Application of Virtual Globes in Education

Home , Digital Earth, Satellite imagery, Virtual globe, Web mapping

Geography Compass 2/6 (2008): 1995–2010, 10.1111/j.1749-8198.2008.00165.x

Application of Virtual Globes in Education Rahul Rakshit1* and Yelena Ogneva-Himmelberger2* 1Graduate School of Geography, Clark University 2Department of International Development, Community, and Environment, Clark University

Abstract The advent of virtual globes and online mapping has generated interest in spatial representations of data among many non-geographic communities, including educators and researchers who have very little to no expertise in geospatial technologies. In this article, we give a state-of-the-art survey of existing virtual globes and review the existing teaching applications related to them. We focus on the four most popular virtual globes (Google Earth; NASA World Wind; Microsoft Virtual Earth Earth; and Skyline Globe), illustrating their various applications and comparing their capabilities, with a particular emphasis on educational aspects. We also explain the distinction between the virtual globes and various online mapping applications, such as Google Maps mash-ups.

Introduction The introduction of virtual globes has led to great interest in spatial representation of data among many educators and researchers who had very little to no expertise in geospatial technologies. In fact, these communities are now actively engaged in adding geographic content to the virtual globes in the form of user-created files. Earlier, the display of satellite images and aerial photos, the animated flyovers, and three-dimensional display of the landscape were restricted to those who had access to and expertise in geographic information system (GIS) software and expensive datasets. Today, with the help of virtual globes, any computer literate person can do all these tasks with relative ease (Goodchild 2007). Thus, with minimal technical ability and a few mouse clicks, virtual globes can bring the varied geography of earth into one’s computer. The associated animations and overlays can be used to visualize hurricanes, wildfires, floods, dust storms, real-time stream gauges, and many other types of data which can be overlaid with satellite imagery (Patton and Hinkley 2006). Since the release of Google Earth in 2005, virtual globes have become one of the hottest topics within the professional geographic community

– several conferences organized separate sessions on this topic (Association of American Geographers and American Geophysical Union meetings; ESRI [Earth System Resources, Inc.] User Conference; International Symposium on Digital Earth). In addition, a conference devoted solely to virtual globes was held in Colorado in 2006 (earthSLOT 2008). Virtual globes provide a lot of new avenues for spatial education both for teachers and students. This review explores the use of virtual globes as an educational tool in geography. We aim to give a state-of-the-art survey of virtual globes and a review of the existing teaching applications related to them. All of our tutorials concern visualization of spatial data and patterns, but none of them require GIS software. We also address the confusion between virtual globes and user-created online maps, and talk about the limitations and issues related to virtual globes. This article focuses on the four most popular virtual globes: Google Earth, NASA World Wind, Microsoft Virtual Earth, and one of the most recent additions to the virtual globes scene, Skyline Globe. In an effort to increase the use of geospatial technology in the classroom, we also provide a list of Internet resources that aid in using virtual globes as a tool in education.

What Is a Virtual Globe? Virtual globes are similar to desk globes but they have the additional capability of simultaneous representation of many different thematic views of the surface of the earth. They show spatial data at multiple scales and in multiple ways, including photos and videos (World Wind Central 2008). The user can seamlessly zoom into the data, rotate the view, and tilt the image to see the terrain in three dimensions. Virtual globes display satellite imagery at various resolutions, aerial photos, topographic maps, elevation data, along with GIS layers like roads, administrative boundaries, points of interests, and place names overlaid on each other using a Web interface. The entire planet is covered, with around one-third of all land depicted at such high resolution that individual trees, cars, and the homes of 3 billion people, can be seen (The Economist 2007). Virtual globes are very helpful in finding a visual relation or a spatial pattern (Butler 2006). For example, if we superimpose a layer of earthquake activity with that of the population, we can see how many people live in earthquake zones and are likely to be affected in the case of an earthquake. This example demonstrates how virtual globes can be used as a disaster prevention and response evaluation tool. Virtual globes also act as an integrating medium to various Web services, as users can collaboratively view, share, and publish their own data for a location. For example, users can attach geotagged photos (photos with spatial coordinates embedded into them), videos, location points (called placemarks) or link Wikipedia articles about certain geographical locations

© 2008 The Authors Geography Compass 2/6 (2008): 1995–2010, 10.1111/j.1749-8198.2008.00165.x Journal Compilation © 2008 Blackwell Publishing Ltd Application of virtual globes in education 1997 using geotags. It requires two main components: the virtual globe software package and an Internet connection. The installed program works at the local (host) computer and the images (most of them not in real time) are streamed over the Internet to this host computer. These image data sets are very large (with resolution less than 1 m in many places); therefore, a fast broadband Internet connection and a computer with a fast processor are absolutely essential (Kerski 2006). Most of the virtual globes are available as a free download but some have high functionality (‘professional’) versions for a steep price. There are more than 30 virtual globes available on the Internet but for this review we chose four most popular ones: Google Earth, NASA World Wind, Microsoft Virtual Earth, and Skyline Globe, due to the availability of the data, ease of use, and advanced functionalities in them. While these virtual globes have many features in common, each of them has some unique characteristics and capabilities which we will review. Google Earth is the most popular globe application currently available. It is a free but closed-source application; thus, users cannot modify the software as per their specific needs. It is available in three versions: Google Earth (free), Google Earth Plus (US$20) and Google Earth Pro (US$400). Google Earth is aimed at the general public, primarily as a search and browse tool, but has attracted a large community of people, including scientists, who have used the application for a very wide range of purposes, primarily because of the ease of visualizing data through KML (Keyhole Markup Language). KML is a simple, open source language that is sup- ported by many virtual globes and is therefore already becoming a de facto standard. KML’s unique strength is that geometry, styling, display behavior, and feature attribute information are all contained in a single file that can be compressed using standard zipping technologies (Blower et al. 2007). The user can download KML that others have created, load them into Google Earth, and explore. NASA World Wind is a free, open-source cross-platform (i.e., based on OpenGL and Java), application that is part of NASA’s Learning Technol- ogies program. It was developed specifically as an educational and research tool to explore earth and it provides access to a wide range of NASA satellite imagery. Data can be imported through servers, Open Geospatial Consortium Web Services, and there is limited support for KML. World Wind’s focus is toward scientific users, so it has a more specialized community than that of Google Earth. World Wind’s functionality can be enhanced by using one of many add-ons (small extensions) and plug-ins that are created by users. Microsoft Virtual Earth is one of the latest big entrants in the virtual globes domain. It is also a free application primarily focused on providing geographical services and visualization tools to businesses and to the government. It includes Application Program Interfaces (APIs) to allow organizations to build their own applications that integrate Virtual Earth

Fig. 1. Coors field in Denver, CO, showing the high-resolution imagery available in MS Virtual Earth. Fig. 1A shows the high-resolution vertical image and Fig. 1B–E show oblique very high- resolution images from four different angles. imagery, features, and functionality. It is written in NET Framework and provides limited support for KML. It is a closed application like Google Earth, so the users can not alter it in any way. Virtual Earth provides the highest-resolution images called Bird’s Eye as compared to Google Earth and NASA World Wind (Figure 1). These images have a vertical view and

Fig. 2. Live traffic webcam in Washington, DC, available in Skyline Globe. four side views – from the north, east, south, and west (Google Earth Blog 2007a). Its two-dimensional version can be accessed online, and the three-dimensional version can be downloaded for free from Internet. Skyline Globe is another recent addition to the virtual globes scene. It was created by Skyline Software Systems Inc. and is available in two versions, basic (free) and pro (US$500). The basic version, like other virtual globes, includes high-resolution imagery, flying over the landscape, three-dimensional terrain and buildings, driving directions, and weather data. It can also import files in GIS format, other images, and KML files. In addition, it provides many unique features, such as census data layers, live feed from traffic video cameras, real-time global positioning system (GPS) tracking, etc. (Figure 2). It also has some analytical tools for measuring height difference, area and for generating contour lines. The pro version includes more GIS-like functions, such as the display of three-dimensional dynamic objects, tools for definition of line of sight and best path and viewshed analysis. Like NASA World Wind, it has an open API that allows anyone to create new tools and features.

Data Available in Virtual Globes Google Earth uses aerial photos and QuickBird satellite images (less than 1 m resolution) for some areas, Landsat imagery for other areas, and Shuttle Radar Topography Mission (SRTM) elevation data for terrain visualization.

Fig. 3. Mapping Server available in NASA World Wind.

Because the data come from different sources and the coverage is not uniform, some areas of the globe appear crisp all the way down to street level, while other areas are blurry from a great distance. In Google Earth, no imagery is viewed in real time. According to Google, all of the information that is seen is less than 3 years old and is continuously updated (Google Earth Groups 2007). The internal coordinate system of Google Earth is geographic coordinates (latitude/longitude) on the World Geodetic System of 1984 datum. Elevation data is of 10-m resolution for much of the United States. NASA World Wind uses a variety of data sets to provide images to the user. During the initial display, low-resolution (500 m) Blue Marble data sets are seen. As the user zooms into certain areas, additional high- resolution data is downloaded from the NASA servers including: US Geological Survey aerial photos (sub-meter resolution), Landsat imagery (30-m resolution), SRTM terrain data (30-m resolution), and topographic maps. The animated data layers include Scientific Visualization Studio and rapid-fire MODIS (Moderate-resolution Imaging Spectroradiometer). All images and movies created with World Wind using Blue Marble, Landsat, or US Geological Survey public domain data can be freely modified, re-distributed, and used on Web sites, even for commercial purposes (Figure 3).

Microsoft Virtual Globe’s high-resolution images are only available for the United States and some parts of Western Europe. These data are supplied by 20 different providers, including private and governmental agencies (Live Search Maps 2007). For some parts of the United States, the program has bird’s eye view images which are oblique aerial photos with very high resolution. Virtual Earth allows World Wind to access their high-resolution data for non-commercial purposes by using a plug-in (World Wind Central 2007).

Applications of Virtual Globes in Education Virtual globes have opened a new era in spatial representation of information and have changed the way we perceive our planet. They are becoming a valuable tool for teaching geography, spatial concepts, and for fostering spatial thinking. Ability to think spatially is named as one of the most critical skills for people living in the 21 century (National Research Council 2006). Learning geography involves using maps and atlases with a worldwide to local perspective. Virtual globes bring information from the globe, map, textbook, and Internet together in one application. As it is a visual medium, the students easily embrace the facts and figures and are very enthusiastic about using these tools (Lund and Macklin 2007). The interfaces of the virtual globes are designed in such a way that the users start using the features intuitively without any formal training. Virtual globes can aid teaching in various capacities. They can be used to investigate spatial phenomena like the folds of an anticline, or the forms of a river delta and topography of alluvial floodplains, to investigate a destination and roads that students are traveling on a field trip, the location of a news story, or the route of a historic or present-day explorer. Students can use the tool for inquiry-driven, problem-based, exploratory learning. Many educators worldwide have already embraced these technological inventions and are finding creative ways to incorporate them into their classes at all educational levels. Below, we describe some of the features of virtual globes that are particularly valuable for educational uses:

• Virtual globes can take the place of a conventional globe. Students can create their own placemarks, measure the distance between two points, draw lines, outline areas (polygons), and fly over the globe to any location. Virtual globes show cities, places of interest, international and administrative boundaries, roads, etc. overlaid over satellite imagery, thus providing a fun setting for students to learn geography. • Virtual globes also can play the role of an encyclopedia. Students can collect information about a place from Wikipedia and other user-created layers (photos, videos, and text) imbedded into Google Earth. However, because there is no formal control over the quality of the information

in Wikipedia, users must be aware that the information may not be accurate and crosscheck the content. • Virtual globes allow downloading various data sets and statistics. For example, using Web mapping server browser in World Wind, one can download images, statistics, and graphics on agriculture, forest fires and their impact, ozone measurements, cryosphere, population density, earthquake activity, hydrosphere, snow cover, volcano activity, plate boundaries, elevation and bathymetry, temperature, relative humidity, rainfall, snowfall, vegetation index, water quality, soil moisture and temperature, biomass, and many others. Most of these layers are also provided by NASA for the Google Earth users (http://svs.gsfc.nasa.gov/documents/ available.html) in the form of scientific visualization studio. Therefore, the user can just provide the coordinates of the place and get all the data from one source. • Virtual globes provide medium for sharing spatial information globally with the users who do not have access to commercial GIS software. Data produced in GIS can be shown as a layer on virtual globes. Likewise, data created as placemarks, lines, and polygons in virtual globes can be exported to GIS software using free conversion tools. • Virtual globes can help in the decision-making process by evaluating alternatives in a geographical context. For example, if a student is given a choice to select between two sites for waste disposal, he or she can zoom to locations on virtual globes and verify if the sites are away from populated places and water sources or if they are on a sloping terrain (important consideration for a liquid waste disposal). • Virtual globes are great tools for learning about geographical variation and for visualization of dynamic events. Google Earth and NASA World Wind have recently added a ‘time’ dimension in order to observe changes in different phenomena like vegetation, temperature, snow cover, etc., over time. The time series ‘stamp’ enables students to create an animation of the data, thus enhancing their understanding of the phenomenon and its magnitude. • The ability to display (near) real-time data is very important asset of virtual globes. For example, Google Earth can automatically refresh the link to the data source at predefined intervals (via NetworkLink facility in KML), ensuring that the user always sees the latest information. Many operational centers maintain networks of observing systems that must be continuously monitored. Some examples of real-time display of data include traffic alerts, weather, disaster relief, pollution-level monitoring, etc. • Virtual globes facilitate search and preview of satellite imagery. Many users of satellite imagery use specialized programs or Web sites to find and buy satellite images. It is a fairly complex and time consuming task to locate the exact coverage area codes and to find and preview the achieved images. Google Earth has now the SPOT and Ikonos imagery coverage layers to preview and buy the images directly. The user has to zoom to his or

her desired location and can see the satellite image extents, their codes and can click to view the archived images available for different years. • Three virtual globes (Google Earth, Microsoft Virtual Earth, and Skyline Globe) have the capability to show three-dimensional buildings and structures (such as bridges). The three-dimensional display can provide a better understanding of urban environments. Three-dimensional models are created by users using SketchUp, a free three-dimensional modeling program. In August 2007, Hamburg (Germany) became the first city entirely shown in three dimensions in virtual globe, including textures such as facades of buildings. These three-dimensional models coupled with the three-dimensional representation of the terrain help in a new functionality in the virtual globes called ‘flight simulator’ where one can fly over the terrain with the perspective of the pilot. World Wind, on the other hand, is available in anaglyph three-dimensional mode, that is, it provides a stereoscopic effect, when viewed with special three-dimensional glasses consisting of a red lens for one eye and a cyan lens for the other. • Live GPS data can be integrated with virtual globes, thus providing invaluable tool for data collection in the field. Google Earth can accom- modate up to 2GB of data into is cache so if a user zooms into an area, the image for that area is downloaded into the computer so that one can use Google Earth for viewing a limited area without having any Internet access. This feature of Google Earth can be very helpful in doing field studies as placemarks can be placed directly into Google Earth in the field. World Wind, on the other hand, allows unlimited cache size and image downloads, so one can use it without an Internet access and the image availability will be limited only by the cache on the computer. Virtual Earth does not allow GPS support at this time.

Information about the educational uses of digital globes is available but scattered throughout various conference proceedings and numerous websites. In hopes of assisting the reader, in this article, we provide a list of the teaching resources that we found the most useful (see Appendix 1) with a short summary for each resource. The authors have had a very positive experience using virtual globes in teaching GIS and remote sensing courses. In particular, we found virtual globes very helpful for the interpretation of classification results and for accuracy assessment, or ‘virtual ground truthing’.

Comparison between Virtual Globes All four virtual globes have their own advantages. World Wind is more oriented toward educational and scientific community, whereas Google Earth, Virtual Earth, and Skyline Globe are commercial applications mainly used for searching places. Some images in World Wind are updated on a daily basis whereas its takes 2 years to update the images in the other

Table 1. Comparision of the functionalities of virtual globes.

NASA World Google Earth MS Virtual Skyline Globe Wind Earth

Cost Free Free (Basic) Free Free (Basic) $400 (Pro) $500/Year (Pro) Scientific Yes Yes, through No Yes visualizations NASA World Wind Add-ons and Yes No No Yes plug-ins Open source Yes No No Yes Downloading Yes No No No imagery Image cache Limited only by 2 GB No No local storage size Driving directions No Yes Yes Yes and local searches Points of Not many Yes Yes Yes interests Ease of use Not so intuitive Very easy Very easy Very easy interface Measuring No Yes No Yes distances Adding text, No Yes No Yes photographs, and videos KML Support Limited to third- Yes Yes Yes party software Importing Yes Yes, only in Plus No Yes shapefiles and Pro versions GPS Support Yes Yes No Yes Three-dimensional No Yes Yes Yes buildings

globes. Google Earth has the most versatile user applications as it has biggest user community. World Wind has a plethora of scientific layers to download. Out of the four globes, Virtual Earth lacks thematic layers other than standard roads and administrative boundaries, but it has the best quality and resolution images available. Skyline Globe has high-resolution images only for the United States but has a set of analytical tools that no other digital globes have. All four allow import of KML files. As World Wind and Skyline Globe are open source, they allow creation of plug-ins and add-ons; this feature is lacking in the other two globes. The following table compares the functionalities of the four virtual globes (Table 1).

Difference between Virtual Globes and Online Maps Due to the recent explosive growth in the number of tools for online mapping, there is some confusion about these tools and how different they are from each other. To clarify virtual globes and virtual maps, the authors have included a brief discussion to differentiate the two. Using Google Earth and Google Maps as examples seems most natural as they are most commonly confused. Google Maps is specifically designed for trip planning with driving directions and searching for points of interest, whereas Google Earth is designed for more data-intensive tasks like three- dimensional fly over and showcase of user created geographic data layers with integrated multimedia, etc. Therefore, the target audience for both products is different. According to Google, when compared to Google Maps ‘Google Earth provides a more powerful, interactive user experience and offers more tools for learning about a location’ (Google Earth 2008). Google Earth is downloadable stand-alone software which has to be installed on a computer, whereas Google maps can be opened in a Web browser. Both of them show similar spatial information, but in different ways. For example, both use satellite data as the base layer. Google Earth includes many layers like detailed administrative boundaries, three- dimensional buildings, weather data, satellite images, etc., and these layers can be switched on–off; these layers are unavailable in Google Maps. Google Earth provides true three-dimensional impression as it allows one to fly over places, rotate, and tilt the image. Google Maps has a ‘terrain’ layer which is based on a hill-shaded elevation map, but it still feels like a two-dimensional map. Google Maps also has ‘Street View’ layer which provides high-resolution panoramic street images for some urban areas that can be rotated 360 degrees. Google Maps actively promotes the commercial use of their API in the form of Google Map’s ‘mashups’, a Web application that combines data from more than one source into a single-integrated tool. There are numerous online sources (e.g. http://www.maplib.net) and books (Brown 2006) on how to create a Google map-like interface using your own data. Google Maps user community is huge (http://googlemapsmania.com) and hundreds of thousands of thematic mashups are currently available (Goodchild 2007).

Issues Concerning Virtual Globes

VIRTUAL GLOBES AND GIS By definition, GIS is a mapping system that uses computers to collect, maintain, store, manipulate, analyze, and display data (Bolstad 2005). All virtual globes provide storage, collection, and display of spatial data. Some of them also have basic analytical capabilities (measuring area and length, viewshed analysis) but the number of GIS-like tools is still very limited in

© 2008 The Authors Geography Compass 2/6 (2008): 1995–2010, 10.1111/j.1749-8198.2008.00165.x Journal Compilation © 2008 Blackwell Publishing Ltd 2006 Application of virtual globes in education comparison to analytical tools available in any GIS software. However, we believe that virtual globes have many other valuable attributes which secure them an important place in geographic education for years to come.

INCORRECT DEPICTION OF COUNTRY BOUNDARIES According to Google, ‘Google Earth demarcates its maps according to international standards, following the guidance of the US Federal Infor- mation Processing Standards Publication and the International Organization for Standardization (ISO) 3166 standards’ (Dholabhai 2007). However, there are some inaccuracies present. For example, Google Earth showed the Indian state of Arunachal Pradesh as being administered by China but claimed by India. The situation on the ground, however, is the reverse: most of it is controlled by India, though the Chinese lay a claim to it (Dholabhai 2007). A small town in remote southern Chile was shown to be in Argentina in Google Earth due to an error in the database Google is using (Google Earth Blog 2007b).

UNEVEN DATA COVERAGE The majority of high-resolution datasets, points of interests, and road layers for driving directions are available for the United States and Western European countries. World Wind and Virtual Earth do not have any high-resolution datasets except the United States and some European countries.

NOT EVERY COMPUTER CAN HANDLE IT The globes require a great deal of computational power, especially with respect to using the latest graphics display cards. Low-end computers that are more than 2 years old may not be compatible. Furthermore, a high- speed broadband Internet connection is needed to run these programs.

Conclusions Virtual globes have opened a new era in spatial data visualization and have been playing an important role in the ‘democratization’ of GIS (Good- child 2007). Users can experience planet Earth via virtual globes in ways not imaginable before. These tools have a very attractive interface and make learning geography fun. All these assets make virtual globes a potentially valuable tool for educators. However, issues that are common to tradi- tional cartography and GIS are also present in virtual globes (data quality, spatial errors, lack of metadata, etc.) As educators, we should use these shortcomings as ‘teachable’ moments and encourage our students to be critical and informed consumers of spatial data.

Short Biographies Rahul Rakshit is a graduate student in Geography at Clark University, MA, USA. He is presently pursuing a PhD on ‘Methods of Map Comparison’. He received his BS in Geology from Guru Ghasidas University, India, and MS in Applied Geology from Barkatullah University, India. He is the co-author (with Piyoosh Rautela: 2002, Current Science) of ‘GIS and Remote Sensing’ – based study of the reservoir – induced land-use/land-cover changes in the catchment of Tehri dam in Garhwal Himalaya, Uttaranchal (India). His interests lie in formulating the applications of virtual globes for non-GIS users. Previously, he has worked as a GIS analyst and a cartographer. Yelena Ogneva-Himmelberger is an Assistant Professor of Geographic Information Science in the Department of International Development, Community, and Environment at Clark University, Worcester, MA, USA. She teaches introductory and advanced courses in GIS and remote sensing. Her current research interests are in health applications of GIS, spatial statistics, environmental justice issues, land-use change and environmental degradation. She recently co-authored a paper ‘Diesel Particulate Matter, Lung Cancer and Asthma Incidences along Major Traffic Corridors in Massachusetts, USA: A GIS Analysis’ to be published in Health & Place in 2008. She is presently co-editing a book on ‘Environmental justice and sustainability in the Former Soviet Union’ to be published by MIT Press. Yelena holds an MA in Geography from Moscow State University and a PhD in Geography from Clark University.

Note * Correspondence address: Rahul Rakshit, Graduate School of Geography, Clark University, 950 Main Street, Worcester, MA 01610-1477, USA. E-mail: [email protected]. Or Yelena Ogneva- Himmelberger, Department of International Development, Community, and Environment, Clark University, 950 Main Street, Worcester, MA 01610-1477, USA. E-mail: [email protected].

References Blower, J., Gemmell, A., and Haines, K. (2007). Sharing and visualizing environmental data using virtual globes. Proceedings: All-Hand Meeting, UK. [online]. Retrieved on 30 March 2008 from http://www.nesc.ac.uk/talks/ahm2007/792.ppt Bolstad, P. (2005). GIS fundamentals. White Bear Lake, MN: Eider Press. Brown, M. C. (2006). Hacking Google Maps and Google Earth. New York: Wiley. Butler, D. (2006). Virtual globes: the web-wide world. Nature 439, pp. 776–778. Dholabhai, N. (2007). Arunachal is Chinese on Google earth. The Telegraph Online Edition, 26 October 2007. [online]. Retrieved on 30 March 2008 from http://www.telegraphindia.com/ 1071026/asp/nation/story_8474517.asp earthSLOT. (2008). First Annual Virtual Globe Scientific Users Conference, 10–12 July 2006, Boulder, Colorado. [online]. Retrieved on 30 March 2008 from http://www.earthslot.org/ vgconference/agenda.php Goodchild, M. F. (2007). Citizens as sensors: the world of volunteered geography. GeoJournal 69 (4), pp. 211–221.

Google Earth. (2008). How is Google Earth different from Google Maps [online]. Retrieved on 1 June 2008 from http://earth.google.com/support/bin/answer.py?hl=en&answer=20707 Google Earth Blog. (2007a). Virtual earth 3D comparisons with Google Earth [online]. Retrieved on 30 March 2008 from http://www.gearthblog.com/blog/archives/2007/05/virtual_earth_ 3d_com_1.html ——. (2007b). More on Chile border problem. [online]. Retrieved on 8 March 2008 from http:// www.gearthblog.com/blog/archives/2007/04/more_on_chile_border.html Google Earth Groups. (2007). Google Earth help: age and clarity of imagery. Retrieved on 10 March 2008 from http://groups.google.com/group/earthdata/browse_thread/thread/ 49860044a621a6aa?tvc=2 Kerski, J. (2006). Exploring the world in 3D with Google Earth: could it be that the world is finally discovering how useful geography really is? [online]. Retrieved on 30 March 2008 from http:// education.usgs.gov/common/lessons/google_earth_in_education.pdf Live Search Maps. (2007). Locational usage notes. [online]. Retrieved on 30 March 2008 from http://maps.live.com/Help/en-us/CodeOfConduct.htm Lund, J., and Macklin, S. (2007). ArcGIS and Google Earth: rules of engagement. San Diego, CA: ESRI Education Users Conference, June 2007. [online]. Retrieved on 30 March 2008 from http://gis.esri.com/library/userconf/educ07/educ/papers/pap_1546.pdf National Research Council. (2006). Learning to think spatially. Washington, DC: National Academies Press. Patton, S. C., and Hinkley, E. (2006). Google Earth: Drape Your Geospatial Data . . . Proceedings: RS-2006 New Remote Sensing Technologies for Resource Managers, Salt Lake City, Utah. The Economist. (2007). The world in your desktop. The Economist Online Edition. [online]. Retrieved on 30 March 2008 from http://www.economist.com/science/tq/displaystory. cfm?story_id=9719045 World Wind Central. (2007). Virtual earth add-on for World Wind. [online]. Retrieved on 30 December 2007 from http://www.worldwindcentral.com/wiki/Add-on:Virtual_Earth,Retrieved on 12 March 2008 ——. (2008). World Wind. [online]. Retrieved on 30 March 2008 from http://www. worldwindcentral.com/wiki/World_Wind

Appendix virtual globes: general resources •Google Earth download: http://earth.google.com earth.google.com • NASA World Wind download: http://worldwind.arc.nasa.gov/download.html • Microsoft Virtual Earth download: http://www.microsoft.com/virtualearth/ • Skyline Globe download: http://www.skylineglobe.com/SkylineGlobe/ corporate/home/index.aspx • Skyline Globe Frequently Asked Questions: http://www.skylineglobe.com/ SkylineGlobe/corporate/home/faqs.aspx • Google Earth Lat-long (http://google-latlong.blogspot.com): news and notes by the Google Earth and Maps team. This is the official blog from Google and provides news and links on latest usage of Google Earth and Google Maps. • Using Google Earth (http://googleearthuser.blogspot.com): provides many tips and tricks on using Google Earth. • Ogle Earth (http://www.ogleearth.com): provides news about virtual globes, with a special focus on Google Earth. This site includes a lot of technical details.

• GE Graph (http://www.sgrillo.net/googleearth/gegraph.htm): a free graphical application for Google Earth. A user can create graphical representation of features on top of Google Earth and it is fantastic for demonstrating spatial patterns. A user can draw a line, point, or polygon feature and can then attach some data like population/pollution with that feature to create a three-dimensional graph. Users can also bring data from txt or excel files into the application to create graphs. A user can set graph values, colors, scales, and labels. • GE Path (http://www.sgrillo.net/googleearth/gepath.htm): a free application which allows you draw paths and save them as KML files. The data can also be typed into the application or pasted/exported to the clipboard. Files generated by Google Earth–Path are exported to Google Earth. This application also calculates distances, bearing and area. Hence, if a user wants to draw a boundary of his or her study area without using any GIS software, Google Earth–Path is the solution. It can also be useful to create grids for field work. • Google Earth Blog (http://www.gearthblog.com): this blog is the most comprehensible resource on applications of Google Earth in the Inter- net. It is dedicated to sharing the news, interesting sights, technology, and happenings for Google Earth. It has a lot of amazing and interesting Google Earth files and network links which a user can download right off the site.

VIRTUAL GLOBES: RESOURCES FOR EDUCATION • Juicy Geography (http://www.juicygeography.co.uk/blog): provides teaching ideas with Google Earth. The blog includes ideas for lessons, user guides, essential files, teaching tips, etc., for educators. • Google Earth Lessons (http://www.gelessons.com): this blog is one of the most useful resources for teachers to get lesson ideas using Google Earth. It contains tons to lesson ideas for the topics ranging from environment, conservation, geography, and history. • World Wind Education (http://www.worldwindcentral.com/wiki/education): is a source of information and ideas for using World Wind in education. It has various links on tips and ideas and resources on using World Wind for educational uses. • World Wind in Classroom (http://www.worldwindclassroom.com): provides neat ideas on using World Wind and other virtual globes as an interactive aid for lectures and powerpoints. • G Census (http://gecensus.stanford.edu/gcensus/index.html): this Web site shows the spatial representation of census data is for each state of United Stats to explore population density, median age, and male/ female ratio in each state at two levels of detail, one at the county level, and a higher-resolution level at the census block level which it converts into as a KML layer to open in the virtual globes. Thus, there is no

need to download the tabular data from census’s Web site and then connecting that data to spatial data in GIS software. • Batch Geocode (http://www.batchgeocode.com): provides easy geocoding of address’s list using files copied from txt files or excel to be opened directly on top of Google Earth as a point KML or back to excel with a lat-long field added. • Google Earth Educational Initiative: the Google Earth Education Initiative provides a free license for Google Earth Pro for educational institutions by sending an application to [email protected] Both World Wind (http://www.worldwindcentral.com/wiki/Education) and Google Earth (http://bbs.keyhole.com) have a strong user community that includes an ‘Education’ section where students and educators share their ideas and resources. Whereas students most often exchange placemarks, educators discuss problems encountered while trying to implement Google Earth in the classroom.