Monthly Archives: April 2011

Creating parapets for line-over-polygons

By Ken Field, Esri Research Cartographer

Parapet - thumbnail

We received an interesting question on Ask a Cartographer recently which asked if there is a way to create overpasses when the underlying objects are polygons rather than lines. For those familiar with Cartographic Representations, the use of the Create Overpass tool is a great way of creating masks and parapets when one line feature crosses another, for instance where a road crosses a river or when one road class crosses another. In these situations, the use of a parapet is helpful to ensure that the map reader doesn’t infer there to be an intersection rather than an over- or underpass. Figure 1 shows how the tool works successfully for linear features. Applying good cartographic design in this way ensures the map reader can easily decipher that the vertical red line feature crosses over the underlying line features.

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Storytelling with Maps Contest

Participate in the Storytelling with Maps contest and share your most interesting and engaging web map or mobile app for a chance to win a great prize. Entries will be judged on the effectiveness of making the subject matter interesting and understandable and engaging. The contest starts April 29 and ends June 10. Winners will be announced in July at the 2011 Esri International User Conference in San Diego. Learn more.

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Creating 3D cross sections for use in ArcGIS Explorer

After a recent post we received quite a few inquiries as to how cross sections are created for visualization in ArcGIS Explorer desktop, and we’ll go through the steps here.

The screen capture above is displaying seismic and geologic profiles (along with wells and well traces) as cross sections in 3D space. In the steps below we will use a photo of Mount St. Helens from it’s May 18th, 1980, eruption and visualize it as a 3D cross section in ArcGIS Explorer as a layer package. The techniques are the same for subsurface and above the surface visualization. Below is a screenshot of what our end result will look like:

In short, what we want to do is use a raster file or photo (the cross-section we want to display) as a point symbol, and scale and rotate it as needed.

To start we need a point feature to use for the location of the image. You can use an existing point feature or create a new one. One easy way to do this is to create a point note for Mount St. Helens in ArcGIS Explorer and share it as a layer package. Just right click the note on your map, choose share, then save as a layer package.

Open the layer package in ArcGlobe. We want to use an image as point symbol. This image will represent the cross section (Mount St. Helens in this example, and the seismic and geologic sections in the earlier example). To use an image as a symbol for the point we need to specifiy and adjust several properties.

In the ArcGlobe table of contents right-click on the layer and choose properties. Click the Globe Display tab, and do the following:

  • Check “Scale 3D symbols with distance”
  • Uncheck “Rasterize feature layer”

Then click OK and dismiss the dialog. Even though there are more properties to set it is important to click OK when you have modified properties on a tab. ArcGlobe has properties that are only available in certain combinations. If you set properties on one tab and then switch to another tab, a property that you want to set may not be available until the properties from the previous tab are applied. Sometimes this is the case on the same tab. For example, on the Globe Display tab “Scale 3D symbols with distance” is disabled until “Rasterize feature layer” is unchecked and applied. So remember to Apply or OK your changes as you make them.

Next, on the Elevation tab specify “Floating without a surface” and click OK.

On the layer properties Symbology tab we will specify the type of symbol and the image (ultimately our cross-section) to display as the point symbol. Choose “Single symbol” and click the symbol button.

Next, click “Edit Symbol…”

And choose “3D Markersymbol”

Now browse to or copy/paste a URL to the image you want to use as the symbol. For this example I will use this photo from the USGS website:

Click Open and the image loads in for use as a point symbol.


From here, the values you set will depend on the image you have chosen and how it scales in real world space, and some experimentation is necessary.

Increase the Size (Z) of the symbol to 30. Also uncheck “Keep aspect ratio.” After doing this it is important that you do not modify the Size (Z) setting again. If you do, you will have to start over and reload the image. Also set the Width (X) and Depth (Y) to equal amounts. We will use 10,000 as our starting point, but will modify those to achieve the desired scaling for this particular photo. Click 1:1 to see the entire image in the 3D Preview as shown below:

Next click the 3D placement tab and uncheck Display Face Front and set the Rotation angles X value to 90, as shown below:


Click Apply and see what it looks like in your map.

It is pretty close to where we want it to be but still needs some adjustment. The image looks a little bit bigger than the 3D mountain, so let’s fix that first. (Note that the size of the symbol in the table of contents is controlled by the Size (Z) that we originally set before un-checking Keep Aspect Ratio.)

Back at the size settings, I’ll size it to 9000 and see how that looks.

The scale of the image looks a little better now. Next I will slide the image down so the rim of the volcano in the image matches the 3D terrain. To do this, use layer properties and the Elevation tab and set the Layer offset to a lower value. In this case I will use -800.


After that adjustment the volcano rims are lining up better. But the horizontal alignment still looks to be a bit off. To correct that I’ll adjust the X offset. Here I have set it higher than it need be to -90 so we can get a better Idea for what this property does:

With a little more experimentation we find that a value of -18 looks pretty good.


We’re satisfied with how things scale and align now, but one more thing we can do to make the image look better is turn off the layer lighting property.

We’re finished, and now ready to create a layer package that we can open in ArcGIS Explorer desktop.

The layer package created above can be found on ArcGIS Online and you can also view a couple of videos on the Esri Facebook site that show what the layer package looks like in use:

  • Video 1 - a 360-degree tour of the cross section.
  • Video 2 - this one shows how you can view the lower edge of the photo through the surface. To navigate below the surface make sure to check Surface Avoidance off under ArcGIS Explorer Options > Flight Characteristics.

(Submitted by Mark Bockenhauer, ArcGIS Explorer program manager and lead product engineer)

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Designing the Irish Surnames map

By Ken Field, Esri Research Cartographer

Geogenealogy - thumbnail

Back in 2009, I (and my co-author Dr. Linda Beale) created a map showing the historical and numeric importance of Irish surnames. It won a few awards and featured briefly in a previous Mapping Center blog entry to recognize St. Patrick’s Day in 2010. A paper I wrote about this map has recently been published in the Society of Cartographers Bulletin that details the design philosophy and construction of the map in ArcGIS. Rather than repeating a description of the mapping techniques I used here, the paper itself is available to download from the Publications page of Mapping Center (courtesy of Society of Cartographers). But here is a brief review of the map.

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Service Pack 2 Ready to Download

Service Pack 2 is ready and available to download on the Resource Center.
This Service Pack contains performance improvements, maintenance fixes,
translation updates and includes all updates delivered since ArcGIS

All ArcGIS Desktop and Engine users should install it.

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Updating a feature's shape by sketching with the Continue Feature tool

ArcGIS 10 Service Pack 2 includes the new Continue Feature tool. Continue Feature allows me to resume digitizing an existing feature so its shape can be updated by sketching. For example, I can use Continue Feature to extend a line or add a part to a multipart feature by updating a feature’s edit sketch. These workflows were not originally available in ArcGIS 10 and required installing an Esri code sample to perform. However, they have been reincorporated and are now built into the software with the introduction of the Continue Feature tool.

Once I install ArcGIS 10 SP2, I need to add the Continue Feature tool to a toolbar from the Customize dialog box since it is not on the ArcMap interface by default. I click the Customize menu > Customize Mode, drag Continue Feature from the Commands tab, and drop it onto a toolbar. I can put it on any toolbar I want, but I like to add it to the Edit Vertices toolbar. This toolbar appears automatically when I am editing the shapes of features with the Edit tool, which is when I will be using Continue Feature.

Extending a line by sketching
One of the most common workflows I can accomplish with Continue Feature is to extend a line by adding new segments from the last vertex at the end of the existing sketch. Previously, in ArcGIS 10, I either needed to use the Esri code sample or create a new line and merge it with the existing one. Now, I can easily do this with Continue Feature.
I have a roads layer that needs to be updated to include a newly built portion. To extend the line, I double-click it with the Edit tool and click Continue Feature. When I do this, I see that the sketch is reversed from the direction I need to extend it. Right now, the last vertex in the sketch (shown in red) is actually at the location that should be the start point of the line when extended. I can right-click directly over the sketch and click Flip to change the line’s direction so I can digitize in the proper direction.

Similar to creating a new feature, I have access to any available sketch construction methods on the Feature Construction mini toolbar. These segments only need to be straight, but I could create the line with curves or by tracing it from the shapes of other features. I also can use keyboard shortcuts or right-click to access a menu of commands to help place vertices in the sketch. I need to finish the sketch when I am done digitizing the additional segments. Any attributes from the original feature are maintained in the updated feature.

Adding a part to a multipart feature
Continue Feature allows me to add a part to an existing feature to create a multipart polygon, line, or point (multipoint) feature. A multipart feature contains more than one part on the map but references one row in the attribute table. I have a layer containing wildlife habitats that needs a new zone added to it. This habitat should be represented as a multipart feature since it contains polygons that are geographically separated but have the same ID and ecological characteristics. I can use Continue Feature to digitize the new part without having to create a new feature and merge it with the existing one.

As with extending lines, I use the Edit tool to double-click the habitat polygon and click Continue Feature. When I am creating polygons or adding points to a multipoint feature, I just begin digitizing the new part. To create multipart lines or add even more parts to the polygon, I can right-click, click Finish Part, then continue digitizing the parts. I can also hold down the SHIFT key and double-click the last vertex as a shortcut to finishing the part.

I can now sketch the shape of the new part using any available construction method or shortcut. In this case, the coordinates of the habitat corners were obtained from a GPS track, so I can use absolute x,y to enter the vertices. When I am done, I finish the sketch to update the feature’s shape and make it a multipart feature. The original habitat zone’s attribute values are preserved and associated with both parts of the feature.

For more information about the Continue Feature tool, see Extending a line by sketching and Adding a part to a multipart feature in the ArcGIS Desktop Help.

Content provided by Rhonda from the Editing Team

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ArcGIS 10 (Desktop, Engine, Server) Service Pack 2 Ready

Service Pack 2 is ready and available to download on the Resource Center. This Service Pack contains performance improvements, maintenance fixes, translation updates and includes all updates delivered since ArcGIS 10.0.

Go get it and download it today.

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ACS Data is available in Business Analyst

 By Lucy Guerra

Esri just released two new American Community Survey (ACS) reports, the ACS Population Summary and ACS Housing Summary on Business Analyst Online.  Business Analyst Desktop users have immediate access to these reports. No downloads, no installation, the reports are already there!

To start using the new ACS reports, in Business Analyst Preferences, make sure that your BAO credentials are applied and that the checkboxes for online access are checked on in BA Preferences.

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Dev Meet Up – Denver, CO

Driving up to Denver Water in preparation for the Denver Dev Meet Up, I thought to myself, “How is anyone going to find this place?” Surprisingly, there were people there ready to join us within 15 minutes of us arriving. The ‘us’ to whom I refer would be Andy Gup and I. As part of the EDN Team, we have been traveling all over the U.S. conducting Dev Meet Ups in the hopes that we can get developers together to discuss geospatial technologies, complementary third-party tools, and development platforms that are supported by Esri. Bryan Franey from the Esri Regional Office in Denver came out to give us a helping hand. Denver holds a special place in our hearts, as this is a recurring location for the developers in nearby areas of Colorado.


For this particular Dev Meet Up that occurred on Tuesday, March 29th in Denver, we had an especially large group of developers that were very eager to share information about the projects they have been working on. No, really. When I say large group, I’m not kidding. We had so many lightning talks for this Dev Meet Up that we had to shorten the time on them just so we could get everyone in there. It was fun and somewhat challenging at the same time. Before we started the race with the lightning talks, Tom Tierney and Milton Ospina from NAVTEQ gave a well-received keynote speech that covered a bit of what NAVTEQ is involved in (yes, the car industry!) and about their public safety application samples.


And then we were off to the races!


Starting us off in one corner was Scott Mueller from Sanborn. Scott introduced his research on mixing ArcGIS Server with NoSQL databases. He is currently working on a blog page that covers his research. As for right now, the page is not up, but when it is, it will be at


In another corner we had Brandy Gavlin from ITTVIS. Her presentation on Post-Wildfire Erosion Remediation Tool using ENVI for ArcGIS really caught everyone’s attention. This presentation centered around combining image processing tools from ENVI with a Geoprocessing model in ArcGIS to model areas that were susceptible to erosion following a wildfire. The two main parameters in this model were the Normalized Burn Ratio (NBR) and terrain slope. The NBR is calculated using Landsat TM or ETM+ data from the near infrared and short wave infrared bands and a difference surface (dNBR) is created from pre and post fire images. Terrain data is then used to determine if a significant slope is present. If a moderate-high burn severity (dNBR > 0.44) is coincident with a slope greater than the set parameter, the area is flagged as high risk. The presentation concluded with a live demo of model builder running. Her Burn Severity Toolkit was particularly interesting, as it is known to extend ENVI’s capabilities.


In the next round, Kirk van Gorkom (@kvangork) from Forge Apps presented “Making Apps that Don’t Suck”, which really stresses the importance of being careful with user interface design. “Keep it simple” and “Take off your nerd hat” were two resonating messages that Kirk left with the audience. His full 36-minute presentation that he outstandingly performed at the 2011 Dev Summit back in March is available here on the ArcGIS Resource Center.


At the halfway point, Brian Timoney came up to promote using HTML5 to keep web maps simple. He demonstrated an HTML5 application that used mouse-over events to show basic demographic data using the Raphael.js JavaScript lib. View a similar demo to his example but with the inclusion of some charting features.


And then we turned to Allen Glen (@a_glen) from the City and County of Denver who covered embedding Java apps in a div tag by bootstrapping resources. This was a neat concept because it allows the developer to build apps that do not require much access to the host web page. He pointed out a few things like making sure to use a CSS reset so the style does not cascade into a div. I had a lot of requests for Allan Glenn’s “Building Distributed JavaScript Map Widgets” presentation which was really cool.


Rounding the corner to the finish line, Bryan Noyle (@bnoyle) from DTS Agile talked about Google and HTML5. He addressed the end of the Silverlight scare and the compatibility issues with Apple products. Soak in the boiled down version of the presentation as it was delivered at the 2011 Dev Summit.


At the finish line was Julie Kub from the Dept of Commerce in Broomfield, CO. She presented a system for queuing up multiple raster analysis process that can be spun up as cores become available. Because of the queue, the processing state is maintained after interruptions.


In between lightning talks, and of course at the end, everyone munched on the appetizers (was going to type apps, but was concerned people might get confused on what was being munched on) brought in by Jason’s Deli. Our raffle drawing for admission to the 2012 DevSummit went to George Engelbrecht. He said he went this year and enjoyed it, so we’ll get to see him again next year!


We had a very supportive crowd in Denver. They extended a wonderful welcome to us returning yet again for another Dev Meet Up. Thank you, Denver. Your gratuitous hospitality makes us feel all warm and fuzzy inside. We’ll be back!

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New World datasets are now available

Esri is pleased to offer all new World Countries and World Administrative Divisions datasets to all ArcGIS users. 

World Administrative Divisions 

Both datasets are based on source data provided by DeLorme Publishing Company, Inc., with additional attributes from Esri. These very detailed datasets of boundaries can be used at both large and small scales. They have been designed for use as a basemap that easily can be edited to fit a user’s needs and view of the political world.

World Countries

Each dataset includes attributes for name and ISO codes, along with continent information. Particularly useful are the Land_Type and Land_Rank fields which separate polygons based on their area size; these attributes can be used for rendering at different scales by providing the ability to turn off small islands which may clutter small scale views. The World Administrative Divisions dataset also includes notes describing disputed boundaries.

View the World Countries and World Administrative Divisions item details on to download the layer packages or visit the Esri Data & Maps World datasets page on the ArcGIS Content Resource Center for a list of all the world layers available for download on

Contributed by James Shimota

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