ArcGIS API for Silverlight/WPF public beta, media galleries released

Try the public beta of the ArcGIS API for Microsoft Silverlight/WPFExciting things are happening on the eve of the 2009 ESRI Developer Summit! Today the ArcGIS API for Microsoft Silverlight/WPF went into a public beta. This API allows you to build interactive Internet and desktop GIS applications using Microsoft’s Silverlight and Windows Presentation Foundation (WPF) technologies.

Try out the beta API using the online SDK, where you’ll find samples, introductory help, and an API reference. There’s also a Silverlight/WPF Code Gallery that already contains a Flickr mashup you can try.

If you encounter a bug when working with the beta, or if you just have a suggestion for improving the usability of the API, please report it to the ArcGIS API for Silverlight forum or the ArcGIS API for WPF forum. We look forward to hearing your feedback as we move the API toward its official release.

The Silverlight/WPF API wasn’t the only addition to the ArcGIS Resource Centers today. You may have also noticed some new “Media Gallery” pages in the online SDKs. These contain videos and other presentations to help you learn the APIs using a variety of media. Visit this post on the ArcObjects Development Blog to learn more about the media galleries and how to access them.

Happy coding, and best wishes for your travels if you’re joining us in Palm Springs next week!

Contributed by the ArcGIS Server software development team

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New Geodatabase SDK Article: “Common Geodatabase API Programming Mistakes”

We’ve added a new article to the Geodatabase SDK entitled “Common Geodatabase API Programming Mistakes”. It’s a list of mistakes we’ve seen a lot of users make and that will cause either unwanted behavior or a performance hit. This is going to be a living document – as our users come to us with questions or problems we’ll be adding to this accordingly.

The article can be found here

On Monday afternoon at the 2009 ESRI Developer Summit we’ll be presenting a pre-summit seminar called “Developer’s Guide to the Geodatabase”. A lot of the material in this article will be referenced during that presentation. Hope to see you there.

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Media Galleries come to the Resource Centers

We are proud to announce that we have recently updated the Resource Centers to include Media Galleries!  The main resource you will find in the galleries are videos, but you might also find Power Point Presentations and code files that are associated with certain entries.

  Media Galleries

These videos are classified into three categories :

  • Presentations: Recordings from various conferences and public events
  • How to: Get a tour through various code gallery entries or learn how to accomplish specific programming tasks
  • ESRItv: get a behind the scenes look at our software straight from the development teams

So far, the following community areas have galleries:

ArcGIS API for JavaScript
ArcGIS JavaScript Ext. for the Google Maps
ArcGIS JavaScript Ext. for Microsoft Virtual Earth
ArcGIS API for Flex
.Net ADF
Java ADF
ArcGIS Mobile
ArcGIS Desktop
Model and Script
ArcGIS .Net Engine
ArcGIS Java Engine
Water Utilities

So be sure to visit the galleries and take a peek.  We have more videos on the way, but feel free to provide feedback through ratings and comments.  And lastly, don’t forget to subscribe to the RSS feeds so you can be automatically notified of activity on the site.  

Thank you!


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How can you tell what map scales are shown for online maps?

By Aileen Buckley, Mapping Center Lead

Zoom Levels Thumb

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 Continue reading

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The XML Schema of the Geodatabase

ArcGIS provides the ability to transfer geodatabase data using XML.  With the ArcGIS XML format, you can import and export all items and data in a geodatabase such as domains, rules, feature datasets, and topologies.

An XML document containing geodatabase data can be validated against the XML schema using automated utilities. Working with a geodatabase through XML allows for better data interoperability and 3rd party tools can import data from these files or can export their data in these formats.

XML documents are defined by an openly published XML Schema. A document describing the XML schema for the Geodatabase is available for download here.

The purpose of an XML Schema is to define the legal building blocks of an XML document.  An XML Schema describes the structure of an XML document. The XML Schema language is also referred to as XML Schema Definition (XSD).

An XML Schema:

  • Defines elements that can appear in a document
  • Defines attributes that can appear in a document
  • Defines which elements are child elements
  • Defines the order of the child elements
  • Defines the number of child elements
  • Defines whether an element is empty or can include text
  • Defines data types for elements and attributes

These XML Schema elements define the format of an XML document. There are four types of XML documents that can be created and supported in ArcGIS.

XML Workspace Document

  •  Exporting a geodatabase to XML generates a workspace document.  The XML element Workspace in the XML Schema contains two child elements, WorkspaceDefinition and WorkspaceData.  The WorkspaceDefinition contains the schema of the geodatabase e.g. the fields of the feature classes. The WorkspaceData section contains the the actual geographic data.

XML RecordSet Document

  • The rows from a single feature class or table can be exported as simple features to a XML RecordSet document.  The features are exported as simple features, and no additional geodatabase-related information is written to the output file, e.g. topology rules (this is analogous to exporting a feature class to a shape file).

XML Data Changes Document

  • The ArcGIS disconnected editing framework allows you to check data out of aspects of one geodatabase into a different geodatabase, and then edit the data without having a live connection to the parent geodatabase.  Once the editing is done, it is possible to export only the changes (not all the data) to an XML file. This file can be used to subsequently transfer or check in the changes to the parent geodatabase. This file contains the inserted, updated and deleted features for each changed dataset. An XML Data Changes Document is also be used to transfer changes for one-way and two-way replicas for certain replication workflows.

XML Replica Document

  • Creating a replica from ArcSDE generates a replica document.  The XML replica document can only be created using our replica tools. The resulting replica document can be imported to ArcSDE using the Import XML Workspace Document Tool.


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I Want You…to vote for new tools

 by Kyle Watson 

The ArcGIS Business Analyst team creates new software tools and functionality by monitoring industry trends and listening to the needs of our user base.  So here’s a new tool concept we’d like to run by you and ask – would you use it?

Feature name:  Buffer Drive Time Trade Areas

Feature concept:  Create a Drive Time Trade Area not from one starting point, but from a polygon…and remove the interior polygon.


Real world application:  Two scenarios come to mind here. 

  1. Commercial Development – Let’s say you are targeting a commercial redevelopment area for new shops and restaurants, maybe an old airport or brownfield.  You’ve drawn a trade area around the airport edges to analyze the demographics, but what good does that do you when there is no data within the old airport area?  With the Buffer Drive Time tool you can create a trade area around the airport in all directions to determine how much area you cover within a specified distance.  Since the original polygon (airport) is removed, that area is not factoring into your analysis.
  2. Franchise Development – Let’s say you are in the quick service restaurant industry and you are looking to add a new franchise.  To avoid market saturation your company criteria states that any new franchise can be no closer than 15 minutes drive time from an existing franchise trade area – not the franchise, but the trade area around the franchise.  You can then analyze competitors, etc. ONLY around your existing trade area, not within it.

Can this be done now in ArcGIS?:  Well, yes it can…but it’s not one step.  You’d need to use a combination of Network Analyst, GP Tools such as the ArcInfo Erase tool, etc.  Time is money, and we are always interested in useful tools which save you time.

So let’s vote:  Would you use a feature like this?  Add your take to the comments field and feel free to email me. Any other tools you’d want to see in the product?  Lemme know.

 All The Best,


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Explorer 900 at the BPC/DevSummit

For those planning to attend the upcoming BPC/DevSummit, there’s lots of ways to see and learn more about ArcGIS Explorer 900.


 Here’s the Explorer schedule of events, in order by date and time:

Monday, March 23, 8:30 a.m.
Presummit seminar: Introducing and Implementing ArcGIS Explorer 900

Tuesday, March 24, 2:00 p.m.
Demo Theater:  ArcGIS Explorer 900 Developer: A truly managed experience

Tuesday, March 24, 5:00 p.m.
Meet the ArcGIS Explorer 900 Development Team

Wednesday, March 25, 10:00 a.m.
Demo Theater: Using application configurations to roll out a customized ArcGIS Explorer 900 experience

Wednesday, March 25, 2:45 p.m.
Technical Session: Introducing and Implementing ArcGIS Explorer 900 – Part I

Wednesday, March 25, 4:30 p.m.
Technical Session: Introducing and Implementing ArcGIS Explorer 900 – Part II


ArcGIS Explorer will also be featured in the ESRI Showcase. The showcase is a great place to get a more detailed and hands-on look at Explorer 900, and meet with development team members to get specific questions answered.

Monday, March 23, 11:00 a.m. to 7:00 p.m.

Tuesday, March 24, 12:30 p.m. to 6:00 p.m.

Wednesday, March 25, 10:30 a.m. to 4:30 p.m.


ArcGIS Explorer 900 will also be shown during the plenary sessions at both conferences:

BPC Plenary Session – Sunday, March 22, 8:30 to noon.

DevSummit Plenary Session – Tuesday, March 24, 8:30 to 11:45 a.m.

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Lidar Solutions in ArcGIS_part4: Estimating Forest Density and Height

This blog post is written by Clayton Crawford, a Product Engineer in the Software Products Group’s 3D Team in Redlands.

This is the fourth in a series on Lidar Solutions in ArcGIS.

Estimating Forest Canopy Density and Height

Canopy density and height are used as variables in a number of applications. These include the estimation of biomass, forest extent and condition, and biodiversity. Canopy density, or canopy cover, is the ratio of vegetation to ground as seen from the air. Canopy height measures how far above the ground the top of the canopy is. Lidar can be used to determine both.

What follows are steps to calculate canopy density and height from lidar points. First, you need lidar that’s been classified into ground hits (bare earth) vs. non-ground hits. This type of classification is usually performed by your data provider. Secondly, you need to consider when the lidar was collected and the type of vegetation in the study area. If there are a lot of deciduous trees and the data collection was performed during leaf off, then the density calculation is not going to work.

Loading points into the Geodatabase
To calculate canopy density load the ground, or bare earth, lidar points into one multipoint feature class and above ground points into another. Assuming your data are in LAS format, you do this with the LAS To Multipoint tool. Specify the proper class codes to filter on. Here are the LAS class codes as defined in the LAS 1.1 Standard:

Any LAS file made in the last few years should use these codes if the points have been classified. Unfortunately, there’s still some ambiguity in the standard. For example, we know class ‘2’ is ground but class ‘8’ is ground as well. Class ‘8’, or model key, points are a special set of ground points used for contouring or other application requiring a thinned set of ground points. Whether you have them depends on how the data was processed. If you don’t know specify both classes. If it turns out there aren’t any model key points it won’t hurt. Vegetation has a similar issue. Sometimes vendors place everything that’s above ground into class ‘1’ because they haven’t performed a more detailed classification on them. So, if you’re unsure of the specifics of your data’s classification, load non-ground points using classes 1, 3, 4, and 5; that’s a reasonable catch-all to get your vegetation points. Note: If buildings or other manmade non-ground features are in class ‘1’ you’ll get them too and they’ll skew the results somewhat.

Calculating the density
The most effective way to determine the canopy density is to divide the study area into many small equal sized units. Do this through rasterization. In each raster cell you compare the number of above ground hits to total hits. The trick is to figure out an appropriate cell size. It needs to be at least 4 times the average point spacing. You can go larger but not smaller.

1. Use the Point To Raster tool on the above ground points with the COUNT option.


2. Convert any resulting NoData cells to 0 so that subsequent operations treat zero points in a cell as 0. This is accomplished using the Is Null tool followed by Con.


Next use the Con Tool

3. Repeat steps 1 and 2 with the ground points.

4. Add the above ground and ground rasters to get a total count per cell using the Plus tool.


5. All the rasters we’ve made so far are longs. We need one to be floating point in order to get floating point output from the Divide function that we’ll use in step 6. Do this by sending the output from Plus through the Float tool.


6. Now use the Divide tool between the above ground count raster and the floating point total count raster. This gives us the ratio from 0.0 to 1.0 where 0.0 represents no canopy and 1.0 very dense canopy.

The following image represents canopy density. The lightest areas have little to no vegetation. These are areas where a large percentage of lidar shots could ‘see’ the ground. The dark green areas, where lidar could not penetrate to ground as well, indicate denser vegetation canopy.

Calculating the height
To determine canopy height you’ll need to subtract the bare earth surface (DEM) from the 1st return surface (DSM). Take a look at a previous blog to learn how to make these surfaces. Find it at this link: Creating raster DEMs and DSMs from large lidar point collections.

Once you have your first return and bare earth rasters the Minus tool gives you the difference which, over forest, represents the canopy height.

The following image represents canopy height above ground. It ranges from blue for little to no height, to orange which is the tallest.

Lidar can be used to calculate the density and height of vegetation. This is useful for a variety of purposes including biomass and carbon estimates as well as forest management.

That concludes part four of Lidar Solutions in ArcGIS. Subscribe to this blog or check back in a month or so for a discussion on the creation of intensity images from lidar.

Posted in Analysis & Geoprocessing | Tagged , , | 1 Comment

Locators now available

3/16/09—Address locators for Europe and North America, and a world places locator are now available on the ArcGIS Online Task Server. These free tasks are available to use in your ArcGIS applications.

The geocoding and place finding capabilities are based on Tele Atlas 2008 reference data for North America and Tele Atlas 2007 reference data for Europe. The address locator services support single address, reverse, and batch geocoding of up to 1,000 batch geocodes in a year. For external commercial use of ArcGIS Online tasks, or if you want to perform more than 1,000 batch geocodes in a year, you must purchase a subscription.

For information on using the locators with the ArcGIS software of your choice, see Using free geocoding tools on the task server.

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Ok, so what's coming in ArcGIS Explorer 900?

There’s a high level overview of what’s coming in ArcGIS Explorer 900 that’s recently been published on the ArcGIS Explorer Web pages on

At the upcoming Business Partner Conference and Developer Summit we’ll be hosting a presummit seminar and a double technical session detailing the 900 release.

You’ll also get to see ArcGIS Explorer 900 during the plenary presentations, and also at the ESRI Showcase where you’ll have an opportunity to meet and talk with the ArcGIS Explorer team.

We’ll be looking forward to seeing you there, and talking in more detail about ArcGIS Explorer 900.

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