Category: Mapping

Hot Spot Analysis of 911 Calls map is available

By Charlie Frye, Esri Chief Cartographer

Link to Hot Spot map

The Hot Spot Analysis poster shows the steps in the analysis of 911 Call data. The data were processed using the Hot Spot Analysis tool and the design of the poster is, we think, faithful to the underlying data.

I did the first edition of this poster almost three years ago, and since then it has been tacked up on the wall at the end of one the hallways here in Redlands. When Jack brought his tours through the Software Products & Development area, he’d often show this poster, extolling the analytical power of GIS. The original poster was a little overly flashy, but more importantly after we recently checked with our spatial statistics experts, we found it was symbolized in a way that was slightly misleading. Thus, we undertook an upgrade and presented it at the Users Conference in our ”Mapping the Results of Your Geographic Analysis” technical session. Continue reading

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Clearly labeling overlapping polygons

By Charlie Frye, Esri Chief Cartographer

Three Overlapping Polygons with labels that clearly apply to a specific polygon

Not long ago a colleague wrote me saying she had overlapping polygons that need to be clearly labeled so she’d know to which polygon each label pertains. She sent me the drawing done in PowerPoint of the desired result but wanted it as an automated solution in ArcMap. Continue reading

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The Integrate tool

By Charlie Frye, Esri Chief Cartographer

Example showing the result of Polygon to Line tool where insufficient topology caused broken line segments to result.

I dropped a hint about the Integrate tool in the previous post and decided it was worth giving a bit more time to. The way I found out about the Integrate tool was through working on a different problem altogether – I was helping somebody who was trying to figure out why the Polygon to Line tool produced lines that were all broken up thus defeating his purpose of symbolizing boundary lines the way he wanted to. Continue reading

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Simplifying lines and polygons that intersect with other lines and polygons

By Charlie Frye, Esri Chief Cartographer

Example of hydrographic data compiled for 1:5,000 scale maps

There are quite a few tools in the ArcGIS toolbox that are designed to, and depending on your goal, work well for generalizing a single feature class. The downside to that is many feature classes of data can be required make a given map and all should be displayed at a level of detail that is appropriate for the map scale. Simplifying one feature class at a time will not account for intersections between two line feature classes, two polygon feature classes, or a line and a polygon feature class. What follows is a method that can be used to simplify the lines in two feature classes while preserving the location of any intersections. Essentially what you will do is to put all the features into one feature class, generalize that, and then split them out into the final feature classes. Continue reading

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Displaying a perimeter for all polygons in a dataset

By Charlie Frye, Esri Chief Cartographer

The goal is to show just the perimeter for all the polygons in the dataset

We were asked, not long ago:

“I’ve got a dataset with polygons that represent the extent of field study areas at different dates; these study areas have grown over time and I want to show a single polygon that represents each site’s current study area, while still allowing me to Identify anywhere within the area, be able to see other features inside of the study areas, and I cannot be saddled with a geoprocessing experience every time I need to make my status maps for any of the study areas; How can I do this?” Continue reading

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Esri_Optimized.style available in ArcGIS 9.2

By Charlie Frye, Esri Chief Cartographer

Quite a few people saw technical sessions in San Diego at the Users Conference where the Esri_Optimized.style was mentioned. A number of you have written in, asking, “What exactly is it?” and “Where can I find it?” Continue reading

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Choosing an appropriate cell size when interpolating raster data

By Charlie Frye, Esri Chief Cartographer

Choosing a raster cell size is a parameter in many tools

“If I want to create a digital elevation model (DEM) by interpolating from a point shapefile (digital terrain model or DTM), how can I select the most correct cell size given the original separation of the point file?” We recently received this question via the Ask a Cartographer Web page, so we checked with a couple of the product engineers on our Spatial Analyst development team and found that we didn’t have a help topic addressing the subject. Moreover, the answer was not simple—it varied depending upon why the DEM was needed. Continue reading

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Making maps that show flow from place to place

By Charlie Frye, Esri Chief Cartographer

Example of expressive flow arrow in a map made using ArcGIS

We’ve received a few requests this week asking how to use ArcMap to show flow from place to place. The requests ranged from, “What might the data look like?” to “How do I make the flow arrows?” One thing to note, this isn’t a topic that I have much first-hand experience with, but I can certainly get things started with the hopes that others will add their experiences and perhaps, together, we can build a body of knowledge to benefit us all. Continue reading

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Heads up color proofing for Esri style's colors

By Jenny Reiman, East-West Gateway Council of Governments

Layout from ColorPalette_ArcGIS.mxd

Here’s a useful little map document called ColorPalette_ArcGIS.mxd that I put together to anticipate the variation between colors on my monitor and the printers and plotters in the office. It contains no geographic data, only graphics that correspond to the standard color palette in ArcGIS. Each color swatch is labeled by name and by CMYK values. I print a copy from each printer and hang them near my monitor so I can choose colors for my layout based on what they look like on paper, not just based on what the colors look like on my monitor. Someday everything may be perfectly calibrated with a color matching system like Pantone. Until then, this helps – and it makes great cubicle wall paper!

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Finding depression contour lines

By Charlie Frye, Esri Chief Cartographer

Note the two depression contour lines with ticks pointing downhill

Unfortunately there currently is no automated way in ArcGIS to evaluate contour lines and select those that are depression contour lines. There are some tools in the Spatial Analyst extension such as FLOW DIRECTION, SINK and FILL which may look useful for this purpose, but in fact are designed to find small irregularities in digital elevation models (DEMs) and fix them, and thus they don’t find larger depressions, which are typically the basis for depression contour lines. Continue reading

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