Mapping Center

Yesterday I got an email from a long time colleague showing me an online map and asking, “When will it be possible to do this map with ArcGIS”? The map is the interactive map of Washington DC at http://dc.everyblock.com. In particular my friend was looking at the crime map wondering how the proportional symbols showing crimes became disaggregated as he zoomed in, eventually showing individual crime sites. Read More...

Please note that we will be on vacation the next two weeks and may not be able to get to your question until the end of August. We're a small team and we really love helping you, but we need to take this break so we can come back energized for the rest of the year! If you need immediate help, please contact your ESRI account representative. Read More...

Last week in the User Conference, I did a demo for a few people.  To a person, they were delighted to see what was possible. If you've got ArcMap 9.3 and a few minutes, do the following Read More...

The ESRI Map Book has become an annual must-have collectors item for ESRI International User Conference attendees and GIS users alike. The twenty-third volume of the ESRI Map Book showcases the innovative and inspiring accomplishments of GIS users around the world. The true excitement of this book lies in the discovery of which maps have made it from the 2007 ESRI International User Conference Map Gallery into publication. More than 100 full-color maps are featured from distinct industry categories such as cartography, environmental management, government, natural resources, planning and engineering, tourism, transportation, and utilities. Read More...

One of the most frequently recurring topics on Mapping Center is what to do with stacks or clusters of point features on maps. In August 2007, I wrote a blog posting on how to use Maplex to display coincident points, and this worked for some scenarios, but not all. Read More...

Not all of the new functionality for mapping and cartography was shown in the mapping section of the What's New in 9.3 PDF that's available on the new Resource Center. New with both the 3D and Spatial Analyst Extensions in ArcGIS 9.3 is the Contour with Barriers tool, which generates contours from a raster surface and allows you to limit the creation of the contours to either side of a barrier. This tool has several improvements over the the existing contour tool. Read More...

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...

I've spent the last few months immersing myself in ArcGIS 9.3, particularly ArcGIS Server and ArcGlobe in order to create some map and globe services and see how they work in ArcGIS clients, Google Earth, and Virtual Earth. These services need to look good and draw fast. One factor that can dramatically influence drawing performance is whether projection-on-the-fly is being used.  Projection-on-the-fly will slow your map down, anywhere from 30% to 1000% slower (depending on the coordinate systems involved). Read More...

Whether you’re labeling soils, buildings, geologic units, lakes, or parks; you’ll eventually be faced with the problem of the text for the label being larger than the polygon you’re labeling. In most cases we recommend offsetting the labels from the small polygons and using leader lines to positively associate the label with its feature. The general idea is to split up the labeling of a layer into at least two label classes, one for the normal case, and one for the small features. Read More...

ArcGIS 9.3 has hit the streets, meaning some of you should have it in hand this week, and most of you will have it in the coming weeks. After you get it installed definitely read the What's new in ArcGIS 9.3 PDF [13Mb] (it also installed with ArcGIS 9.3 at C:\Program Files\ArcGIS\Documentation\Whats_New_In_ArcGIS_93.PDF). Use the text search (CTRL-F) to find content, like "Maplex" or "Representations", or whatever term best describes the enhancement you've been hoping for. Read More...

Not long ago we found a workflow that demonstrated how convenient it would be to be able to copy a representation class. The situation arose as we were creating a map service for a map that had been designed for print. The problem was that many of the symbols were too small and detailed to be seen clearly on screen. Our symbols were already cartographic representations, so we didn't want to edit them (to make them larger) because we still needed them to produce our print map. We also didn't want to have to create and manage an extra copy of our data just to manage one additional attribute (the one added for representations). Read More...

Put yourself in the shoes of one of my interns, who was asked to use representations to replicate a 1:100,000 scale geologic map.  In less than two weeks she got it done, and did so well that the next thing I asked her to do was to test ArcGIS Server and make a map service with her map. Those intricate little point symbols on geologic maps that are rotated by their strike angles and labeled with their dip angles were just too small to be seen clearly on screen.  We needed to make them bigger. Read More...

We got one of those perennial 'tough nut' questions on Ask a Cartographer today. The question had to do with annotation versus Maplex and what are often called overflow labels, which I have also heard called "key lists". While we are able to recommend tips and tools for specific circumstances or implementations, the person asking was more interested in what is the best strategy and why. So here's their question:

"We produce a 1"=1000' City map book from our GIS, similar to the Thomas Bros. street guides. Read More...

Last month I was lucky enough to be invited to the USGS's Digital Mapping Techniques (DMT) conference. Unless you do geologic mapping this conference is likely not on your radar, but suffice to say it worth the effort to get to Moscow, Idaho on many counts.  One is that I met Andrew Wunderlich, who gave a great and detailed presentation on how he has been migrating a base of Adobe Illustrator files to ArcGIS. Read More...

The vertical change in the elevation of the land surface, when determined over a given horizontal distance-along a road or stream, for instance-is known as its slope (Figure 1). There are three primary ways to quantitatively express the slope between two points. In each, the lower the slope value, the flatter the terrain, and the higher the slope value, the steeper the terrain. The slope values may be expressed as a ratio, as a percentage or as an angle. Read More...