Using KML, XML, and XSL
to Create Google Earth
Applications: A Tutorial
Betsy Page Sigman and William Garr
Georgetown University
Southeast Decision Sciences Institute Conference
Orlando, Florida
February 22, 2008
Overview
1. The benefits of displaying data using
Google Earth/Google Maps (GE/GM)
2. KML and the creation of placemarks in
Google Earth/Google Maps
3. Use an Access database to create many
placemarks simultaneously
4. Create different styles of placemarks
based on the value of an attribute.
Why Use Google Earth/Maps to Show
Data
1) Allows the viewer to understand the data
more fully.
2) Can enable the viewer to use the data
more easily.
3) Gives a more comprehensive view about
how the data presented relate to each
other.
4) Can aid in decision support, due to the
properties discussed above.
Getting Information from a Placemark
1. From information listed on the placemark
(i.e. Address, Contact person, Phone,
Email, etc.)
2. From the geographic location of the
placemark.
3. From an attribute of the icon used (i.e.
shape, color)
XML
• XML stands for “eXtensible Markup
Language.”
• Extensible means that it can be extended
to create whatever tags you want.
How it differs from HTML
•
•
•
•
•
•
XML holds data
HTML presents data
XML is about what data is
HTML is about how data looks
XML is for data description
HTML is for data display
Example of XML
<note>
<to>Rebecca</to>
<from>Donald</from>
<heading>Remember</heading>
<reminder>Don’t forget your MIS
final</reminder>
Right now, this doesn’t
</note>
do anything. You’d
have to send it or
display it.
Simple KML File
1. <?xml version="1.0" encoding="UTF-8"?>
2. <kml xmlns="http://earth.google.com/kml/2.0">
<Placemark>
3. <description>Washington, D.C.</description>
4. <name>Washington, D.C.</name>
5. <Point>
6. <coordinates>-76.5427,38.583314,0</coordinates>
7. </Point>
8. </Placemark>
9. </kml>
Ways to Create a KML File
• 1) Use Google Earth’s placemark creator.
• 2) Use a plain text editor such as Notepad
or an XML editor.
• Output data from a database in the correct
format. Later, we show how to do this with
an Access database and an XSL
transform.
Creating a Placemark
• Open up Google Earth.
• Click on yellow pushpin icon.
• Cursor over yellow box until cursor turns
into a pointing finger. Now move the box
where you want to put the placemark.
• Fill in a description. Click “OK.”
• Look over at sidebar on left; you should
see a label with whatever you called your
placemark.
Creating a Placemark (cont.)
• Click on the link on the left to go to the
placemark.
• Right click and go to “Properties.”
• Click on icon in upper right corner of box
to select a different icon.
Creating a Placemark (cont.)
Experiment with changing the following:
– Shape
– Color of placemark
– Scale
– Opacity
– Color, Scale and Opacity of Label
– View
– Altitude
Examine the KML
• After you’ve changed the settings, close
out of the placemark by clicking “OK.”
• Now find your file over on the left, right
click, select “Copy” and paste it into a
Notepad file.
• You will see the KML for the placemark
you just created.
KML Placemark (Page 1)
<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://earth.google.com/kml/2.2">
<Document>
<name>KmlFile</name>
<Style id="sh_ylw-pushpin1">
<IconStyle>
<scale>1.3</scale>
<Icon>
<href>http://maps.google.com/mapfiles/kml/pushpin/ylw-pushpin.png</href>
</Icon>
<hotSpot x="20" y="2" xunits="pixels" yunits="pixels"/>
</IconStyle>
</Style>
<StyleMap id="msn_ylw-pushpin0">
<Pair>
<key>normal</key>
<styleUrl>#sn_ylw-pushpin2</styleUrl>
</Pair>
KML Placemark (Page 2)
<Pair>
<key>highlight</key>
<styleUrl>#sh_ylw-pushpin1</styleUrl>
</Pair>
</StyleMap>
<Style id="sn_ylw-pushpin2">
<IconStyle>
<scale>1.1</scale>
<Icon>
<href>http://maps.google.com/mapfiles/kml/pushpin/ylw-pushpin.png</href>
</Icon>
<hotSpot x="20" y="2" xunits="pixels" yunits="pixels"/>
</IconStyle>
</Style>
<Placemark>
<name>Test Placemark One</name>
<description>Here is where test placemark one is located.</description>
KML Placemark (Page 3)
<LookAt>
<longitude>26.41145107108635</longitude>
<latitude>12.13590310050818</latitude>
<altitude>0</altitude>
<range>7891159.275852153</range>
<tilt>1.397977576698283e-014</tilt>
<heading>11.99119024368262</heading>
</LookAt>
<styleUrl>#msn_ylw-pushpin0</styleUrl>
<Point>
<coordinates>26.41145107108635,12.13590310050818,0</coordinates>
</Point>
</Placemark>
</Document>
</kml>
Changing an Access Database to XML
• Pick fields from the Access database to include in your
placemarks.
• Rename fields if they have spaces and characters such
as underscores (that don’t translate well to XML).
• Create and save a query using those fields.
• Export that query to a XML file, by going to the “External
Data” tab, then going to the “Export” tab, and going to
“More,” then selecting “XML File.”
• Notice that each record becomes an element
encompassed by tags bearing the name of the query.
• This above has just been to show you how to change the
data to XML. To create KML you’ll need an XSL
stylesheet.
XSL
• XSL stands for eXtensible Style
Language.
• XSL gives instructions for how data should
be displayed.
• Since KML is a subset of XML, we can use
XSL to transform KML to look the way we
want.
Using XSL with Access
• As you output the Access records to XML,
you can transform them by selecting an
XSL stylesheet.
• You can use this to:
– Choose elements
– Make decisions about elements based on
values
– Embed HTML to structure the data the way
you wish
– Automatically create placemarks
formatted the way you like.
Steps to Creating an XSL Transform
Include information on the XML version and encoding:
<?xml version="1.0" encoding="ISO-8859-1"?>
Call the xml namespace for xsl transforms:
<xsl:stylesheet xmlns:xsl=”http://www.w3.org/1999/XSL/Transform” version="1.0">
Say go to the root element:
<xsl:template match="/">
Indicate the version of kml that will be used:
<kml xmlns="http://earth.google.com/kml/2.2">
Put in document and name tags:
<Document>
<name>KmlFile</name>
Steps to Creating an XSL File (cont.)
<Style id="sn_ylw-pushpin">
<IconStyle>
<scale>1.1</scale>
<Icon>
<href>http://maps.google.com/mapfiles/kml/pushpin/ylw-pushpin.png</href>
</Icon>
<hotSpot x="20" y="2" xunits="pixels" yunits="pixels"/>
</IconStyle>
</Style>
<Style id="sh_ylw-pushpin">
<IconStyle>
<scale>1.3</scale>
<Icon>
<href>http://maps.google.com/mapfiles/kml/pushpin/ylw-pushpin.png</href>
</Icon>
<hotSpot x="20" y="2" xunits="pixels" yunits="pixels"/>
</IconStyle>
</Style>
Add formatting for the
pushpin icon. You can
copy and paste from
creating one by clicking
on the yellow icon and
reformatting it the way
you like.
Steps to Creating an XSL File (cont.)
<StyleMap id="msn_ylw-pushpin">
<Pair>
<key>normal</key>
<styleUrl>#sn_ylw-pushpin</styleUrl>
</Pair>
<Pair>
<key>highlight</key>
<styleUrl>#sh_ylw-pushpin</styleUrl>
</Pair>
</StyleMap>
Steps to Creating an XSL File (cont.)
Next, we will set out a statement that will select every data
record. Notice that here the exported KML file was built
from a query called “ExportQuery.”
<xsl:for-each select="dataroot/ExportQuery">
Then we give instructions on how to structure the
placemarks. For the name element, we select each value
of “Organization”.
<Placemark>
<name><xsl:value-of select="Organization"/></name>
Steps to Creating an XSL File (cont.)
Then we start the description tags. The xsl:value-of tag
tells to select the value of “Community.” Notice how we use
CDATA to create breaks.
<description>
<![CDATA[<br/>]]>
<xsl:value-of select="Community"/>
<![CDATA[<br/>]]>
Steps to Creating an XSL File (cont.)
<xsl:choose>
<xsl:when test="Town=DistrictState">
<xsl:value-of select="Town"/>
<![CDATA[ ,]]>
<xsl:value-of select="Country"/>
</xsl:when>
<xsl:otherwise>
<xsl:value-of select="Town"/>
<![CDATA[ ,]]>
<xsl:value-of select="DistrictState"/>
<![CDATA[ ,]]>
<xsl:value-of select="Country"/>
</xsl:otherwise>
</xsl:choose>
<![CDATA[<br/>]]>
<xsl:value-of select="Email"/>
</description>
What is going on here?
Steps to Creating an XSL File (cont.)
Below, we’ve asked the program to create placemarks circling the equator. These can
then be moved by hand into appropriate positions. Another, more exact, way to position
placemarks is to merge your Access file with latitude and longitude positions for places,
towns, and cities. There are free and paid sources available for latitude and longitude.
<Point>
<coordinates><xsl:number value="5 * position()"/>,0,5</coordinates>
</Point>
</Placemark>
</xsl:for-each>
</Document>
</kml>
</xsl:template>
</xsl:stylesheet>
After you’ve completed your xsl stylesheet, save it in Notepad with a .xsl extension.
Using an XSL Transform
To export your Access data to KML in Microsoft Access 2007 by using an XSL
transform, carry out the following steps:
1) Select table or query to export;
2) Click “External Data” tab;
3) Under Export, click “More” to show more export options, then “XML File”;
4) Browse to find the location you want to export the data to (being sure that it
will be saved as an XML file), click “OK”;
5) Be sure that the “Data” box is checked;
6) Click “More Options” and then click “Transforms.”
7) Click “Add” and find the .xsl file where you stored the code to transform your
data into XML. Click “OK.”
8) Be sure that “Export Data” is checked and under “Records to Export”, the “All
Records” radio button is selected.
9) Click “OK” to transform the data set to XML.
Creating a KML file
The file you just created will be output as an
XML file. You will need to change it to a
KML file by:
•Finding the file (using Windows Explorer)
and selecting it.
•Right clicking and renaming it as a .kml file.
Open the file in Google Earth
• Be sure that Google Earth is installed on
your computer.
• Select the KML file you created.
• Right click and select “Open with” and
“Google Earth.”
• Your placemarks should appear.
• This file can be posted on a web site and
downloaded so that others can make use
of the KML file you’ve created.
Creating Different Placemark Styles and Assigning
Them Based on an Attribute
• Often there is a need to create different types of
placemarks to differentiate between types of
organizations, places, etc.
• This can be done using an xsl:choose statement
in combination with xsl:when test statements.
• An example of an xsl spreadsheet that was used
to create blue ranger station icons (that look
similar to schoolhouses) to represent high
schools and red ranger station icons to
represent colleges is shown below.
<?xml version="1.0" encoding="ISO-8859-1"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
version="1.0">
<xsl:template match="/">
<!--This version has schoolhouses for placemarks.-->
<kml xmlns="http://earth.google.com/kml/2.2">
<Document>
<!--Each organization in the file is tagged as "ExportQuery" so the line
below selects each one-->
<xsl:for-each select="dataroot/ExportQuery">
<name>STAND</name>
<!--This begins the description of the red ranger station icon.-->
<Style id="sn_ranger_station">
<IconStyle>
<color>ffff5500</color>
<scale>1.2</scale>
<Icon>
<href>http://maps.google.com/mapfiles/kml/shapes/ranger_station.png</href>
</Icon>
<hotSpot x="0.5" y="0" xunits="fraction" yunits="fraction"/>
</IconStyle>
<ListStyle>
</ListStyle>
</Style>
<!--There is a pair of icons. Which one shows depends on whether the
icon is moused over or not.-->
<StyleMap id="msn_ranger_station">
<Pair>
<key>normal</key>
<styleUrl>#sn_ranger_station</styleUrl>
</Pair>
<Pair>
<key>highlight</key>
<styleUrl>#sh_ranger_station</styleUrl>
</Pair>
</StyleMap>
<Style id="sh_ranger_station">
<IconStyle>
<color>ffff5500</color>
<scale>1.4</scale>
<Icon>
<href>http://maps.google.com/mapfiles/kml/shapes/ranger_station.p
ng</href>
</Icon>
<hotSpot x="0.5" y="0" xunits="fraction"
yunits="fraction"/>
</IconStyle>
<ListStyle>
</ListStyle>
</Style>
<!--This begins the description of the blue ranger station icon.-->
<StyleMap id="msn_ranger_station_copy1">
<Pair>
<key>normal</key>
<styleUrl>#sn_ranger_station_copy1</styleUrl>
</Pair>
<Pair>
<key>highlight</key>
<styleUrl>#sh_ranger_station_copy1</styleUrl>
</Pair>
</StyleMap>
<Style id="sh_ranger_station_copy1">
<IconStyle>
<color>ff0000ff</color>
<scale>1.4</scale>
<Icon>
<href>http://maps.google.com/mapfiles/kml/shapes/ranger_stat
ion.png</href>
</Icon>
<hotSpot x="0.5" y="0" xunits="fraction"
yunits="fraction"/>
</IconStyle>
<ListStyle>
</ListStyle>
</Style>
<Style id="sn_ranger_station_copy1">
<IconStyle>
<color>ff0000ff</color>
<scale>1.2</scale>
<Icon>
<href>http://maps.google.com/mapfiles/kml/shapes/ranger_stat
ion.png</href>
</Icon>
<hotSpot x="0.5" y="0" xunits="fraction"
yunits="fraction"/>
</IconStyle>
<ListStyle>
</ListStyle>
</Style>
<!--The choose statement lets you apply different styles of placemark
design to different classifications of data.-->
<!--In this example,we differentiate between college and high school
organizations.-->
<xsl:choose>
<xsl:when test="Division='HighSchool'">
<Placemark>
<name>
<xsl:value-of select="School"/>
</name>
<!--The tag below tells which icon style above to use.-->
<styleUrl>#sn_ranger_station</styleUrl>
<description>
<![CDATA[<br/>]]>
<xsl:value-of select="City"/>
<![CDATA[,]]>
<xsl:value-of select="State"/>
<![CDATA[<br/>]]>
<xsl:value-of select="Zip"/>
<![CDATA[<br/>]]>
<xsl:value-of select="CONTACTNAME"/>
<![CDATA[<br/>]]>
<xsl:value-of select="CONTACTEMAIL"/>
</description>
<Point>
<coordinates><xsl:value-of select="Long"/>,<xsl:value-of select="Lat"/>,0</coordinates>
</Point>
</Placemark>
</xsl:when>
<xsl:when test="Division='College'">
<Placemark>
<name><xsl:value-of select="School"/></name>
<styleUrl>#sn_ranger_station_copy1</styleUrl>
<description>
<![CDATA[<br/>]]>
<xsl:value-of select="City"/>
<![CDATA[,]]>
<xsl:value-of select="State"/>
<![CDATA[<br/>]]>
<xsl:value-of select="Zip"/>
<![CDATA[<br/>]]>
<xsl:value-of select="CONTACTNAME"/>
<![CDATA[<br/>]]>
<xsl:value-of select="CONTACTEMAIL"/>
</description>
<Point>
<coordinates><xsl:value-of select="Long"/>,<xsl:value-of
select="Lat"/>,0</coordinates>
</Point>
</Placemark>
</xsl:when>
</xsl:choose>
</xsl:for-each>
</Document>
</kml>
</xsl:template>
</xsl:stylesheet>
Conclusion
• There are many ways to use Google Earth and
Google maps to portray information easily.
• We are just beginning to see the ways that this
application will be able to more easily convey
information.
• For more information on Google Earth and KML,
go to
http://earth.google.com/userguide/v4/tutorials/in
dex.html and
http://code.google.com/apis/kml/documentation/
kml_tut.html
Thank you!
Please contact me at:
Betsy Page Sigman
McDonough School of Business
Georgetown University
412 Old North
Washington, D.C. 20057
bps@georgetown.edu