Using KML to Display Scientific Data in

GoogleEarthBy Jim Graham

May, 2008

1. How GoogleEarth Works2. Display Excel Data in GoogleEarth3. Creating KML Files for GoogleEarth

Contents

Section 1: How GoogleEarth Works

How GoogleEarth Works

Local ComputerWeb Server

Internet

GoogleEarth

KML Files

Satellite Images

Spreadsheet Files

Created by Denver-based company, Keyhole An application that runs on your computer GIS Services for various layers A system that you can add data to Commercially owned

GoogleEarth

Common file formats:◦ Word (*.doc)◦ PowerPoint (*.ppt)◦ Excel (*.xls)

File Formats

Shapefiles Coverages GeoTIFF Lots of others Is KML a GIS format?

GIS File Formats

Small Graphics Markup Language (SGML) HyperText Markup Language (HTML) Extensible Markup Language (XML)

Keyhole Markup Language (KML)

Based on XML Very simple, flexible format Can be create very complex files Not an industry standard (could change at

any time, only works in GoogleEarth) KML Documentation:

http://code.google.com/apis/kml/documentation/

Or search on ‘KML’ into Google

Keyhole Markup Language (KML)

Rasters (photos)◦ Satellite◦ Aerial

Vector Data◦ Points◦ Polylines/Paths◦ Polygons

GIS Data

Add Placemark Add Path to and from somewhere Add Polygon around your school Save As… KML files

Play with KML

KML is still very new Shapefiles are the most common GIS vector

format Converters are coming Shapefiles are much more limited than KML

files (i.e. it’s easy to go from Shapefile to KML, can be harder to go from KML to Shapefile)

Situation

When should data be in a local file vs. on a web server?

What are the possible futures for KML?

Discussion Points

Local ComputerWeb Server

Internet

Problem: Display spreadsheet data in GoogleEarth

Solution:◦ Use an Excel “Add-In” that converts data in

spreadsheets to a KML file◦ Open the KML file in GoogleEarth

Section 2: Displaying Excel Data in GoogleEarth

Actually Excel files that include “Macros” Hidden in your “Add-In” folder

Excel Add-Ins

1. Install WriteToKML Add-In to your system2. Make WriteToKML available to Excel3. Add a custom tool to Excel 4. Use the tool to save a KML file 5. Make more interesting descriptions

WriteToKML AddIn

Discussion point: What type of data would you collect to make this work?

Discussion Points

The WriteToKML Add-In is limited Does not support:

◦ polygons and paths◦ Graphics◦ Icons◦ Lots of other features of KML

http://earth.google.com/kml/index.html

Section 3: Creating KML Files

Simple text files without any formatting Write in NotePad (TextEdit on the Mac), not

MS-Word or other “word-processor”

Creating KML Files

1. Search on “KML” in Google2. Click on “KML Documentation

Introduction”3. Click on “KML Tutorial”4. Scroll down to light blue boxes5. Copy everything in the box into a new

NotePad file6. Save as “text.kml”

Getting Started

What is the approximate coordinate? What is the name? What is the description?

Drag KML file into GoogleEarth

Open GoogleEarth and Notepad Steps:

◦ Edit in NotePad◦ Save to a file on the desktop◦ Double click on the file◦ Click “Yes” to reload and view the file◦ Repeat

Change name, description

Writing KML Files

<?xml version="1.0" encoding="UTF-8"?><kml xmlns="http://earth.google.com/kml/2.2"> <Document> <Placemark> <name>Name of the Placemark</name> <description> Description appears in the balloon

</description> <Point> <coordinates>102.595626,14.996729</coordinates> </Point> </Placemark> </Document> </kml>

“Simple” KML File with 1 Point

Multiple points◦ Add “Document” tags”◦ Add another point, save, view

Some fun stuff- Photos, paths, etc.

KML “Developer’s Guide” KML Reference

Where to go from here

How would you use this in your classroom? What types of data would kids find cool to

put into GoogleEarth?

Discussion Points

Web server/client architecture Spatial Data File format: KML Converting from Excel to KML How to edit KML files

What is it you just did?