Mapping Center

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...

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...

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...

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...

I have recently "invented" a method for simplifying polygon map layers, which seems to give reasonable results. Probably many others have invented it before me, but I would like to present it in order to receive comments and advice on setting the appropriate parameters.

My task was to produce a national soil map suitable at 1:1,000,000 scale on the basis of a 1:200,000 map. The best method would probably be to have a geologist or soil scientist make a complete re-production for the new scale - but we needed a less expensive method. The challenge was to find a technique that would not totally erase soil types represented as many small polygons covering more than half of the area in some regions. Read More...

An aspect-slope map simultaneously shows the aspect (direction) and degree (steepness) of slope for a terrain (or other continuous surface).  Aspect categories are symbolized using hues (e.g., red, orange, yellow, etc.) and degree of slope classes are mapped with saturation (or brilliance of color) so that the steeper slopes are brighter.  This will result in a map that has the colors shown to the right. 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...

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...

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...

Which are the 30 or 500 most important of Minnesota’s famous 10,000 lakes?  Next, think about that question from the point of view of making a zoom-able map of the U.S. and how many lakes need to be shown as you zoom in.  That question boils down to how to decide which polygons to show.  Not all polygons are created equally, some are roughly round, some are banana shaped (like ox-bow lakes) some have lots of prongs (like a reservoir formed by U.S. Army Corps of Engineers dam), some are long and twisty like a pretzel. 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...

So, you have just spent a few minutes deep in concentration setting up your labeling rules and applied them.  ArcMap's little globe is spinning, spinning... spinning... and nothing.  Several of your labels didn't draw. Panic and go to MappingCenter. Right?

Not exactly. 

There are a few things we always do when diagnosing the "where's my label" scenarios, no matter what's being labeled or what labeling engine is being used.  Read More...

One issue we hear about from the folks who teach cartography with ArcGIS is that users who are new to ArcGIS have some frustration in learning how to make minor customizations to symbols in the style files that come with ArcGIS. For example, removing a layer from a multi-layer symbol, changing the color of part of a multi-layer symbol, or other minor edits that (in theory) ought to be easy to figure out how to do. Read More...

Complex maps such as topographic maps present several significant challenges for setting up labeling rules and creating annotation.  The first challenge is that these maps typically have many layers and types of features, requiring map authors to create and manage numerous label classes. Second, these layers may have a high density of features, which means that automated labeling for these maps requires loading all the data into the labeling engine and making your computer to work fairly hard. Third, some labels on the map are very important and should be placed optimally (e.g., labels for cities or very important landmarks); some labels can be placed with some flexibility (e.g., placing river or stream names along lines; there are many candidate positions along a given line); and some labels are just less important (e.g., labels for contours, which must yield to the other information on the map) Read More...