...

A number of you have written in to Ask a Cartographer wishing to know how to convert your font-based or EMF-based marker symbols to representation markers.  Representation markers (introduced in ArcGIS 9.2) have a number of advantages over font- or graphics-based markers.  For example, you can create or edit their artwork while working in ArcMap or ArcCatalog, and they can be used the geoprocessing framework.  One geoprocessing tool engineered to work with cartographic representations which you might find particularly useful is the Detect Graphic Conflict tool, which tells you where the symbols on your map overlap one another.  But first, many of you may need to convert a significant number of markers into representation markers. Read More...

In the United States, the Public Land Survey System (PLSS) is a way of subdividing land. The USGS topographic map symbols for displaying PLSS data are an excellent way to symbolize PLSS data on not only topographic maps, but because the topographic symbols are  so well recognized, the same symbols can be used on many other kinds of maps. In the image to the left, the "plus" marker symbol shows where a found corner is located, however, if no corner has been found, then no marker should be shown, leaving a gap that signifies the doubtful location of the corner. Next we will describe how to use cartographic representations to symbolize township, range, or section lines to leave a gap at the corners, allowing corners to be added (as point features) or gaps to be shown. Read More...

Exporting to an external graphics package like Adobe Illustrator or Macromedia Freehand from the ArcMap environment can have its challenges. One positive aspect of exporting is the ability to make certain that CMYK values are retained for proper print color reproduction. Some of the challenges you may face after export are inconsistent vector line widths, irregular polygon shapes, and something our programmers call polygon dicing. Read More...