Monthly Archives: November 2008
There is new documentation available which talks about some best practices when using the compress command while also employing geodatabase replication. Compress is a process run periodically by an ArcSDE administrator to reduce the size of the geodatabase and improve performance. Replicas in the ArcSDE geodatabase can affect the compress process. This paper describes best practices for achieving an effective compress when there are replicas.
It is recommended that you first have an intermediate understanding of ArcSDE, versioning and replication before reading the paper.
To have a look at the paper, click HERE
Versions 1.2 of the
available for you to use. To get started, just change the version number in the
script tag that references the API.
Google Maps example:
Virtual Earth example:
Below are some of the new features in each API:
Geometry service can provide label points
The ArcGIS Server 9.3
Service Pack 1
geometry service can calculate a point that lies within a polygon and
expose that point through REST. Both the Google Maps and Virtual Earth
extensions have new methods that take advantage of this functionality. You can
place text or some other marker at this point as a way of labeling the polygon.
Geometry service can calculate spatial relationships
In both the Google Maps and Virtual Earth extensions, methods have been added
that allow you to calculate spatial relationships (such as “touches”,
“overlaps”, “intersects”) using the geometry service. Previously you could use
queries to calculate some spatial relationships, but the geometry service
provides more relationship types and doesn’t require that the geometries come
from ArcGIS Server. The geometries can just be two sets of graphics that you
get from a Web service or derive from task results. To use this functionality
your geometry service needs to be running on ArcGIS Server 9.3 Service Pack 1.
Image service layers supported (Google Maps only)
ArcGIS Server image services as layers in Google Maps. Image services come from
standalone raster datasets or .iscdef files produced by the
ArcGIS Server Image Extension (formerly Image Server).
The Google Maps extension also has a few new methods on DynamicMapServiceLayer that are listed here.
Support for Image Services
You can add ArcGIS Server Image Services to the map using ArcGISImageServiceLayer. Image services represent file-based raster datasets or raster collections published with the ArcGIS Server Image extension. You can control the image type, compression type for JPG, image bands, and interpolation type.
Support for Dojo 1.2.
More flexibility with cached and dynamic layers
You can now define which tile levels of a cached service are exposed in the map. For example, you may want to use ArcGIS Online data for small scales only, then switch to your own cached data at large scales. Or you may want to make a cached service available at large scales only in order to focus the map on a certain geographic area.
You can also force dynamic maps to conform to the scale levels in a tiling scheme. This allows you to show a cached map at small scales, then easily switch to a dynamic map at large scales.
Refreshable map layers
Map service layers have a refresh() method. This is useful if back-end editors are modifying the data and you want to ensure the end user of the application sees the most recent data from the server.
Improved graphics performance
The performance of the graphics layer is improved when adding a large number of graphics to the map.
Projection of dynamic map services on the fly
Dynamic map services can be projected on the fly to match the spatial reference you set for the map. Previously, the spatial reference was defined by the base layer. Now the map can be defined using any spatial reference. Valid only with dynamic map layers.
New methods for the geometry service
GeometryService has new methods that allow for creating points in polygons for labeling purposes, and determining spatial relations of geometries. These geometries do not have to come from a map service; they can be geometries returned from a task or a query to a non-ArcGIS Web service.
The following bugs have been fixed in version 1.2:
- NIM036958 Style Attributes (STYLE_DASHDOTDOT and STYLE_NULL) of SimpleLineSymbol now work as expected.
- NIM036833 Graphic.attribute names that contain decimal points (mytable.area) can be used in an InfoWindow through the Graphic.InfoTemplate.
We’d be happy to read your feedback about version 1.2 as comments to this post.
Geography Awareness Week was established in 1987 when U.S. President Ronald Reagan signed legislation that established the third week in November as Geography Awareness Week. Geography Awareness Week is sponsored by the National Geographic Society and other geographic organizations at the national, state, and local level.
We’ve received some screenshots and descriptions of Explorer being used on GIS Day and throughout this week. If you have more examples that you’d like to share, let us know by sending a screenshot and description via e-mail to email@example.com
This first example is from Adam Pittman, who prepared a presentation for the fourth grade class at Cambridge Elementary School in San Antonio, Texas. The students are learning about explorers of North America, and ArcGIS Explorer was used to look at the explorations of Coronado, Lewis & Clark, and LaSalle.
Here’s a screenshot of the Lewis & Clark exploration ending up at Fort Clatsop, Oregon, where Capt. William Clark wrote in his journal “Ocian in view! O! the joy.” While they weren’t quite at the ocean, they were close, having reached the Columbia River estuary. Various camps are shown along the route.
Coronado travelled up from Mexico, heading to the Grand Canyon and then heading east through Texas and up to Kansas. He stopped just outside Lindsborg, Kansas, erecting a small fort on top of a hill, shown below. The fort has been rebuilt and can be seen in Explorer’s default map.
GIS tools were used to analyze terrain and view other layers of information that could have helped these early explorers, like weather, topography, vegetation, and others.
And Ray Carnes presented at the Highland (California) Library and Environmental Learning Center as part of a “See Highland Through Maps” GIS Day exhibit. Shown below is a part of the city with average household income information. Images like these helped visitors understand the characteristics of their local community.
Of the individuals that participated, it’s clear that Visual Studio 2005 with .NET 2.0 is the most popular IDE for ArcObjects development today. 50% of the community are developing with this configuration. The next most popular configuration is Visual Studio 2008 with .NET 3.5 at 32%.
A smaller percentage are taking advantage of the Visual Studio 2008 IDE improvements, but still building on top of the .NET 2.0 framework. This is surprising given that .NET 3.0 and 3.5 didn’t undergo any major architectural changes (still uses the .NET 2.0 CLR) and are considered an additive release. We would be interested in hearing more feedback about this!
There are limitations, but another interesting fact was that very few (2%) of the respondents identified that they were using Visual Studio Express. And of course, there are still a few (3%) implementing Visual Studio 6.0.
On that note, for all VB6 and VBA developers looking to transition to .NET, we are releasing a number blogs and videos on the migration process very soon. Keep your eyes posted.
In the mean time, let’s turn to the Java developers in the next poll and see what IDE they are using.
Thanks for the feedback!
To follow up on our last post, this is just a heads up to tell you that Derek Law’s podcast for Migrating to the Geodatabase is now online. The podcast talks about how to migrate existing data into the geodatabase. Derek goes over migration details for 5 of the more common data types: tables, shapefiles, CAD, coverages and imagery.
The podcast is intended for GIS managers and GIS analysts who are new to working with geodatabases and would like to learn more about how to convert and use their existing GIS data in a geodatabase.
If you are interested in hearing the podcast or reading the transcript, you can find both HERE
The ArcGIS Explorer default map, and maps and layers you can discover on the Explorer Resource Center, are created using ArcGIS Online services. Behind the scenes these have been authored using ArcGIS Desktop, and are powered by ArcGIS Server.
We’ve chosen a subset of all of the available ArcGIS Online services to include on the Explorer Resource Center, but you can connect directly to ArcGIS Online and shop around for more. Here’s how…
Go to File > Open, and choose Servers. You’ll see a list of the available connections you can make across the top. Choose ArcGIS Server (since the ArcGIS Online services are ArcGIS Server based) and type the following connection URL:
You’ll see a list of all of the available services, many of them organized into folders.
At the bottom left of Open Content you’ll see a link to the Help on Opening Content that includes a legend describing the icons you’ll see:
Since Explorer is a globe, the globe services will be optimal. Many of the listed services are intended for use in ArcGIS Desktop, but any services you find will work just fine.
In this example, let’s click to open the NASA CloudCover_World, and choose Space:
We’ve just added a cloud cover layer to our map. There lots of content to choose from, so try browsing for others you may find of interest.
A key consideration when designing a custom web control is where the control’s logic will execute. While all the logic could be put in either the client or the web tier, the best approach is usually to place some logic in each tier. User interface data and operations should usually be situated in the client tier, while data retrieval and heavy computational logic should (and often must) reside in the web tier. Distributing the control in this way maximizes the use of client resources and reduces server load.
Additionally, in order to minimize network traffic, client tier functionality should initiate server tier logic only when necessary (for example, to query a database housed in the web tier). Adhering to this architecture enables the development of controls with rich and responsive user interfaces.
Given the advantages of this architecture, the question becomes one of implementation. How can you efficiently create an implementation that is intuitive, maintainable, extensible, and re-distributable? One effective approach is to create a scriptable ASP.NET server control that inherits from the Web ADF WebControl.
This is the approach we used when implementing the Web ADF controls, and we recently added a tutorial to the online help describing how to develop scriptable controls. The tutorial illustrates implementing a MapCoordinateDisplay control, which displays the current position of the mouse cursor over a buddied Map control.
Contributed by the ArcGIS Server .NET software development team
Yesterday nearly 5 million Californians living near the San Andreas fault participated in an earthquake disaster preparedness drill called the ShakeOut, which we mentioned in our post yesterday. The earthquake scenario included a 7.8-magnitude earthquake along a 190-mile stretch of the fault starting at the Salton Sea and stretching northwest.
To understand the demographics of the most impacted areas in the scenario, we opened the USGS earthquake simulation shake intensity map (published as a KML) and added it to Explorer. Here’s the view of the quake intensity map looking north along the southern California Coast. The red areas are the areas with the highest predicted intensity.
We used the Business Reports task (powered by ESRI’s Business Analyst Online), available on the Explorer Resource Center, to delineate the boundary around the highest intensity areas. We used that boundary to generate the report, shown here:
The graphic demographic profile is the one we chose, and there are many different kinds of reports to choose from (some are free, some require a subscription). The report showed that over 6 million households are located in the high intensity area, roughly evenly distributed by age and income, with %50 of the owner occupied homes having a value greater than $400,000, and %40 having a value of greater than $500,000.
By Aileen Buckley, Mapping Center Lead
We recently got a question on Ask a Cartographer that related to the use of a restricted color ramp. The person asked, “Is there an easy way that I can make all the counties in one state variations on one hue, but each state a different colour so that the map readers can easily distinguish between states and counties?” The solution is a restricted color ramp and it can be used in many different situations. Continue reading