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Recent developments in Internet GIS

Ming-Hsiang Tsou<
Ming-Hsiang Tsou
Department of Geography,
San Diego State University
San Diego
Email: mtsou@mail.sdsu.edu


THE YEAR 2005 is a very important year for the development of Internet GIS. Many significant changes have taken place in this year in terms of new technology, new services, new infrastructures, and new users. Even though it is only September now, and we still have three more months left, I am pretty sure that this year (2005) will be unforgettable in the history of Internet GIS. This paper will highlight three major changes happened in the development of Internet GIS in 2005 and discusses its future impacts in the next decade.

THE FIRST BIG CHANGE: GIS AWARENESS
The first big change comes from the GIS awareness in the general public. Two major events, the South Asia Tsunami and the Hurricane Katrina, started to wake up people how important the GIS is in order to protect our homes, our friends, and our own lives. GIS is a good teacher for us and it teaches us how to respect Nature and how to understand her actions. When viewing satellite imagery, categorizing land use data, or comparing the changes of land cover before/after the disasters, we are getting very important messages from Nature. These important messages can be received by hundreds of millions people almost immediately via Internet GIS. Many major satellite image companies (such as Digital Globe and Space Imaging) and GIS vendors (ESRI and Google) are generously offering free satellite images and GIS data/maps for the general public and the media. The general public can vividly see the changes of images caused by natural disasters and feel the devastating power of these events. Many media (TVs, newspapers) were copying these images from the Internet and then re-broadcast to hundreds of million viewers all over the world. Thank to the progress of Internet GIS technology and the World Wide Web, people can access many GIS data and maps in near real-time whenever they are available. People started understanding the power of geospatial technology because seeing is believing. I started to realize this big change of GIS awareness, when I watched the CNN news in September 2005 after the Hurricane Katrina. The director of Federal Emergency Management Agency (FEMA) in U.S. told the CNN reporters specifically that the FEMA rescue efforts are heavily relying on GIS technology. It is so sad to realize that after we lost hundreds of thousands human lives (in the Tsunami event) and billions of dollar's damages (in the Hurricane Katrina event).

These tragedies started to create the GIS awareness for our general pubic and everyone begins to understand that GIS is a vital technology for our society. Figure 1 shows a screen shot of the Google Earth Pro with the GIS data indicating the RedCross Shelter's location and capacity for the Hurricane Katrina relief.


Fig 1 The Google Earth Pro showing the RedCross Shelter location and capacity for Hurricane Katrina relief efforts (All materials Google Inc.)

THE SECOND BIG CHANGE: NEW COMPUTING TECHNOLOGIES FOR INTERNET GIS
The second big change in Internet GIS is the adoption of new technologies in the Internet GIS market, especially for the development of AJAX (Asynchronous JavaScript and XML) and image tiling techniques for Web-based 3D visualization.

Traditional Internet GIS applications and Web-based mapping tools always suffer from the slow response and the lack of high resolution images because of the limitation of image data sizes and the client/server communications. The two new technologies (AJAX and image tiling) can improve the performance and repose times of Internet GIS application significantly.

Strictly speaking, the two new technologies have been existing for a while long before Year 2005. However, the combination of the two technologies has not been seen until the early 2005. [maps.search.ch] and [maps.google.com] are the two early examples of Internet GIS applications which adopt both AJAX and Tiling techniques together. Amazon's [maps.a9.com] is also a good example of AJAX applications with a very interesting "Street Block View" function. Microsoft also has its own AJAX map application [virtualearth.msn.com].
v AJAX is not a single technique but a combination of multiple web techniques for creating fast response, interactive web applications. AJAX can send user's requests to the web server to retrieve only the data needed by the request. Therefore, the total amount of images or data interchanged between the client browser and web server will be reduced significantly. For example, if users need to zoom-in to a new map area in a Web map browser, the server will not need to reprocess the whole Map page content but only to re-send the smaller area of map requested by the user. By using Simple Object Access Protocol (SOAP), JavaScript, or similar XML-based web service protocols, AJAX applications users can have very responsive actions.

One unique advantage of AJAX is the key word "Asynchronous". According to the first AJAX paper (written by Jesse James Garrett - "An Ajax application eliminates the start-stop-start-stop nature of interaction on the Web by introducing an intermediary - an Ajax engine - between the user and the server. It seems like adding a layer to the application would make it less responsive, but the opposite is true. Instead of loading a webpage, at the start of the session, the browser loads an Ajax engine - written in JavaScript and usually tucked away in a hidden frame. This engine is responsible for both rendering the interface the user sees and communicating with the server on the user's behalf. The Ajax engine allows the user's interaction with the application to happen asynchronously - independent of communication with the server. So the user is never staring at a blank browser window and an hourglass icon, waiting around for the server to do something." (Cited from http://www.adaptivepath.com/publications/essays/archives/ 000385.php). Figure 2 illustrates the synchronous interaction pattern of a traditional web application compared with the asynchronous pattern of an Ajax application.


Fig 2 The synchronous interaction pattern of a traditional web application (top) compared with the asynchronous pattern of an Ajax application (bottom)


Fig 3 A Three-layer Tile-based Pyramidal Image Model

The second major technique used in the Internet GIS is the Image Tiling for Web-based 3D visualization. The introduction of tiled images is to improve the application performance by allowing the application to process an image region within a number of tiles without bringing the entire image into computer memory. Many early Web image applications have adopted this method for a while. In early 2005, several Internet GIS applications (such as Google Earth (http://earth.google.

com) and GeoFusion (http://www.geofusion.com/) started to improve the image tiling techniques for their 3D visualization tools and created an interactive, fast-performance virtual reality in a digital earth form. Users can overlay aerial photos, satellite images with digital elevation model (DEM) to visualize the 3D spatial information.

Figure 3 shows an example of image tiling technique. The large size image is first shrunk down to different resolutions for building multi-level image pyramid layers, and then each layer is further broken into smaller tiles in a separate file with a standard naming convention related to the specific tile position. The tiles are typically same size squares except for the right and bottom side, because the image width and height may not be exactly the integer multiples of the tile width and height. In order for fast retrieval of the necessary tiles upon request, the adjacent tiles in the same layer are normally named in sequential order. The entire tile-based pyramidal data are stored in a hierarchy, indexed format at the server-side database (Figure 3).


Fig 4 A Web mapping tool for high school teachers and students


Fig 5 NASA World Wind Application (An Open-Source Internet GIS example)

To represent the reality, users typically see only part of the image on the fly instead of the whole one. The adoption of tiling technique is to aid the presentation of very high resolution imagery and halts the unnecessary work on off-screen sections.

This prevents the memory overload, decreases processing and bandwidth requirements, and making it possible to move quickly from one section of the image to another.

By combining both the AJAX and image tiling technologies, the Internet GIS application developed in 2005 have much faster performance and interactivity comparing to the traditional Internet mapping or Web-based GIS tools. This is critical for the general public because more people will start to use Internet GIS because of these improvements.

THE THIRD BIG CHANGE: INTERNET GISERVICES USERS AND PROVIDERS
The third big change is the users of Internet GIServices and the service providers. According to a recent research from ComScore Network ((http://www.ebrandz.com/newsletter/ 2005/July/1july_31july_article1.htm), online map users are a huge market. Currently, Time Warner's [MapQuest.com] has estimated 43.7 million U.S. visitors in May 2005, the [Yahoo!Maps] has 20.2 million users, Google Map (maps.google.com) with 6.1 million and Microsoft's MSN MapPoint (mappoint.msn.com) has 4.68 million visitors, according to ComScore Networks. This is a huge market for online mapping services comparing to traditional GIS users. It is interesting to see the new online mapping providers, such as Google and Amozon to join the market of online mapping and provide more diversified geospatial information services.

One unique feature of Google online mapping services is that it provides an open API (application programming interface) for connecting to other Web applications. For example, programmers can get free API codes to overlay the Google maps and satellite images with their own applications, such as realtor markets, GPS tracking, or external business works. This open Google-Map API attracted more software developers and users for creating more useful web mapping services. After the successful story of the Google API, the Yahoo!Map and Microsoft are also releasing similar functions this year.

Another fast-growing domain is the wireless location-based services (LBS) on mobile devices, such as PDAs, PocketPCs, or mobile phones. Many GIS vendors and Internet GIServices providers started to focus on this market in 2005 and created many interesting applications, such as "Google Mobile Local Search" (http://mobile.google.com/loc_search.html). With the progress of wireless technology, including Wi-Fi, WiMAX, and 4G cellular phone systems, people can access on-line maps and Internet GIS from anywhere via portable devices. 2005 is a boost point for the new types of mobile GIS applications. In Year 2005, we also see more and more different types of Internet GIS applications for various users. Internet GIS and Web mapping have been applied in homeland security, disaster management, business market, transportation, city planning, and K-12 educations. Figure 4 is an example of Internet GIS (ESRI's ArcIMS) adopted in a high school biology course and the web maps were used by high school teachers and students for their field survey in San Diego Bay (http://geoinfo. sdsu.edu/hightech).

CONCLUSION
Along with the three big changes in both academic research and commercial markets of Internet GIS, the new pretty face of Internet GIS will attract more people to use it and it will transform the way people live, work, and behave. The general public will have different ways to collect, analyse, and distribute information - geographically. These changes in Internet GIS will provide a testimony for the first law of geography. According to Dr. Waldo Tobler (Emeritus Professor at UC-Santa Barbara, Geography Department), the first law of geography is "Everything is related to everything else, but near things are more related to each other." If we apply this law into the changes in Internet GIS, we can see that "Everything can be related to a spatial factor, and near things are more "sale-marketable" to potential users". (Yes, you will more likely to buy a ice-cream cone from your neighborhood store rather than a distant supermarket store ten miles away).

So, in the future, when you go to online shopping store, like Amazon.com, you might be able to virtually "walk" on the Broadway Street in Downtown San Diego and then click on a cozy bookstore located in the corner of your computer screen. Then you "enter" the virtual book store to buy an antique book published in 1922. Or you can physically walk on a street with your cellular phone beeping a $5 discount e-coupon for a coffee shop in the next street block (the cellular phone can detect your location by GPS and then advertises all e-coupon from the nearby stores within 100 meters).

I have one last note for the future development of Internet GIS. Although the private GIS vendors and software companies such as ESRI, Microsoft, Google, and Intergraph play an important role for the future Internet GIS development, the Open Source Software Society will also become a strong player in the technological advancement of Internet GIS. For example, the very popular NASA World Wind is an excellent Internet GIS application, which creates a virtual digital earth to display various scientific data and to overlay multiple NASA satellite images (Figure 5). Since it is an Open-Source Project developed by NASA. People can add various applications beyond the original functions of World Wind.

The pretty face of Internet GIS will be constantly changing. As a GIS professional and a faculty member at a university, I am very curious to see if we can discover a real killing application in Internet GIS. A really useful Internet GIS application can be used for everyone in everyday, just like watches or cellular phones. I hope that at the end of 2005, we might be able to see one or two Internet GIS applications emerged from the thousands of GIServices and become the ONE. Let's wait and see.

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