CountyView: Getting the Data to the User

Abstract:

This paper will discuss the customization and use of ArcView for a countywide GIS data access application called CountyView. CountyView was developed by Pierce County GIS to give a wide spectrum of county users easy and quick access to GIS data. Prior to the deployment of CountyView the access to GIS data was limited mainly to those who knew how to use ArcInfo and knew where the data resided. Many potential county users were denied access to GIS data even though their work involved tasks which could be made simpler with even the most basic of GIS data. CountyView was developed with these users in mind. It was meant to present county GIS data in a organized fashion with an easy to use set of tools to manipulate and analyze the data. Through a series of drop down menus GIS data themes are added to and removed from a View. Legends and display scales are provided for the user when the theme is added to the View. Besides access to GIS data, CountyView also provides simple application and query tools to give the user an effective means for working with GIS data. Meta data for each of the themes is also provided with the click of a button. Another button provides the complete suite of ArcView tools and buttons for the more advanced ArcView users. ArcView's effectiveness and limitations for this type of application will be discussed.

CountyView is Pierce County's GIS data viewer. GIS data has existed in Pierce County for about six years, but not until the introduction of CountyView one year ago was this data available to most county employees. Previously only those who were actively involved with GIS software or were building GIS data knew where the data resided and how to get to it. This situation was not acceptable to those who were helping to pay for GIS and were waiting to use the data in their everyday tasks. The introduction of ArcView 2 with its Avenue programming language provided the key to making easy access to the GIS data. CountyView is written using Avenue as an ArcView application to fill the need of providing easy access to Pierce County's GIS data. This paper will describe some of the decision making process used in building this application and features added to ArcView to create CountyView.

Pierce County GIS data has been collected for more eight years during GIS database development in the county. This process is ongoing with many departments within the County gathering and storing this data. These departments include Planning and Land Services (PALS), the Assessor Treasurer's Office(ATR), Surface Water Management (SWM) and many others. Although this data has been shared between departments and stored in shared UNIX file systems, access to the data was still limited to a few privileged GIS users. Getting this data to the desktop was the challenge that the GIS department faced. The release of ArcView 2.0 with its Avenue programming language seemed to provide an answer to the dilemma Pierce County GIS data users faced. ArcView provided an easy to use interface to many GIS functions that previously were only available to those steeped in GIS technology. Therefore it seemed possible that this set of GIS tools with some customization could unlock the door to GIS for many county employees. There were however many issues and challenges to overcome to make ArcView the comprehensive GIS tool Pierce County was looking for.

As ArcView existed, out of the box, access to GIS data still demanded that the user know where that data was stored and that access privileges to the data were given to the user. CountyView was first conceived and brought to life as a customization of ArcView to provide easy access to the wealth of GIS data available in Pierce County. Rather than letting the user navigate to a directory where the data was stored and then add that theme to the project. It was decided that the data needed to be available at all times with just a click of the mouse. The first attempt at providing this type of interface was to store all the available themes in the View window and allow the user to turn on or off the visual display of that data. This approach quickly proved too cumbersome as scrolling through long list of themes in a single view (in this case more than 100 themes) was tedious at best. Also an approach such as this caused CountyView to take an inordinate amount of time to start.

A second approach, having multiple views each with a particular category of data already loaded, worked somewhat better, yet initialization of the project was still a lengthy process. The approach eventually chosen to best suit the needs of CountyView clients was to provide a menu bar with categories of data organized by type.(Figure 2) The menu choice categories gave the user an organized way of locating the data needed for their project and an uncomplicated way of accessing GIS data. Early prototypes added the data through an Avenue script locating the source files and building legends as needed. It was soon discovered that all data needed a legend that was consistent each time the data was added. Legends then were created and saved to .avl files but even this proved to have its problems especially when legends consisted of only the default classification on no particular field. Legend consistency problems were solved by the use of odb(object database) files to store each particular theme along with its associated legend. The odb files were read into the project each time data was needed and provided a quick and efficient means to storing themes.

With a click of the menu choice, the odb file is read using the menu tag which stores the name of the odb file needed to access the theme. Once read the theme is entered into the current view and the menu choice is marked by a greater than (>) signs and less than (<) signs as brackets. These brackets indicate that the theme already exists in the current view.(Figure 3.) Clicking on the menu choice a second time will remove the theme from the current view and also remove the brackets around the entry. Also notice the use of an Overview window in CountyView. This helps the user keep track of where he is within the county in the main view at any particular time

One of the specifications of CountyView, that is nearly as important as ease of use, is quick response time. As discussed above initialization response time was one of the key factors in using odb files for adding new data. Response time also facillitated the use of ArcView Shape files for most of the data themes. The difference in response time between an ArcInfo Library layer and a shapefile of the Library layer was quite significant. The spatially indexed shape files drew faster on the screen by a factor of 2 or 3 times, in some cases even more. However this approach meant that there would be data duplication and the need for update and maintenance of the shape files dependent upon changes occurring in the source data. Most shapefiles then are under some sort of update cycle to maintain concurrence with the source data.

Each data theme is also accompanied by meta data. Meta data is, of course, the data about the data, or the data that describes the data. Included in the meta data is information about the data source, its accuracy, its scale, its owner, its attribute definitions and more. CountyView training emphasizes meta data by including a lengthy discussion of the importance of using and referring to the meta data when using any of the GIS data. This is especially critical when using more than one theme at a time. Meta data is a necessity and not just a nice "feature" in the CountyView application. In order to facillitate the use of meta data it was written in hyper text markup language (HTML). HTML makes it easy to jump from place to place within a document and allows it to be viewed by Internet browsers. CountyView's meta data is viewed using a Web brower, either Netscape or MicroSoft's Internet Explorer. It is accessed through a button, the blue M button (see Figure 2.), in CountyView which starts the web browser and displays the meta data in two frames. One frame displays the Contents of the meta data in the same organization as the Menu choices of CountyView.(Figure 4.) Clicking on the data index sends the user to the other frame which displays a small graphic of a map displaying the data being accessed and a button to display the meta data itself. Clicking the Meta data button displays the entire text of the meta data in a full window display with hypertext index making up the first few lines of the document.

Besides the data themes available through the menu choices there are also three data driven applications choices. These applications are data driven in that they are presented in order to look at data not easily displayed all at once. The first of these is a sheriffs department application which classifies and displays crime data by address, by pointing at the display, or by displaying all of a particular type of crime within Pierce County. A second application of this type is a yellow pages listing for the county. This data also can be accessed by address, a point on the View, or by business type. A series of popup menus lead the user through the contents of the Business listing. A final data driven application is the shown in the planimetric data which is available for only limited parts of the county. This data includes a long list of possible themes. Rather than listing them all as standard menu choices, which seemed to be difficult to contend with, the Planimetic choices are made from the menu of a second view. This view is displayed when the Planimetric menu choice is clicked. It lists all of the possible planimetric data choices in the scrolling View Table of Contents.(Figure 5.) Any theme checked in the TOC is added to the main view when the OK button is pressed in the Planimetric View. Clicking on the Planimetric menu choice again will clear all of the planimetric data chosen.

Other applications are also available within CountyView through the Button Bar. CountyView. CountyView itself is one of these applications. CountyView at startup comes with a pared down list of Menu, Button and Tool Bar choices. The additional buttons of CountyView are displayed in color icons as opposed to the black and gray buttons of standard ArcView. One of those buttons is the red "add" button. (Figure 2.) When this button is pressed the full suite of ArcView menu, button and tool bar choices along with CountyView's additions is available.(Figure 6.) The CountyView "Lite" GUI was developed with the casual user in mind. Here the choices are fewer and geared to the uses of the casual user who has not had training in the full capabilities of ArcView. The switch to the full ArcView GUI at the same time gives more experienced users access to all the tools and capabilities they need to build their applications.

The first of the button applications are the locator applications. There are two of these one: the Geocode Locator which uses the standard ArcView Geocode Locator. This script was modified to include a street name alias table to find streets which have different names on each side of the street. A batch geocoding application was also added using the same street name alias table. Another locator, the "Bulls Eye" button, provides a menu of locator choices, included is a Tax Payer Name locator, a Tax Parcel Number locator, a Plat Name and Number locator and an RTSQ locator. These locator methods were requested by the ATR and PALS departments. They use the typical search methods of these departments while searching Parcel data. Each of these locator applications is optimized for speed of retrieval. The Tax Payer Name locator starts with a message box requesting the Tax Payer's last name. The initial search is done on the last name field which is indexed and returns a list of all records with the requested last name.(Figure 7.) A choice can then be made of one or many records from the list which then access the proper record or records by a record number. This makes for very quick access to the parcel desired it is then selected and zoomed to. The Plat Name locator works in a similar way, while the Parcel Number, Plat Number and RTSQ locators all access an indexed field within the parcel land layer.

A Second Application available on the Button Bar is the Census Application. It uses the "people" button on the button bar. Census data is a challenge to deal with because of the width of the data. Each Census data tape comes with many fields or columns and one row for each block group. Of the two tapes available in CountyView Tape #1 has 985 fields while Tape #3 has over 3500 fields. The names of each of those fields can be can be as many as 100 characters long.(Figure 8.) CountyView then uses a series of list message boxes to give the user a way to navigate through the names as they are arranged in categories and sub-categories. Finally with the proper field selected the query builder is displayed with that field selected. The Census App button can be chosen a second time for reselections from the query builder. This application was requested by the PALS to aid in using census data in their work.

The final application on the button bar is called the Owner Notify application. Owner Notify allows the user to buffer around any selected feature for parcels. Parcels are selected within a requested distance and by adjacency, one or two parcels deep. Through the use of a separate GUI the selected parcel set can be visually edited by adding or subtracting parcels. It then produces a mailing list of the selected parcels that are numbered on both the list and the view. A map of the view display can also be produced corresponding to mailing list. The list can be printed or saved to a file for use in other software to produce mailing labels, etc.

CountyView was developed for use within the Pierce County Government and has been widely accepted by many if not all of the departments within the county. It is being used by those without any GIS background and by those who have had years of experience in GIS. It is being used by surveyors, engineers, planners, cartographers, scientists, managers and politicians. For these reasons it needs to be easy to use and it must be able to run on nearly every desk in the county and also a few outside of county government. This wide reaching demand means that it must be flexible in its implementation. Pierce County's GIS data has historically been stored on a Unix server and continues to be today. However with the advent of CountyView the data needs to be accessible to either Unix systems or PC's. This access has been made possible through the use NFS and TCP/IP.

CountyView was written with both PC Windows and Unix systems in mind. The project(.apr) file resides on the Unix box, but is written to be system independent. This is accomplished primarily by using system variables to describe pathnames to the GIS data. In some departments, where desktop machines have already been using Unix GIS applications through X emulators or in which there is little money to update current hardware to the levels needed to run PC ArcView, Unix ArcView is the system of choice. Access to CountyView is gained through an X window emulator on the desktop PC, the computer power needed to run the emulator is much less than is needed to run PC ArcView locally. However this solution involves careful planning for software licensing and the use of server resources to run the number of concurrent sessions demanded at any one time. As the number of users continues to grow the usefulness of the Unix solution is becoming diminished. CountyView is now also being served off network PC filesystems. The biggest constraint on this solution is having a speedy enough network system to handle the flow of data across the various county token rings. It has been found that anything less than a T1 line becomes prohibitive to the efficient use of CountyView on the PC. This has been of particular concern as more and more agencies and businesses outside of Pierce County Government have become insistent on having access to CountyView. At network speeds slower than T1 only the Unix version was found to be usable since only the graphic images need to be transferred across the network when using X emulation. However the need for on site printing and local file access and storage make the Unix solution still a problem for many users.

CountyView is in the process of being moved to ArcView 3.0. This transition has not been without its challenges and its rewards. Since CountyView is dependent upon creating customized Graphical User Interfaces(GUI) this meant that all of the AV2.0 buttons, tools and scripts went with it. All of these had to be updated to the new AV 3.0 buttons, tools and scripts where they had changed. This caused no small amount of painstaking comparison of the old GUI to the new. The good news is a repeat of this process at the next release is probably avoidable with the use of extensions. CountyView can be rewritten as an extension of ArcView and just those buttons and tools that change need to added to the project and can be deleted when not needed. The next roll up should be easier. Also the way in which all GUI's are handled as Doc's in the Project window make for easier handling of requests for multiple views. This was a stumbling point in earlier versions of CountyView. Of course there were other "small" problems which delayed to move to ArcView 3.0, such as the fact that ArcView 3.0 built a different type of attribute index. This caused those with ArcView 2.0 projects to have to rebuild indices each time their project opened. This problem was solved for the PC with the ArcView 3.0a patch. However, we have yet to see a similar patch of the Unix version which is delaying our ability to move up to 3.0 yet for CountyView. The ability of PC ArcView to view AutoCad DWG files is a feature eagerly awaited by many CountyView users and is a further argument for the use of the PC version.

The future of CountyView looks more and more like it belongs on the Intranet and Internet. The introduction of the ArcView Internet Server appears to be a step in this direction. Many of the problems of printing, network speed, installation, and computing power could be solved by these type of applications. CountyView is expected to evolve to make use of these new technologies in order to continue to provide GIS data to as many Pierce County users as efficiently as possible.