GeoLab

GeoLab Releases Wind Buddha Version 1.1: A Free ArcGIS Silverlight Wind Application

admin — Wed, 16 Sep 2009 04:59:35 +0000

DENVER, CO, September 16, 2009 — Wind farm projects are now re-emerging after a six-month lull. Energy companies in multiple states have recently received large federal cash grants for wind farms, and notable investors such as Morgan Stanley and Citigroup are making large investments in wind farm opportunities. With this in mind, GeoLab announces the release of Wind Buddha™, a free Silverlight wind application that enables users to locate and analyze areas of wind potential.

Wind Buddha™ version 1.1 provides a macro level view of the wind energy potential for most of the United States categorized by a wind power classification. System users can locate areas of interest by U.S. address, or by manually selecting a point on the map. In addition to providing energy potential, the Buddha also offers non-private land ownership information, transmission line data, current wind information, and live NEXRAD radar weather tracking.

The Wind Buddha™ application utilizes the Environmental Systems Research Institute (ESRI) ArcGIS® Silverlight Control with industry standard Open Source tools including: GeoWebCache, GeoServer, PostGIS, and the Open Street Map dataset. Representational State Transfer (REST) and the Windows Communication Foundation (WCF) services have also been integrated into the application, in preparation for expansion into additional web clients. For more information, visit TheWindLab.com.

With the Wind Buddha™ release, GeoLab continues to expand upon its commitment to merge commercially available GIS software with Open Source software for energy related applications. The demand for Rich Internet Applications (RIA) such as Silverlight technology usage in the Geo-Spatial user community continues to rise. GeoLab has chosen to utilize strong suits of the Silverlight technology, with the benefits of managed code on the .NET platform. Open Source server side GIS components provide an ideal accompaniment to the client side ESRI and Microsoft® solutions.

GeoLab is a U.S. based GIS Consulting firm focusing on full GIS design, software lifecycle development, and system management. GeoLab specializes in the integration of Commercial and Open Source technologies, and provides affordable and scalable system solutions. For more information, visit TheGeoLab.com.

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GeoServer and GeoWebCache for Virtual Earth Silverlight

admin — Wed, 25 Mar 2009 00:57:15 +0000

Virtual Earth Silverlight : GeoWebCache GeoServer Tile Overlays

This Article gives a nod to three sources that made this happen:
1. Virtual Earth Tile System.
2. Chris Pietschmann’s article on VE Silverlight integration with Yahoo Maps, Open Street Maps, and Open Aerial Maps.
3. GeoWebCache Virtual Earth Examples.
To assist with configuration between GeoServer and GeoWebCache check my: configuration article.

Introduction

I’m sure there’s been a significant number of downloads already at old Microsoft for their Silverlight for Virtual Earth CTP just released last Friday. Interestingly enough, ESRI released their Silverlight for ArcGIS control the day before. I’m sure I will end up using that control, as it’s off to rave reviews, but currently am focusing on Virtual Earth. The below code really wasn’t that difficult, but it is important. GeoServer, being a free and Open Source platform, with its companion GeoWebCache, are an almost undeniable combination for many server side processes. I’m loving the combination, and with REST now solidly on the back end in GeoServer 1.7.3, Look Out. This article will look specifically at the C# code, URIs, and methods necessary to pull a tiling scheme in from GeoWebCache as a custom TileSource and overlay those tiles in Silverlight for Virtual Earth.

The Necessities

We’re basically going to follow Pietschmann’s lead with just a few twists on the URI that GeoWebCache already uses for its Virtual Earth AJAX control.
Let’s review the general approach:
1. Create a custom TileSource object inherited from Microsoft.VirtualEarth.MapControl.TileSource.
a. Define the URI to get those images.
b. Override the GetURI method on the TileSource.
2. Add the custom TileSource to the map.
a. Add a new MapTileLayer instance to the map.
b. Create an instance of your custom TileSource object.
c. Add that TileSource to your MapTileLayer.
d. Add the MapTileLayer to the Map’s children collection.
Step 1. tasks happen in the .xaml.cs and Step 2. tasks are in the .xaml itself. There are many variations on this.

Create a Custom TileSource

GeoWebCache has exisiting request services in place just waiting to scoop up what you’re willing to give it to get your tiles. There’s a couple of routes you can take with this:
1. the VEconverter object route which is more complex, but is informative, and potentially useful for other things.
2. the more direct Gmaps object route. VEconverter route’s C# code in xaml.cs

public class GWCtileSource : Microsoft.VirtualEarth.MapControl.TileSource
{
public GWCtileSource()
:base(“http://localhost:8080/geoserver/gwc/service/ve?layers=topp:states&format=image/png&quadkey={0}”)
{
}
public override Uri GetUri(int x, int y, int zoomLevel)
{
string veQuadStr = TileXYToQuadKey(x, y, zoomLevel);
return new Uri(String.Format(this.UriFormat, veQuadStr));
}
public static string TileXYToQuadKey(int tileX, int tileY, int levelOfDetail)
{
StringBuilder quadKey = new StringBuilder();
for (int i = levelOfDetail; i > 0; i–)
{
char digit = ’0′;
int mask = 1 << (i – 1);
if ((tileX & mask) != 0)
{
digit++;
}
if ((tileY & mask) != 0)
{
digit++;
digit++;
}
quadKey.Append(digit);
}
return quadKey.ToString();
}
}

As you can see in the first few lines of code, GWCtileSource inherits from the VE TileSource object. This is your custom TileSource now.
In the constructor of your custom TileSource object, the :base allows us to replace our URI request with the tile(s) we are going to want to show. The request string you are looking at is a typical basic GeoServer GeoWebCache request string http://localhost:8080/geoserver/gwc/service. The ve? tells us it’s a Virtual Earth request and the topp:states is a demo layer found in GeoServer. Much of this is explained in the configuration article mentioned above. However the quadkey= part is different than the AJAX Virtual Earth client. You don’t have anything sending the right quadkey list back over to GeoWebCache to get the tiles. We, however, need to dig a little deeper with this GeoWebCache route by using the x, y, and zoom levels in a different way.

public override Uri GetUri(int x, int y, int zoomLevel)
{
string veQuadStr = TileXYToQuadKey(x, y, zoomLevel);
return new Uri(String.Format(this.UriFormat, veQuadStr));
}

By overriding the GetUri method of the TileSource, we can grab the x tile location, y tile location and zoomlevel from this method, and push those into a Virtual Earth method to get the quadkey(s) we need. These keys are returned back to the TileSource, and we’re in business. The explanation on the TileXYToQuadKey can be found at the Microsoft source mentioned at the top of the article. Gmaps route’s C# code in xaml.cs

public class GWCtileSource : Microsoft.VirtualEarth.MapControl.TileSource
{
public GWCtileSource()
: base (“http://localhost:8080/geoserver/gwc/service/gmaps?layers=topp:states&zoom={2}&x={0}&y={1}”)
{
}
public override Uri GetUri(int x, int y, int zoomLevel)
{
return new Uri(String.Format(this.UriFormat, x, y, zoomLevel));
}
}

Your alternative approach is the above code. This was an approach I was looking in to as being more direct to the tiles, and Arne Kepp on the GeoWebCache ListServ verified it. We essentially cut out the middle man here, and use the Google Maps request string to get the tiles. On large requests, it may save you some processing overhead, but I think its important to be aware of both routes.

Add a new MapTileLayer instance to the map

I’m going to move quickly through this last part as it’s easy squeezy. Here’s the xaml:

xmlns=”http://schemas.microsoft.com/winfx/2006/xaml/presentation”
xmlns:x=”http://schemas.microsoft.com/winfx/2006/xaml”
xmlns:m=”clr-namespace:Microsoft.VirtualEarth.MapControl;
assembly=Microsoft.VirtualEarth.MapControl”
xmlns:local=”clr-namespace:SilverlightTestApplication”>

So, the XAML is doing what could also be done on the C# side of things. We’ve done it here, though. You can see we have added a MapTileLayer to the Map.Children and created an instance of the TileSource(s)GWCtileSource we declared in the C# code. The TileSource is associated with the TileLayer which is part of the map now. That’s it in a nutshell. Best of Luck.
Copyright GeoLab 2009.

Introduction to MapServer

admin — Sun, 20 Feb 2005 02:23:21 +0000

What is Map Server?

OpenSource development environment for constructing spatially enabled web sites.
Originally developed in 1994 at the University of Minnesota & funded by NASA ForNet project.
Builds upon other popular OpenSource or freeware systems. e.g. Freetype, Proj4, GDAL/OGR
Compiled as a CGI application.

MapServer Development History

1994 – Web-based Arc/Info AML
1997 – Version 1.0
1998 – Version 2.0 (Release as ForNet MapServer)
1999 – Version 3.0 (raster + truetype fonts added)
2000 – Version 3.3 (MapScript, PROJ4)
2001 – Version 3.5 (OGC, OGR, GDAL)
2002 – Version 3.7 (24bit image support)
2003 – Version 4.0 (Flash, PDF)
2004 – Version 4.4 (WMS compliant)

MapServer Features:

Vector Support – Shapefiles, ArcSDE , Oracle Spatial, etc. *The OGR module supports many other formats.
Raster Support – TIFF/GeoTIFF, EPPL7, ECW, Erdas, etc. *The GDAL module supports over 30 formats.
TrueType font support.
Map configuration file is used to create the cartography.
Map element automation (scalebar, reference map, and legend).
On-the-fly projection.
Feature labeling including label collision mediation.
Feature selection by item/value, point, area or another feature.
Support for OGC – WMS, WFS, and WCS.
Mapscript provides a robust development environment.
Image output as GIF, PNG, and JPEG.
Spatial database support with tools such as PostGIS provide a means to do spatial analysis on the fly and present the results.
Can be compiled with Mapscript Module. (PHP, Perl, Java, Python)
Runs on Linux, Windows, Unix, and even Mac OS.
Maintained by twenty or more developers around the world.
http://mapserver.gis.umn.edu

MapServer Disadvantages:

No integrated Geocoder. Try Google contest winner Geocoder
No automated clean up routine inherent to the software. Must write or obtain one.
No installation program for Windows. It’s piece meal, but works. * Breaking News…There is one now. Windows Installer
Linux installations are not for the faint of heart, but once accomplished opens up the potential for serious custom builds.
No inherent geoprocessing, but with a spatial DB one can run spatial SQL and present the results.
Hosting options are limited, but a minimal server is needed.
User base is weak in our neck of the woods here in AZ.

MapServer Windows Installation:

Get the latest binaries.
Read the README-Install.txt.
Copy package to C:\mapserver.
Copy mapserv.exe from “C:\MapServer\bin” to your web server’s cgi-bin directory.
Copy directory “Proj” to “C:\Proj” If you choose to put it somewhere else you will need a system variable.
Copy the dynamic link libraries (the files with .dll extensions) to your system directory. e.g. “C:\Windows\system32“
Restart your web server.
Test MapServer by typing “http://localhost/cgi-bin/mapserv.exe”on your browser. Success =“No query information to decode. QUERY_STRING is set, but empty.”
Get many other builds from DM Solutions including the PHP Module: Maptools