Mapping Center

September and October sure went fast. We on the Mapping Center team have been very busy working on mapping projects, and have not spent as much time here--but we're finding a balance and will be getting more good blogs out here soon (several are in the pipeline).

Now there is a new blog, the ArcGIS Data Blog, that you should subscribe to in order to keep up on what's new with all of ESRI's data--this will give you an advantage by being able to produce better maps because you've got better content to use Read More...

In the next couple of blog posts, we want to explain a bit about the two tools you can use to create buffers in ArcGIS. Buffers are used not only in analysis of distances and areas around point, line and area features, they are also used in mapping to achieve a number of cartographic effects, such as coastal vignettes. Since there are two tools and multiple methods you can use to create buffers, and each have their particular strengths and weaknesses, we thought it would be good to review these for you. In the next couple of blog posts, we'll describe the tools and methods, how they differ and what you need to consider when using them. Read More...

A couple of weeks ago, Aileen wrote a blog post called "About geographic transformations and how to choose the right one". In it, she described many of the parameters that you can set for map projections.  Two that were not mentioned were angular and linear units, so I thought it might help to describe them here. Read More...

Last week's blog post Filling in and clipping in a raster described how to fill in holes in a "bad DEM" using data from an existing "good DEM", then clip it to the outline of a feature.

The blog post suggested using some ArcGIS geoprocessing tools that available with the Spatial Analyst extension. As with most GIS operations, there is more than one way to get to the final answer! In this blog post, I describe how Map Algebra can be used to achieve the same results.

We can break this process down into three steps. Read More...

Sometimes you want to use raster data, like a digital elevation model (DEM), but it doesn't have the same exact extent as the area you are mapping. For example, if I use gtopo30 and "countries" data (available on the ESRI Data and Maps CD) to create map of the Pacific Northwest, the coastline boundaries do not coincide. In some places the elevation values are missing for inland areas, and in other places, there are elevation values outside the extent of the land area. So we need a way to clean up the data and make them coincide. Just clipping won't work as this won't add the missing elevation values.

I can fix all this if I have some other elevation data to fill in the missing interior elevation. For example, I can use etopo2 data (also on the Data and Maps CD) to get the elevation values for the pixels that need them. Read More...

This post, is to announce the release of a map template for historical GIS called Historical GIS:  Boston 1775. If you’ve never given historical GIS a second, or a first thought, you might find the contents interesting and maybe even applicable to your work. Consider that the vast majority of GIS data is historical, even if it’s only a few minutes old. Read More...

You will often be prompted to select the geographic transformation when you are projecting data or setting the projection of a data frame in a map document. Here are some concepts that might help you understand what this is all about AND how to make the right selection.

First, "geographic coordinates" are expressed in terms of latitude and longitude. "Latitude" is the north-south angular measure from the equator to the point of interest. "Longitude" is the east-west angular measure along the equator from the prime meridian to the point of interest's longitude. Assuming that the earth is a sphere, geographic coordinates are determined relative to the center of the sphere - these coordinates are called "geocentric latitude and longitude". (See the figure at the right; all figures are from Map Use: Reading and Analysis, 6th edition, ESRI Press.) Read More...

From time to time we've had to create some building footprint data. A colleague was in my office yesterday looking at the map to the right, and remarked that he thought that adding building footprints to maps "humanizes" the map. An interesting observation, and one that I'm not inclined to argue against.

We've learned a few tricks for making haste with little or no waste to produce building footprint data. Read More...

Sometimes you will find that some annotation you had thought you produced is missing. You can add this missing annotation into your existing annotation feature class without having to recreate all the annotation. The approach you take will depend on whether you are creating standard annotation or feature-linked annotation.

Standard annotation elements are pieces of geographically placed text that are not formally associated with features in the geodatabase. For example, you might have a piece of standard annotation that represents a mountain range—the annotation simply marks the general area on the map. Read More...

Recently, a group of us were annotating an online map that covers the contiguous United States at multiple scales. After a few weeks and many hours of annotation work, we came up with a list of tips that may be useful to you as well in your annotation editing. Read More...

As you zoom in (or out) of the online maps you see on Virtual Earth (VE) or Google Maps (GM), you are actually seeing a series of different maps with slightly different information displayed at each zoom level. Zoom level is indicated and controlled in an online map by the vertical zoom slider, like the one shown at the left in the image here. Whenever the zoom level is changed, a different map is shown.

Of course, these maps are well designed so that viewers are largely unaware that they are seeing these different maps. The foundation for good design of an “online map” hinges on understanding how to design for each of the zoom level represented in the entire online map. Colors, fonts, number of and types of features, etc. are all seriously considered when each of the maps is created for each of the zoom levels. Read More...

We’ve blogged about symbolizing hillshades (rasters that are derived from elevation raster datasets, like DEMs, via the Hillshade tool), but never really covered the basics of the data used to create hillshades, so we wanted to take a minute and share a few best practices we’ve been adopting.

Before getting started, though, it’s worth noting that we’ve been storing our rasters in file geodatabases. For us, these included some rather large hillshade datasets, ranging between 5Gb and 60Gb. Read More...

We’ve been compiling a list of "What I wish I had known about ModelBuilder before I started using it". Here are a few things that made the list:

1. Create personalized tools in ModelBuilder: Until a few days ago, I thought Read More...

Buffer vignettes symbolize the interface between two areas. They are often used to show the land-water interface by gradually fading blue at the coast into white or vice versa. You can also use them to fade the map out into a white background. These types of vignettes are created using buffers that are symbolized in a special way.

Note -- as described this only works on white backgrounds. See the two examples at the end to see how the data frame's background can be coordinated with the buffer vignette for different effects on along coastlines. Read More...