1998 NW ESRI User Group Conference
Washington Cadastral Framework Project
G.S. Tudor, PLS Carrie Wolfe
Project Manager Framework Coordinator
E-mail: Greg.Tudor@wadnr.gov E-mail: Carrie.Wolfe@wadnr.gov
Voice: 360-902-1542 Voice: 360-902-1639
Geographic Information Section
Information Technology Division
Washington State Department of Natural Resources
PO Box 47020
Olympia, WA 98504-7020
The Washington Cadastral Framework Project is a National Spatial Data Infrastructure (NSDI) demonstration project. The goals of the NSDI Demonstration Projects Program are to show the benefits of building partnerships, sharing costs and coordinating work, standardizing data and tools, speeding up application development, improving and documenting data, resolving data conflicts, and sharing data. Phase 1 of the Washington Cadastral Framework Project is to implement the Federal Geographic Data Committee's Cadastral Data Content Standard, to show how to integrate data from several representative partner sources (federal, state, regional, county, city, and private organizations), and to provide the integrated data over the Internet to Framework partners as a benefit of that partnership. The cadastral data standard is based on the FGDC Cadastral Subcommittee's work, but with some revisions, extensions, and implementation details. Statewide data was converted from the Department of Natural Resources Arc/INFO POCA, PLS-PT, and MPL coverages to Arc/Oracle SDE layers built from the modified FGDC standard. Snohomish County, Longview Fibre Inc., and Bureau of Land Management partner data are being integrated, and integration process standards are being developed. The goal of Phase 2 is to automate the data validation and integration process so that minimal intervention for enforcing standards is necessary in the editing environment. Integrated cadastral data is now available to Framework partners over the Internet through the ArcView Internet Map Server.
Cadastral data are defined as the geographic extent of the past, current, and future rights and interests in real property including the spatial information necessary to describe that geographic extent. Cadastral data include Public Land Survey records, political sub-division boundaries (i.e. city, town, county), ownership information (both public and private), and comprehensive plan and zoning district data.
During Phase 1 of this project, a multi-sector cross section of organizations in the state have partnered in the effort to develop and test an interorganizational partnership approach to create, manage, and distribute base cadastral data for the state of Washington. Some of the partners have highly developed GIS data and applications. Others are just beginning. Partners have contributed funds, in-kind hours of service and input, or a combination thereof. A wide variety of business requirements and expectations of the Washington State Cadastral Framework have been discussed and identified.
The Department of Natural Resources (DNR) has played a leadership role, as well as a partner role in this project. As a partner, the DNR has many interests in the Cadastral Framework Project. The Public Land Survey Office (PLSO) is a part of the DNR and serves as a statewide survey repository. The PLS data that is maintained by the DNR is already a statewide integrated dataset. The State Surveyor, Dave Steele, is a project sponsor. The Land Records Unit, the Resource Mapping Unit, and the Aquatic Resources Division of the DNR also manage cadastral data and have been participating in the project.
There are several reasons the department has taken a leadership role. With the establishment of a Framework Coordinator position, in addition to other DNR GIS management staff, the department has been able to play a role in Framework development on the federal level as well as the state level. The DNR also coordinates the Washington Framework Management Group (FMG). The FMG consists of federal, state, local, private, and tribal organizations that are involved in building framework data within Washington. The FMG identified cadastral data as a high priority framework theme to develop. Thus, the project was initiated and partners were recruited.
Developing an application to update a spatial data set over the Internet is an ambitious undertaking, so the project was broken down into three phases. The first phase was to develop and implement an FGDC compliant data model, convert three existing DNR cadastral data coverages (POCA, PLS-PT, and MPL), and serve this data over the Internet. Phase 2 is to develop data exchange and edit environments, and integrate other internal and Framework Partner data. Finally, Phase 3 will be to develop tools and utilities for automating the partner data integration process. The development of Phase 1 is the subject of this paper.
The FGDC Cadastral Data Content Standard models the business of tracking rights in land conveyed through transactions in which the extent of the land is based on a legal description. In the model, legal area descriptions are compiled from legal description components that are individual Public Land Survey and civil subdivision areas, metes, bounds, and corners. The extent of the land and land rights come together in the parcel. Transactions show agent interests in the parcel. Restrictions affect the usage of parcel rights. Document sources index where to find legal descriptions, restrictions, transactions, boundaries, agents, corners, and coordinate measurements in the public record or in private files.
Data analysis was approached from several directions: existing DNR coverages, the FGDC Cadastral Data Content Standard, a partner requirements survey and review, and developing DNR projects. In the context of existing DNR data coverages, a technical analysis was performed to document the physical structure and the foreign key relates, and also to logically normalize the entities, attributes, and relationships. From the FGDC Cadastral Data Content Standard, physical elements were made more logical and super/subtypes were identified after Cadastral Subcommittee members reviewed the intent of the model with us. Some extensions were also made to the model to include coordinated geodetic points and monuments in the model. The Framework Partner survey was developed from the FGDC Cadastral Data Content Standard. The survey asked partners which of the entities and attributes they needed used. In terms of developing DNR projects, the Automated Tract Book Project became the active model for development of an FGDC compliant data model. Aspects of the Aquatic Land Ownership Project were also included in the development data model. The complexity of this approach is apparent, and some of the modeling will have to be reworked in prototyping.
Several things were learned from the September 1998 National Spatial Data Infrastructure meeting. The data content standards are to be the minimally attributed set of data necessary to conduct the business of an FGDC theme. Extension of the data content standard should be done on the business proprietary side, not the common partner database. From the trickle of partner requirement changes that come in outside of review sessions, it is apparent that some partner requirements were missed. The FGDC Metadata Content Standards would provide a better means of understanding partner requirements than the Cadastral Data Content Standards. Partner requirements should be extracted from the set of metadata documenting the data sets that Framework Partners use for their cadastral business, that Framework Partners commonly exchange with their cadastral business partners, and that Framework Partners would like to get from exchanges of cadastral data.
Prototyping and Physical Design
The complexity of the logical data model required resolution of the many possible implementations of the model. Prototyping was used in several cases to force resolution of the super/subtype entities. Lack of data to fill in some of the relationships between tables is another problem worked out in the physical implementation. Being new to the object oriented feature model of SDE also made prototyping of implementation ideas necessary. At first individual extracts of data sets from coverages were made for SDE. However, it was apparent that these could not readily be converted back to an integrated coverage format for editing in a conventional Arc coverage environment - most of the tools for editing in a SDE/ArcView shape format have not been developed or have not had the time to mature. The approach being taken is to extend the base coverage to a region format and then convert to SDE layers based on the region subclasses. These layers can be merged back together into a region coverage for editing. The FGDC Cadastral Data Transfer Standard is also in terms of a Arc/INFO regions coverage, however, it has no coding scheme and may be difficult to use for data exchange.
ESRI's ArcView Internet Map Server was chosen to serve the data over the Internet. ArcView's Database Access extension allows a direct connection to the SDE database. ArcView's IMS extension serves GIS data for map display and query through a customizable standard interface. The IMS offers several formats of standard interfaces as multiple frames. The layout and number of these frames is easily adjusted in the master, and the content of several frames may be modified by editing the HTML. JAVA enhancement of the standard Web page and the Map Café viewer are also possible.
As each SDE layer was implemented, a database theme was created in ArcView to display the layer and allow queries. In some cases, a database query had to be constructed to filter the data from the layer. The activation scale was set for each of the themes so that they are displayed and can be queried at an appropriate level.
Modifications were made to allow the Identify button to return query results from all active themes instead of just the first. One change to Identify was the retention of the defined database query because Identify was nullifying the defined query and producing unexpected results from the filtered theme .
Downloading of cadastral data sets is now in prototyping. Currently, the Public Land Survey townships and sections are available to Framework Partners by county or the state. Additional layers will become available, and modification of the FGDC Cadastral Data Transfer Standard will be investigated. Interactive selection of data within a rectangular envelope is being developed with JAVA. More tools for selecting data to download will be developed as needed.
The Cadastral Framework Project is different from other data coordination efforts in a number of ways. It is not just a government project. It intends to fulfill the business needs of public and private organizations. It is not based on old data sharing relationships. Project partners are working to develop a new way of doing business; where partners share responsibilities, commitment, benefits, and control. It is not a one-time effort. This project is seen as a start. In the future, additional organizations will participate and contribute data. Rather than entering and using cadastral data as separate organizations, this project allows for less duplication of effort, cost sharing of data collection and maintenance, and the opportunity to share data in a standard format.
Cadastral Subcommittee, Federal Geographic Data Committee. Cadastral Data Content Standard. Reston, VA. December 1996.
Cadastral Subcommittee, Federal Geographic Data Committee. Cadastral Data Transfer Standard. Reston, VA. February 1998.
Federal Geographic Data Committee. Content Standards for Digital Geospatial Metadata Workbook. Reston, VA. March 1995.