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Internet based GIS solutions

Andy C. Shaw
CADDScan Engineering, Inc.
9861 Broken Land Parkway, Suite 168 Columbia, MD 21046


As the computer and Internet technologies continue to improve, and cost of digital storage continues to lower, many major GIS providers are now offering Internet based GIS solutions. This technology allows users to access enterprise GIS using an ordinary World Wide Web (WWW) browser. Not only does it eliminate the need to maintain a desktop license for each GIS workstation, but, due to its OPEN nature, it also broadens the feasibility to integrate GIS with other devices for intuitive purposes. This presentation demonstrates the integration of GIS, GPS, wireless communication and Internet technologies to allow real-time map/data retrieval, dynamic foreground map display and real-time GIS data updating. Internet GIS connects the field crew directly with the remote GIS server. With this system, working with disconnected data sets is history, Internet Based GIS does everything dynamically.

Internet based GM
The key components of an Internet Based GIS are the Publishing Engine (PE), a WWW interface, an Internet Server, and a GIS database. PE is a server-based application with connections to both the Internet Server and the GIS database. When a user opens the GIS web page and requests a map or data through the Internet Server, PE receives the requests and communicates with the GIS database to produce the results, which are sent back to the user.



The results published by the PE can be either in vector, raster, or text format. Different providers support different types. Popular map image formats supported include JPEG, SVF and CGM.

Generally speaking, JPEG is more compact in size but has limited ability to carry embedded data to the browser. SVF and CGM, on the other hand, will display intelligent objects on the map and will allow more local viewing functions such as zoom, pan, rotate and fit view. Depending on the PE vendors, it is also possible to install controls or download plug-ins from the browser to thicken the client so it will perform more fimctionality.

Integrate Internet Based GIS with GPS and Wireless Device
Enterprise GIS can virtually be extended to any remote location by combining Internet GIS with GPS and wireless technologies. With GPS offering the location information, a user in the field can retrieve a map of the surrounding area. Retrieving and updating the database information for utility equipment, work order status, and data collection can be sent to a centralized database from multiple users in real time, eliminating database synchronization and ofice input efforts. GIS can then be integrated with enterprise IT subsystems such as equipment inventory, scheduling, invoice tracking and project management.

To achieve this, an ActiveX control is required on the client for the field computer to recognize the NEMA standard signals received from the GPS connected with the serial port. On the server, an Active Server Page (ASP) application is required to control the display of the browser as well as handle the communications between the browser and the Publishing Engine.

When a user opens the web page, an ASP application displays maps with GIS features published by the Internet GIS Server. According to the locational coordinates from the ActiveX GPS control, the browser displays the appropriate map. The ASP based application is also the middle tier object communicating the field browser with the Internet based GIS Publishing Engine. When a user selects an object, sends a query, or makes an update request, the ASP application sends the request to the Internet GIS Publishing Engine for processing and returns the database result back to the client. In order to achieve real-time mapping, a wireless modem is required on the field computer. As long as the user can connect to an Internet provider, the communication between the field computer and the corporate server will allow dynamic map display and GIS database access.

A schematic diagram on the following page illustrates all the components required to accomplish the real-time remote GIS.



Sample Projects
Four sample projects are selected to demonstrate Internet based GIS. They are:
  1. Howard County ( Maryland) Property GIS (GeoMedia WEB Map based)
  2. Maryland Property GIS – MdProperty View (MapObjects Internet Map Server)
  3. PEPCO Utility Online (ModelServer Discovery)
  4. Howard County (Maryland) Road Pavement Inventory (MapObjects, GPS, Wireless Modems)
Howard County Property GIS
Howard County maintains its GIS property data in an Intergraph MGE system. Over the years, Howard County has developed a comprehensive parcel vector dataset using Bentley Systems MicroStation. Using GeoMedia WEB Map, Howard County is publishing its MGE based GIS map and attributes on the Internet. This web application is used to facilitate the retrieval of the assessment data making use of a snapshot of the GIS database. Users can query for specific GIS data, build maps, and output reports from their web browser.

As an example, a user may query for a location by keying in an address. The textual results are displayed in the Query/Report frame and maps are displayed in the Map Frame at predefine zoom level with a highlight placed on the queried feature. Reports can be generated by selecting features on the Active CGM Map. Standard view control buttons (zoom in, zoom out, zoom window, pan in the map frame) are available from the browser to adjust the map view.



Maryland Property GIS – MdProperty online
A good example of using ESRI MapObjects technology to publish sizable GIS datasets on the Internet is MdProperty Online. The application demonstrates a convenient, user-friendly and perhaps the most affordable way to access current, reliable Maryland property data on the Internet. MdProperty View data, which is the most accurate and current database compiled by the Maryland Office of Planning, is used in conjunction with optimized database formats and queries. With any connection to the Internet, you can obtain property information by simple key-in criteria(s) such as: Owner Name, Address, Street Name, House Number, Map Number and Account ID.

Search results will be shown as a list of properties that match your criteria(s). Each property is linked to a property profile report containing detailed structure, taxes, and sales information. In addition to the ability to view a neighborhood sales report and property maps, you can also click on any property displayed on the screen for review. MdProperty Online is designed to locate the target property quickly and print the detailed information. It is a good example of allowing point and click technology on a map to obtain information about neighborhood properties.



Potomac Electric Power Companv (PEPCO) Utilitv Online
Potomac Electric Power Company (PEPCO) maintains its utility maps in MicroStation DGN files. Information for the devices is stored in an ORACLE database. Model Server Discovery is used to publish the GIS data from a Geographic project into JPEG, SVF or CGM format. A set of web pages is developed with JavaScript to allow user to publish any map grid in the service area. A Java viewing applet is used as a thick client to accomplish GIS-like functionality such as spatial queries, customized SQL queries, map display management, etc. This implementation enables remote offices to view desired utility maps and data associated with the objects on the map.



Howard Countv Road Pavement Inventorv
In connection with the Howard County Roadway Pavement Management project, CADDScan has developed an Internet GIS solution integrating GPS and wireless CDPD communication.

This solution demonstrates the use of GPS and wireless communication to access remote database and GIS servers in real-time. The map display on the field computer dynamically updates while the user is traveling. When GIS objects are queried, field users receive the most updated information directly from the corporate server. All the field users need is a browser and a small optional GPS interface ActiveX control. In addition to GIS, this solution also provides real-time communications between the home office and the remote locations.



Conclusions
Computer and communication technologies will continue to encourage Internet GIS implementations. With a wireless modem (costing as low as $30 a month), remote users can access an Internet based GIS database with unlimited connection time. The GIS industry is fortunate to see major GIS vendors offering programmable objects and controls allowing other applications to include GIS capabilities. In the next few years, the ability to access GIS from the Internet and the feasibility to integrate GIS with other applications and devices will broaden the scope of current mapping systems and allow GIS to reach a much wider audience.

It wasn’t too long ago when we were proud of operating on a 386 20Mhz computer with 40MB of hard disk space and Bill Gates was skeptical of the Internet’s potential. But now, computers are running several hundred times faster, and Mr. Gates is fighting to gain more share of the Internet market. Internet related technologies are destined to elevate GIS to a level we can only imagine. That time will surely come sooner than anticipated.

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