Understanding Geostatistical Analyst Layers

The Geostatistical Analyst (GA for short) uses sample points taken at
different locations in a landscape and creates (interpolates) a continuous surface.
The sample points are measurements of some phenomenon, such as radiation leaking
from a nuclear power plant, an oil spill, or elevation heights. Geostatistical
Analyst derives a surface using the values from the measured locations to predict
values for each location in the landscape. Continue reading

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ESRI Releases the ArcGIS API Evaluator

If you haven’t heard, the ArcGIS Development Team has just released a new .NET utility called the ESRI API Evaluator.  This handy tool allows you to scan all of your ArcGIS .NET code and generate a complete set of API usage statistics.  This will reveal the DLL dependencies, version information and the number of calls made to all ESRI assemblies, interfaces and members. 

Help improve the product
One of the most important features of this tool is that it allows you to send your API usage information directly to the ArcGIS Development Team.  Once received, this information will be used to:

1.    Better understand the APIs that our customers are using (most popular).
2.    Make improvements to focused areas of the SDK (documentation and samples).
3.    Make decisions for future API development projects.

API Evaluator Scenarios
Scenario I – Help improve the SDK
You have been working on a number of ArcGIS projects and have had difficulty implementing various parts of the SDK.  Use the API Evaluator to let ESRI know what areas of the API are most important to you by uploading the usage statistics without actually sending us the code!

Scenario II – Improve your code
You have been working on an agile development project with a team of developers.  You would like to discover which parts of the API have been used the most by the team and if code reuse has been maximized.  Use the API Evaluator to determine the number of calls to all interfaces, methods and properties in the .NET assemblies and look for areas of improvement.

Scenario III – Deployment
You would like to determine the .NET Framework version, and ArcGIS license and extension requirements for an application.  Use this information to help determine the software and licensing requirements for deployment systems.
It’s easy to use!

Step 1.  Start the tool and run a new scan.

Step 2.  Select the folder(s) you wish to scan.    
NOTE:  If you are scanning a Visual Studio 2005/2008 web application, build and publish the website to generate the precompiled assemblies first.


Step 3.  Optionally, supply your contact information if you plan to upload your scan to ESRI. 

Step 4 – Confirm your selections.


Step 5 – Review the results.

Step 6 – Upload results to ESRI. Simply select the “Upload Scan” menu.

A few reasons to give it a try
I’m sure you can think of many different uses for this tool, but in general, you can use this tool to: 

1.    Determine the general API usage for larger or unknown code samples.
2.    Determine the licensing required to run an application.
3.    Locate redundant code sections and make improvements.
4.    Detect library dependencies to help with deployment scenarios.
5.    Detect .NET version dependencies.
6.    And most importantly, help improve the product (see below).

More Information
Where can I download it?  You can download the tool from the ArcGIS Engine Code Gallery.
Where can I find more information? You can find the documentation on the ArcGIS Engine Resource Center online.

We want your feedback!

Although the “Upload Scan” functionality is 100% optional, we do appreciate all feedback from the developer community, so we hope you find this tool useful and you can spend a few minutes uploading the results back to ESRI. 

Let us know if you have any questions or feedback.

Thanks for your participation!
ArcGIS Development Team

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Glaciers, Glacier National Park, and Global Climate Change

Glacier National Park was named after the glaciers that carved and sculpted its landscape millions of years ago. But according to the Glacier National Park Web site by 2030 there will be no glaciers left in the park, the result of global climate change. The park originally had around 150 glaciers, but today there are 26.

Grinnell Glacier is one of those 26, and is a popular hiking destination. Here’s a recent photo, taken earlier this month during a stormy hike to the glacier’s edge. The photo shows Upper Grinnell Lake in the foreground, the edge of the Grinnell Glacier to its left, and the Salamander Glacier and Salamander Falls above the lake.

Photo by: Bern Szukalski

According to Wikipedia, Grinnell Glacier is one of the most photographed glaciers in the park. Photos dating back to the mid-1800s have been archived, providing documentation of the glacial retreat over the years (shown below from Wikipedia):

The USGS Northern Rocky Mountain Science Center has more details and photographs.

We can also take a look at Grinnell Glacier using ArcGIS Explorer. First we used the GeoNames Search task (covered in a previous post) to locate the glacier.


Here’s the glacier as seen in Explorer’s default map.

We can add the topo layer (from the layers tab on the ArcGIS Explorer Resource Center) for another perspective.

Comparing the imagery with the older topographic map using the transparency or swipe tools, we can see the change in the size of the lake and the glacier’s boundary.

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Some best practices for working with DEMs

By Charlie Frye, Esri Chief Cartographer

Most of us use digital elevation models (DEMs) which are raster data sets that represent a continuous elevation surface in which each cell represents the elevation at its location. DEM data are typically available in tiles that are sized to balance ease of data sharing with coverage so that those who need several tiles to cover their area of interest are not overburdened with extensive post-download data processing.

Continue reading

Posted in Mapping | Tagged , | 4 Comments

Updated ArcGIS Online Services for Hurricane Ike

Just a few days ago we published a blog post on the NOAA imagery services and ArcGIS Explorer maps available for download.

Those services are regularly being updated on ArcGIS Online, and whenever you open the map or layer (that you can download from the post above) you’ll see the latest published imagery.

Here’s what it looked like a few days ago:

And here’s what it looks like today:

Comparing the two you can see that a lot of new imagery has been added to the mosaic.

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Working with the Connect and Disconnect commands when editing a Geometric Network

The following post was contributed by Craig Gillgrass a product engineer on the geodatabase team who spends the lion’s share of his time working with geometric networks.

The topic of when to use the Connect and Disconnect commands when editing geometric network features came up a couple times during our Geometric Network session.  Based on those discussions and other questions from users I’ve re-written the help topic on these commands.  What follows is a variation of the new help topic which should be available online soon.

As covered in the topic About editing geometric network features; the geometric network automatically maintains connectivity between network features based on geometric coincidence. For example, when using the ArcMap snapping environment, if a junction is added along an edge, or one edge is added along another edge, they will automatically become connected to one another. The ArcMap snapping functionality will guarantee geometric coincidence when adding new network features amongst existing network features and ensure the proper connectivity is established. Therefore, it is generally not necessary to use the Connect and Disconnect commands with most network editing workflows, but there are some exceptions. 


The Connect command creates topological relationships between the selected feature and the features to which it is geometrically coincident; if features are not geometrically coincident with the selected feature, connectivity will not be established. Connect will also honor the subsumption rules of the geometric network; orphan junctions will be subsumed by user defined junctions when connectivity is established.

The following diagram demonstrates how Connect works in certain situations; the dashed arrow indicates on which feature Connect is being used. The legend can be used for both diagrams:



The Disconnect command removes the topological associations a feature has to other features in the network. Disconnect does not delete the selected feature from the database or geometric network.  It also does not remove the logical network information for the feature.

Disconnecting a connected junction will leave an orphan junction in its place. Disconnecting an edge honors the geometric network rule that an edge must always have junctions at its end points. Disconnecting an edge with user defined junctions at its end points will result in orphan junctions at the end points. Note that if orphan junctions are at the edge end points; new orphan junctions will not be created. Disconnecting an edge which has junctions that are only connected at mid-span along the edge will not result in the creation of an orphan junction.

The following diagram demonstrates how Disconnect works in certain situations; the dashed arrow indicates on which feature Disconnect is being used:

The Connect and Disconnect commands are designed to complement each other and should be used for transitory editing workflows which will be completed within a given edit session. You can think of them as bookends; used to start and end a workflow. Some examples of these kinds of workflows are:

  • Moving a feature without moving the features to which it is connected
  • Repositioning a junction or an edge along an existing edge
  • Inserting an edge feature between two existing network features.

The general workflow for these edits is to disconnect the feature, perform the edit, and connect the feature. Keep in mind that disconnecting a feature is designed to be a temporary situation. Since the geometric network determines connectivity based on geometric coincidence, disconnected features may become connected during editing, such as when a new feature is created coincident to a disconnected feature, or when performing a reconcile operation in which a feature is inserted coincident with the disconnected feature.

Other things to note about he Disconnect and Connect commands are:

  • Each works on the entire edge feature; not a section of the edge feature
  • It is not possible to Disconnect or Connect one end point of an edge, but not the other end point. Connect and Disconnect work on the entire feature.


The Connect and Disconnect commands can be used to improve your editing experience with network features; but using them does require an understanding of rules that govern geometric network editing; which is available in the About editing geometric network features topic . I’ve gone over some examples of when Connect and Disconnect can and should be used and what to be aware of when using these commands.

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Using 9.3 Web ADF controls in an ASP.NET Web Part and SharePoint 2007

My previous post about integrating 9.2 Web ADF controls in ASP.NET Web Parts discussed a number of workarounds required to successfully utilize ADF controls within a Web Part. For 9.3 the ArcGIS Server .NET development team took some time to evaluate and fix any issues encountered while using ADF controls in a custom user control, composite control or ASP.NET Web Part. We tested Web Part deployment within SharePoint 2007 and confirmed that it worked without any ADF specific workarounds. As a result, the 9.3 Web ADF provides a solid foundation for integrating GIS components in Web Parts designed for SharePoint deployment.

Click here to download a comprehensive Web ADF-Web Part sample (C# and VB.NET). The sample code includes two projects: a class library which contains Web Parts, and a Web application to assist in deployment and testing. The sample also includes a ReadMe.txt to get started and a Word document which steps through the SharePoint 2007 deployment process for ASP.NET AJAX-enabled Web Parts.

The class library project (ADFWebPart) contains two Web Parts: MapWebPart and MapGridViewWebPart. MapWebPart contains MapResourceManager, Map,Toolbar, and Toc controls. This sample illustrates how to add, structure, and initialize the aforementioned controls, add a custom tool, and expose properties for use in SharePoint.

MapGridViewWebPart contains a MapResourceManager and Map. It also contains an UpdatePanel with a GridView. It requires that a ScriptManager be in the page to enable asynchronous updates of the GridView (via the UpdatePanel).

This sample illustrates how to work with interactive graphics in the client via a map and table. A selection set is generated from a feature layer in an ArcGIS Server map service and managed as a Web-tier graphics layer. The graphics layer is rendered on the client using Web ADF JavaScript graphic features. Attributes of the selected set of features are displayed in the GridView. The visible fields and alias can be explicitly defined. Hovering over a row in the table will highlight the corresponding graphic feature in the map. Clicking on the row will zoom or pan to the feature.

All properties for setting the dynamic resource, data layer for display, feature limits and field aliases are public and presentable within SharePoint. An ArcGIS Online cached map service (StreetMap) is used as a background map resource to provide spatial context.

The following screenshot provides an example of both Web Parts deployed within SharePoint 2007.

 Web Parts in Share Point

To utilize either Web Part outside of SharePoint or to test before SharePoint deployment, use the file system Web application (CustomControlsWebSite) included with the sample. The Web application contains a simple aspx page designed to emulate a runtime scenario where an end user wants to add a Web Part within the current session. To personalize the page (e.g. add a Web Part at runtime) the current session must be associated with an authenticated user. By default, a file system Web site will use integrated authentication. If deploying as a Web application in IIS, you will need to disable anonymous access to the Web application in IIS. Enabling integrated authentication may offer the easiest solution since you do not need to configure or explicitly define authentication details; instead the authenticated user will be the user account under which the client (browser) is running.

The default personalization provider for ASP.NET 2.0 is SQL Express. If you do not have SQL Express installed, a personalization store will not be created (upon initial execution of the application) and an error will be returned when attempting to add the custom Web Part to the page at runtime. To alleviate this requirement, the Web site uses a custom personalization provider that stores information in text files. The code, markup, and discussion for this technique is provided in the Microsoft article Web Parts Personalization Providers.

Contributed by Rex Hansen of the ArcGIS Server .NET software development team

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Creating 3D Population Density Map

Question: I found a this great 3D population density map created by Time Magazine:

I have been trying to recreate this map look, but have had little luck.

Here are the steps I have been taking:
1. Using Transportation Analysis Zones with population data, I created the centroids of each zone.
2. Using Spatial Analyst, I used the kernal density tool to show population density of the centroids.
3. I overlayed the centroids on a TIN in ArcScene and extruded by the New raster created by the kernal density tool.

- Now I have “peaks” similar to the Time Magazine map, but it looks more like mountains then the clean spikes in their map.

Do I need to do some type of post processing or is there a better way of trying to recreate such a map?


Answer: On your first step, it looks to me like they just used City Points and then threw them into one of the Spatial Analyst’s interpolations tools; I’d start with IDW.  That will give you a surface that you’ll need in ArcScene or ArcGlobe.  It will be symbolized and used as it’s own base heights.

The only extrusion in this map is about a 5 mile extrusion on the states, and the states were also drawn on top as well.

A quick test in ArcScene showed me that I could use US States extruded to a height of 20,000 meters.  Then I displayed states as another layer, but this time I set the base height to 20,500 meters.  Then I would set the base height of the population surface to 20250, and on the Base Heights tab, it will obtain it’s elevation from a layer (itself).  You may have to adjust the population numbers (like add 20250 or normalize them if they’re spiking too high).

I’ll play around with this tonight and see what I come up with in terms of a more detailed set of steps and if I’m on track I’ll put it up on the Mapping Center blog as I’ve had a few people ask about making this sort of map lately, so it will be a good thing to publicize.  Thanks!

Formerly a Mapping Center Ask a Cartographer  Q & A.

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Tips and Tricks – Creating ArcSDE connection files on the fly using Python and ArcObjects

ArcGIS 9.3 does not provide a geoprocessing tool for creating ArcSDE
connection files (.sde files). Some of you have requested such a tool for security
reasons – typically because you do not want .sde connection files hanging
around on machines. Rather, you want to automatically create a connection file
in a temporary location, use it in your script or model, and then delete it
within the process you are running. Others need the ability to create .sde files
on the fly because the connection properties, such as what version to connect to,
are not known at the start of the process. Having to stop the process for someone
to manually create the .sde file with the correct properties really isn’t an
option anyone wants to entertain. Continue reading

Posted in Analysis & Geoprocessing | Tagged , | 3 Comments

Using The GeoNames Search Task

Find Place is one of the default tasks that you see when you first start Explorer. It’s a handy way to locate cities, towns, airports, zipcodes, and the like. But what about other places, like place names on a topo map? That’s where the GeoNames Search task can be used to complement Find Place, and leverage the vast GeoNames.org database.

Here’s a video showing how you can use GeoNames Search:


Now let’s take a closer look. We’ve been given directions to go to West Glacier, Montana, and then drive to a place called The Loop where we can find the trailhead to go to Swiftcurrent Pass, our final destination. We’ve added the topo layer from the resource center already, and that’s where we begin.

Using Find Place, we locate West Glacier, Montana.

To locate The Loop and Swiftcurrent Pass, both placenames on the topo map, we open the ArcGIS Explorer Resource Center to add the GeoNames Search task.

GeoNames Search searches the GeoNames (geonames.org) geographical database. It returns geo-referenced candidates from which you can create results or use for navigation. The database contains over eight million geographical names and consists of 6.5 million unique features.

Here we’ve entered The Loop in the GeoNames Search. Note that because ”The Loop” is such a common placename we’ve bumped up our maimum number of names to show from 10 to 20 to find the one in Montana. After we find it, we check it and then choose Create Result.

Next we enter Swiftcurrent Pass, and create another result.

And now our map has all three locations, one found using Find Place, and the other two found using GeoNames Search.

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