Brent Mainzinger
The Sidwell Company
675 Sidwell Court
St. Charles, IL 60174
630-549-1000
630-549-1111
bmainzinger@Sidwellco.com
INTEGRATING TAX CYCLE AND CAMA DATA INTO AN MGE GIS
PROJECT, AND ANALYZING IT FROM GEOMEDIA AND ArcView GIS
SOFTWARE
Abstract: Black Hawk County, Iowa, has recently accepted delivery of a geographic
information system (GIS) project containing cadastral information for more than 60,000
parcels of land. This project was delivered as an Intergraph MGE project. The tax cycle
software was developed by the county's MIS Department, and the CAMA system is a
product of Vanguard Appraisals. Cadastral maintenance is performed using
MicroStation Geographics software.
Real-time integration between the GIS and tax cycle system was accomplished by
passing parcel numbers and program instructions between applications by using
Microsoft Windows NT-based AS400 emulation software and DDE technology. This
integration is running on nine stations. Thematic integration is accomplished through
an application that runs timed SQL updates from the AS400 to Microsoft SQL Server
residing on the Windows NT network.
Desktop analysis can be performed using Intergraph Geomedia or ESRI ArcView GIS
software. Geomedia is installed at 13 stations. ArcView GIS software has been tested,
and is able to spatially analyze the same data because GIS intelligent parcel shapes are
included in the MGE data set.
PROJECT SOFTWARE OVERVIEW
The Black Hawk County, Iowa, geographic information system utilizes software from several
vendors to facilitate specific tasks within the project. MicroStation Geographics software, a
product of Bentley Systems Inc., is used as the preferred platform for maintenance of the parcel
base maps. This product has been significantly customized by macro application programs and
user interfaces developed at The Sidwell Company. Adherence to cadastral mapping standards
and consistent map publication formats are encouraged by use of this macro library. Bentley’s
GeoOutlook is used to provide quick desktop access to the parcel base map.
Intergraph’s MGE product is used for more complex GIS analysis tasks. Geomedia is utilized for
desktop mapping tasks in several offices. MGE, Geographics, GeoOutlook, and Geomedia are
utilizing the same data set without any data conversion.
Tax cycle administration is being accomplished with software developed by the Black Hawk
County MIS staff which resides on an IBM AS400 minicomputer. Computer-assisted mass
appraisal (CAMA) data are managed with VCS software from Vanguard Appraisals.
Most recently, the county has added ESRI ARC/INFO and ESRI ArcView GIS software to its
software suite in an effort to better support users of county data who might only be comfortable
with ESRI software platforms.
Most offices utilizing the GIS have standardized on Windows NT workstation and server
technology. The GIS utilizes Microsoft SQL Server as the corporate database warehouse.
REAL-TIME INTEGRATION
Real-time integration between the tax cycle data and parcel maps was identified as a system
requirement early in the project. The goal was to utilize the existing tax cycle inquiry programs
residing on the AS400 to query parcels of interest, and then display the related parcel maps from
the GIS data set. Emulation software allows the AS400 inquiry programs to be accessed from
users at Windows NT workstations. Reflections and Client Access software packages are being
used as Windows NT-based AS400 emulation tools. The GIS parcel maps are accessed from the
same stations utilizing GeoOutlook software, which was selected because of its impressive
inquiry response time. A bridge between the two systems was created using SIDBase software
written at Sidwell. This software sends parcel numbers back and forth between the AS400
emulation software and GeoOutlook. A sister portion of SIDBase resides within the emulation
software that sends and receives parcel numbers and associated instructions to and from the
AS400.
By using this approach, the existing AS400 tax cycle software has been used within the real-time
GIS inquiry application without any modification.
This scenario enables a user to search for a parcel in the map database using the existing AS400based tax cycle administration application, which is running in a window on a Windows NT
station. Once the desired parcel is isolated, the user selects a button on the toolbar within the
AS400 emulator. This causes the software to send the parcel number of the currently selected
parcel to the map, which is running in another window on the same Windows NT station. Upon
receiving the parcel number, the mapping application retrieves the appropriate map file, isolates
the parcel of interest, zooms in on the parcel, and draws the parcel map at an appropriate scale.
The content of the map display is predetermined by setup variables. The user is not required to
perform any operations within the mapping software environment.
The inverse operation is also supported. A parcel can be selected on the map and sent back to the
AS400 emulation software with the push of a button. Upon receiving this instruction, the
SIDBase script running within the emulator sends the necessary keystrokes back to the AS400 to
perform a parcel number inquiry. The associated inquiry screen is displayed to the user.
This approach utilizes AS400 emulation and desktop mapping software that are residing on the
Windows NT station anyway for use independently of one another. By building the integration
bridge with these components the existing investment is leveraged.
SYNCHRONIZATION OF GIS AND TAX CYCLE/CAMA DATA
The previously described approach is effective and efficient for real-time, single-parcel inquiry.
However, it does not make the tax cycle data available to the GIS for thematic mapping and
spatial analysis functions.
To provide this capability Sidwell developed a data integration software application utilizing
Microsoft Access operating in conjunction with a program created by the county’s MIS
Department. Tax cycle records that changed during the day are selected during the coming night
by the county's AS400 program. These records are written to a set of text files on a Windows NT
Server. Later during the night the Microsoft Access application automatically reads these text
files and performs SQL updates against the GIS database residing in SQL Server.
This same approach is currently being applied to the CAMA data residing in VCS software. In
addition to making data available to the GIS, Vanguard has developed an application that
replaces internal codes that reference lookup tables into English definitions for ease of use. For
example, instead of seeing a code of “2” in a column assigned to display information pertaining
to basements, the user will see meaningful text such as “half-finished.” The GIS data warehouse
will be updated against the CAMA data by the same application that manages the tax cycle
updates.
This scenario permits the GIS to access to information that is never more than one day out of
date, resulting in GIS analysis that is based on current data, and is in sync with tax cycle data.
PREPARATION OF INTEGRATED DATA FOR ArcView GIS SOFTWARE
Geomedia can directly utilize Black Hawk’s GIS data. For many internal users this is a
reasonable approach. However, the popularity of ArcView GIS software cannot be dismissed,
and the need to make Black Hawk data available in an ArcView GIS software environment has
become obvious. Using existing functionality within MicroStation Geographics and ESRI
ArcView GIS software in combination with a little creative scripting we stumbled upon a
solution.
Although the ArcView GIS software’s CAD READER extension can read the county’s maps in
their native format (DGN), the fact that 430 DGN files were housed within the GIS project made
this approach difficult. Additionally, the MGE Reader extension to ArcView GIS software
proved to be too slow and cumbersome. As a result, the workflow outlined below has been
established.
1. A macro was created that is run on every parcel map file upon completion of parcel
editing. This macro creates shapes for each parcel, and associates a pointer from each shape to
the master parcel attribute table in the GIS. The macro runs in about 10 seconds, so the parcel
maintenance workflow has not been significantly affected.
2. A script was written in EDG, the MicroStation off-line graphic editing environment,
which extracts the parcel shapes from all 430 base maps into a single DGN map file. This script
runs in about six minutes.
3. The resulting DGN is read into the ArcView GIS software environment using the CAD
READER extension. As the ArcView GIS software reads the features from the DGN, the CAD
shapes are interpreted as polygons.
4. After the parcels are displayed, an attribute table is created for the theme using the
theme table menu option in the ArcView GIS software environment. As this is done, the index
between the graphic elements and the master parcel attribute table (MSLINK) is automatically
extracted from the CAD DGN file and added to the theme table.
5. The ArcView GIS software's SQL Connect feature is used to access a relational view
that has been previously established in SQL Server which joins selected information from
CAMA, tax cycle, and the master parcel attribute table which relates parcel number to graphic
map elements. Tax cycle and CAMA data, and master parcel attribute table, are joined by parcel
number. The index to graphic mapping data is carried into the view from the master parcel
attribute table. In the MGE community, this master link is referred to as MSLINK. In the ESRI
community it is commonly referred to as the #ID.
6. An ArcView GIS software JOIN is then used to relate the MSLINK in the theme table to
the MSLINK in the parcel attribute table (which is actually a view containing tax cycle and
CAMA data extracted from SQL Server).
7. The ArcView GIS software create shapefile menu option is then used to create a
standalone shape file that contains all 60,000 parcels and associated tax cycle and CAMA data.
The resulting shape file can be used for virtually any ArcView GIS software-supported analysis
including labeling, buffering, or graduated thematic map analysis. The draw time of this 60,000
parcel shape file in the ArcView GIS software environment is less than six seconds on our
computers. In addition, this shape file is an ideal mechanism for disseminating information to
outside users. It can be utilized by a menagerie of software tools, including several that are
available for free from their respective vendors.
During the URISA presentation, this technique will be demonstrated with live data.
CONCLUSION
Data integration is never as simple as it sounds. In this project we have attempted to give
preference to simple solutions wherever possible, leverage existing investment wherever we can,
and realize that no one vendor is best at everything. Hopefully, the data integration techniques
and MGE / Geographics data porting procedure outlined here will be useful to other conference
attendees.