As with any major undertaking, we faced several issues along the way. Some of these were minor, while others had the potential to significantly disrupt the project’s outcome. Some are simply factors that needed to be taken into account during the construction of the application. These issues are described
below, in no particular order.

System Requirements

     As stated above, the application uses the ArcIMS Java Viewer. As such, it has unique system requirements for the end user. It requires two downloads – the JRE, and the IMS Viewer. Although they only have to be downloaded and installed once, it does add an extra step for the end user.

     The Java Viewer is a “streaming” viewer. Instead of sending a static image in response to a request, as the HTML Viewer does, it maintains an open connection between client and server, with data constantly flowing back and forth. It is this stream that allows functionality such as live zooming, without the need for the user to click an “Update Map” button. This functionality comes at a price, however. It requires the user to have a relatively fast computer, and a broadband (DSL, cable, LAN, etc.) connection to the Internet.

     One of the most limiting system requirements is that of supported operating systems and web browsers. At the time of this writing, only Microsoft Internet Explorer 5 (and above) running on Windows (9x, ME, NT or 2000) is supported. Netscape is not supported, as it does not allow the running of Java2 applications, necessary for the Java Viewer to function. This lack of interoperability means that users of Macintosh, Linux and other operating systems are incapable of viewing the site. In the spirit of interoperability and open standards, we sincerely hope that ESRI rectifies this situation soon.

Inadequeate, Incomplete and/or Incorrect Data

     When we began the project, we received a dataset from Jasper Stoodley. A previous Geography 452 group used this set, also for a project on the Burnaby Mountain development (their project site can be found at http://www.sfu.ca/geog452spring00/project2/. The dataset included the SFU buildings, roads and fields as well as the proposed development buildings.

     As we began working with the data, however, we realized that it was inadequate for our purposes. The previous group had obviously not intended their data to be used for analytical purposes. The campus buildings had been digitized in one large block, not as discrete entities. As such, when we tried to select the Classroom Complex, the entire campus was selected. After weighing our options, we took the steps outlined in Data Manipulation and created new coverages for the entire campus. This data then needed to be reprojected in order for it to be usable.

Missing Photos in the Panorama Sets

     After downloading the images captured for the viewpoint panoramas, it became evident that a few of the viewpoints were missing images. These were either damaged while being captured or not captured at all. The result is two or three interesting panoramas, as evidenced below.

Security

     Overall, our Java Viewer-based Internet application website is secure. Java provides a security framework, known as a “sandbox,” to establish an intelligent security system that consists of three major: the Java language, the Java complier and verifierand security managers in the Java runtime environment (JRE). If the veri-fier cannot confirm that the Java complier produced the code being loaded, the code will not be loaded and executed. On the browser side, the user is secure in that the Java “sandbox” does not allow the applet(s) to modify the local file structure (i.e. no file writing, etc.). Thus, no viruses into can corrupt the local memory or system.

     However, Java applets are not error or problem free in terms of security. This conservative system imposes some restrictions on what can be achieved by using the applets in the development of Internet GIS. For instance, applets are prevented from accessing machines on the network other than the computer from which the applets were originally loaded. This can potentially lead to serious problems in development the Internet GIS application as a distributed system. Furthermore, because applets do not allow users to write on their local systems, data cannot be written nor saved to the user’s local machine (Peng, 1998).

     In the future, as overall Internet security improves, Internet GIS will become more secure and more flexible.

Quality of Data

     Problems regarding the quality of data and the depth of our Internet GIS application have been compounded by uncertainty (for example, we were not able to obtain the heights of newly proposed buildings) and by time constraints (under three months allotted to complete the project). More sophisticated viewshed analysis would have been performed if there were data about the SFU building heights.

Arbitrary Selection of Viewpoints

     In reality, just about any point on campus could be chosen as a viewpoint for our project; however, these points were chosen based upon judgment on where key places would the intended audience would be interested of knowing its viewshed. This can potential introduce bias and criticism to where what other viewpoints on campus could have been included or not.