additional geowankery

Google Maps can only handle KMLs with points, lines, and polys. Ground overlays are strictly verboten. However, you can overlay images in Google Maps using mapplets. The process is simple and well documented. The basic steps are: 1. write your mapplet, the example below contains all the tags that the example on google doesn't show for your cut-n-paste enjoyment: <?xml version="1.0" encoding="UTF-8"?> <module> <moduleprefs title="1929 Map of San Antonio, Texas" height="300"> <require feature="sharedmap"> </require></moduleprefs> <content type="html"><![CDATA[ <small> This is a georeferenced map of San Antonio, Texas in 1929. The original map is at http://www.tsl.state.tx.us/arc/maps/images/map1052a.jpg </small> <script> var map = new GMap2(); map.setCenter(new GLatLng(29.4208378,-98.4938900), 12); // ground overlay var boundaries = new GLatLngBounds(new GLatLng(29.3400022,-98.5543116), new GLatLng(29.5016733,-98.4334683)) var oldmap = new GGroundOverlay("http://www.tsl.state.tx.us/arc/maps/images/map1052a.jpg", boundaries) map.addOverlay(oldmap) </script> ]]></content> </module> 2. Upload your code to a server or to Google page creator. 3. Install it on Google Maps directory. 4. Share the map using a long url like this: http://maps.google.com/ig/add?synd=mpl&pid=mpl&moduleurl=http://www.geouptime.com/mapplet_san_antonio_1929.xml Google will ask you if you want to add it to maps (I assume it means your maps). Clicking on Add it to Maps opens the mapplet. Voila!

Making historic information more available

I write on another blog documenting the history of my house in San Antonio, Texas. As part of the research we found that there was streetcar service close the house. A quick search turned up a map of the streetcar lines at the Texas Transportation Museum. I thought it would be neat to overlay that map over other map services. I first tried to georectify the Texas Transportation Museum map using Metacarta Labs Map Rectifier, but the quality of the scan was too poor to successfully add enough ground control points for a good warp. Another search turned up a much better scan of a 1929 map at the University of Texas Perry-Castaneda Library Historic Map collection. This map was scanned at a very high resolution and it was easy to create a sufficient number of ground control points to use a cubic fit georegistration using Metacarta's Map Rectifier. The result was a 215mb tif file which I was able to download. Thanks Metacarta! The next step was to trace the streetcar lines using uDig. I used version 1.1.1 which is verrrry slooowww when it comes to handling largish tif files. I heard that raster handling is improved in 1.2 beta as well as more digitizing tools, so you might want to use that. Once I figured out the editing tools it was fairly easy to digitize the streetcar lines. Always the critic, I have to say the the editing tools could use some context sensitive menus available through a right click. I saved the streetcar lines as a shape file and I saw that uDig has a number of tools for cleaning up the data and validating the output. Nice. I converted the shape file kml using ogr2ogr. The first time I tried it ate my shape file, no idea why. I noticed that my gdal install was way out of date (version 1.4), so I installed version 1.6 for OS X from the Kyng Chaos Wiki. Using ogr2ogr was straight forward:

ogr2ogr -f KML sa_streetcars.km streetcar_lines.shp

I tweaked the KML in a text editor so that each streetcar line was a consistent color. Then I uploaded it to myGoogle maps. The 1929 map overlays fairly well but not exactly. I think it was important to use a historic map for digitizing the lines instead of using a modern map such as Open Street Map, Google Maps, or the Census Bureau's TIGER street files because there have been many changes to the street network since the streetcars were in service. The lines may not overlay perfectly, but I think its a better representation. Here's the data and final map:
View Larger Map

orchestra practice

Yesterday was the first practice for my church orchestra.  I was wondering who would show up and it turned out to be a diverse group. 

• 3 cellos
• 3 violins
• 2 violas
• 1 oboe/english horn
• 1 flute
• 3 clarinets 
• 2 alto saxes

We actually sounded OK and I was more or less able to keep up/play in time with everyone.  The director is our church's choral director but she did a great job mixing and matching sections of the different pieces.   I was mighty pleased since I haven't played in an orchestra since junior high.  One of the other cellists even asked me if I wanted to get together and work on duets.  I am so jazzed.

subtle reminders

I was in Chicago on Tuesday and I stayed at the Kimpton Allegro.  Lo and behold there was a picture of what looks like an x-ray of a cello in my room!  Just another reminder to get may butt in gear with the Prakticello build.

I've found a tail piece on ebay so far, and I'm looking for a neck and fingerboard.  Finding a source for spruce is turning out more elusive.

Building a Prakticello: The Plans Arrive

This is a departure from my cheesy java bits, but I'm building a Prakticello; so this will be a build log of sorts. 

I travel a bit and I really miss cello practice when I'm out of town. I thought about getting a silent or electric cello but none of them seem to be overhead compartment friendly except the Ned Steinberger electric cellos. The NS cellos look awesome, and in my imaginary world I can see myself playing Bjork or the Clash's "Straight to hell" and becoming a rock star cellist. But I bought a cello over the summer, so I'm just not ready to plunk down $2K for another instrument. Once again cheapness (or more kindly, thrift) crushes my dreams. Another mitigating factor is that I joined the Christmas orchestra at my church. While the pieces are not particularly difficult, most of the songs are in F major and I'm still kinda banging around C major in the Suzuki 2 pieces.  Yeah, I know I should practice my scales more often. Anyway, I don't want to sound like an ass because my extension sucks. I ordered a set of plans from the inventor of the Prakticello, Mr. Ernest Nussbaum. The plans were written circa 1985 and they have the sort of charm of plans ordered from the back of Popular Mechanics. The plans are hand drawn (as opposed to be done in a CAD package) and the hand lettering is charming, not Leroy lettering but you can see faint lines drawn in to guide the lettering. The plans come with a 22 page instruction manual written in a Courier font adding a typewritten charm. You can imagine Mr Nussbaum banging away on an IBM Selectric. The plans are actually for a Traviola, which is the electrified version of the Prakticello. They contain the build of materials and general instructions which include building a small amp. For my purposes, I'll stick to the silent cello build for now. There are a couple of photos of the Prakticello in the manual and the website, but they really don't do the Prakticello justice. I found these pics on a discussion board:

checking for well formed documents in OS X

I sometimes have to generate XML documents from some random source of data. It's typically a one off task, so I just write a quick program. However, I usually get the format wrong or forget a special character. OS X (and linux) happens to have a neato utility for checking for well formedness called xmlwf

Making GeoWebCache authenticate to a WMS

GeoWebCache is a java implementation of TileCache.  Geowebcache does not connect to secured a WMS, so I added support for it (yay! for open source).

The WMS GetMap requests are in WMSMetaTile.java (../geowebcache-0.8.3/src/main/java/org/geowebcache/layer/wms).  I thought that the best place to put the username and password was in the WMS service url, which is set in the properties file for the layer (../geowebcache/WEB-INF).  This takes the form of http://username:password@www.mapserver.com/ .  

Alternatively you can also put username and password in the vendor parameters, but that could get dodgy if you have other vendor parameters.

From googling RFC 2716 related documents, the username and password has to be sent in the http Authorization request header in the form of username:password encoded in base64.  Real secure, huh?

So here's the code:

    private void forwardRequest(WMSParameters wmsparams, String backendURL,
        WMSLayerProfile profile) throws IOException, ConnectException,
        ServiceException {

    // extract username and password from service url if there
    String encoding = null;
    int upTest = backendURL.indexOf("@");
    if (upTest>0) {
     String[] temp = backendURL.split("@");
     backendURL = "http://"+temp[1];
     String usernamePassword = temp[0].substring(temp[0].lastIndexOf("/")+1,temp[0].length());
     encoding = new sun.misc.BASE64Encoder().encode (usernamePassword.getBytes());    
    }

    //Get user name and password from vendor parameters
    //Vendor parameter key is "logon"
    //Need to add iterator in case of multiple vendor parameters
    /*
    if (profile.vendorParameters!=null) {
       String[] temp =profile.vendorParameters.split("=");
       if (temp[0].equalsIgnoreCase("logon") {
          String usernamePassword= temp[1];
          //usernamePassword = usernamePassword.substring(usernamePassword.indexOf("=")+1,usernamePassword.length());
          String encoding = new sun.misc.BASE64Encoder().encode (usernamePassword.getBytes());    
       }
    }
    */
         
    // Create an outgoing WMS request to the server
    Request wmsrequest = new Request(backendURL, wmsparams);
    URL wmsBackendUrl = new URL(wmsrequest.toString());
    log.info("the request: "+wmsrequest.toString());
    URLConnection wmsBackendCon = wmsBackendUrl.openConnection();

    //if username and password required set header
    if (!(encoding==null)) {
       wmsBackendCon.setRequestProperty  ("Authorization", "Basic " + encoding);
    }

...

bits and stuff

Some bits I always seem to forget. Splitting a delimited line of text in bash line = a|b first=${line%|*} second=${line#*|} echo $first echo $second Post in curl (OS X) curl --data-ascii "var1=one&var2=two" http://server.com/myapp

in the belly of the beast

I write this from my Google tent, pitched in the Google courtyard, connected to the intarnets using Google's network; and of course using Google software. I'm here for wherecamp catching up on all things related to geo and the web. Observations of the campus: +1 for the heated toilet seats +1 for the yummy soy yogurt +1 for the schweet tent swag with the Google logo and the slogan "I'm feeling lucky." odd moment - watching Google employees pile out of cars on a Saturday night to do their laundry at the Google campus Observations on wherecamp: People are posting and editing the wiki here and here.

Embedded tomcat and launch4j FTW

I've been meaning to get around to this for years. Using this example, I compiled it with my webapps and then used lauch4j to create a windows executable wrapper. Throw in a jre and some data and I'm good to go. Now I just give the live demos to the sales people and clients on a USB stick without having to go through the install or setting it up on a web server. Here's the code example:

import org.apache.catalina.*;
import org.apache.catalina.connector.*;
import org.apache.catalina.realm.*;
import org.apache.catalina.startup.*;


public class EmbeddedTomcat
{
  // Instance variables:
  private String    name;
  private int       portNumber;
  private Embedded  embedded;
  private Engine    baseEngine;
  private Host      baseHost;
  private Connector httpConnector;
 
  /** Creates a new instance of EmbeddedTomcat */
  public EmbeddedTomcat(
    String name,
    int    portNumber)
  {
    this.name = name;
    this.portNumber = portNumber;
 
    init();
  }
 
  private void init()
  {
    MemoryRealm realm;
    Context     context;
    String      baseEngineName;
    String      hostName;
 
    embedded = new Embedded();
 
    // set default logger and realm
    /*
       FileLogger fileLog = new FileLogger();
       fileLog.setDirectory(".");
       fileLog.setPrefix(name);
       fileLog.setSuffix(".log");
       fileLog.setTimestamp(true);
       embedded.setLogger(fileLog);
     */
    realm = new MemoryRealm();
    embedded.setRealm(realm);
 
    // create an Engine
    baseEngine = embedded.createEngine();
 
    // set Engine properties
    baseEngineName = name + "Engine";
    hostName = name + "Host";
 
    baseEngine.setName(baseEngineName);
    baseEngine.setDefaultHost(hostName);
 
    baseHost = embedded.createHost(hostName, "webapps");
    baseEngine.addChild(baseHost);
 
    // RootContext
    context = addContext("", "ROOT");
 
    // ManagerContext
    context = addContext("/manager", "manager");
    context.setPrivileged(true);
    

   /* This is where you add your webapps*/

    //  GeoBrowserContext
    context = addContext("/geobrowser", "geobrowser");
    context.setPrivileged(true);
    
    // add new Engine to set of Engine for embedded server
    embedded.addEngine(baseEngine);
 
    // create Connector 
    httpConnector = embedded.createConnector((java.net.InetAddress) null,
        portNumber, false);
 
    // add new Connector to set of Connectors for embedded server, associated
    // with Engine
    embedded.addConnector(httpConnector);
  }
  
  
 
  public void start()
  {
    // start server
    try
    {
      embedded.start();
    }
    catch (org.apache.catalina.LifecycleException ex)
    {
      ex.printStackTrace();
 
      //fileLog.log("Startup failed");
      //fileLog.log(ex.getMessage());
    }
  }
  
  public void stop()
  {
    // start server
    try
    {
      embedded.stop();
    }
    catch (org.apache.catalina.LifecycleException ex)
    {
      ex.printStackTrace();
 
      //fileLog.log("Startup failed");
      //fileLog.log(ex.getMessage());
    }
  }
 
  public Context addContext(
    String path,
    String docBase)
  {
    Context c;
 
    c = embedded.createContext(path, docBase);
    baseHost.addChild(c);
 
    return c;
  }
 
  public static void main(String[] args)
  {
    new EmbeddedTomcat("RedSpider", 8080).start();
  }
}