Copyright 1999, American Congress on Surveying and Mapping.
Washington State Cadastral Framework Project: Implementing the FGDC
Cadastral Data Content Standard and Integrating Data from Multiple Sources
Gregory S. Tudor and Carrie Wolfe
Greg Tudor and Carrie Wolfe are, respectively, Cadastral Framework Project Manager and Framework Coordinator at the Geographic Information Section, Information Technology Division, Washington State Department of Natural Resources, PO Box 47020, Olympia, WA 98504-7020, Telephone: 360-902-1542, Facsimile: 360-902-1790, E-mail: Greg.Tudor@dnr.state.wa.us, E-mail: Carrie.Wolfe@dnr.state.wa.us, Web: http://framework.dnr.state.wa.us.
The Washington Cadastral Framework Project is a National Spatial Data Infrastructure (NSDI) demonstration project which will help 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. The Washington Cadastral Framework Project is broken down into two phases which are pilot projects to implement a standard cadastral data set and to integrate cadastral data from multiple data sources. Phase 1 (1997/09-1998/09) involves extending and implementing the Federal Geographic Data Committee (FGDC) Cadastral Data Content Standard in SDE/Oracle, populating the database with initial data, developing metadata on the data, and distributing the data over the Internet to project partners. The Cadastral Data Content Standard was extended to work with other Framework data content themes: Geodetic Control, Hydrography, Transportation, and Governmental Units. Phase 2 (1998/09-1999/09) involves adapting the FGDC Cadastral Data Transfer Standard for data exchange, integrating data from several representative partner sources (federal, state, regional, county, city, and private organizations), developing update locking procedures for long transactions over the Internet, and automating the integration process so that minimal intervention is required for enforcing standards and resolving conflicts.
Cadastral data are the geographic extent of the past, current, and future rights and interests in real property. Rights and interests are the benefits or enjoyment in real property that can be conveyed, transferred, or otherwise allocated to another for economic remuneration. (FGDC, Cadastral Subcommittee 1996.) Typically, cadastral records are kept by public and private surveyors, county recorders, county tax assessors, land title companies, private land management businesses, private land agents, and government agencies entrusted with public lands. Each organization keeps the records which are necessary to conduct its business. Surveyors measure and describe land; they keep records of their surveys and legal descriptions. Counties are responsible for publicly recording business transactions including conveyances, easements, leases, and sales from the land, and they keep these records. County tax assessors are interested in the value and usage of land as the basis of local government revenue. Land title companies duplicate the records of land transactions and add value by spatially indexing those transactions. Private land managers, such as timber, railroad, and mining companies, along with government agencies managing public lands, must track the extent of their large and dispersed holdings and must also track any encumbrances and restrictions placed on those holdings which limit the use of the land. Private land agents, such as developers and realtors, watch the transactions of land closely for investment and marketing. Each organization keeps a specific and detailed proprietary database of its business interests. All of these organizations conduct business among each other, and many are interested in communicating their land holdings and transactions to facilitate their business operations. The goals of this project are to develop a basic information standard for communications about land holdings and transactions, create a common database of cadastral information, and implement a method of communicating cadastral information between organizations and the common database.
Washington Cadastral Framework Background
The Washington Department of Natural Resources (DNR) has many interests in cadastral information. Washington became a state in 1889 and took possession of all aquatic lands and a selection of non-private uplands. The DNR now manages about 2,000,000 acres of aquatic lands and 3,000,000 acres of uplands held in trust for the public. The State Land Survey Office of the DNR maintains a statewide data set of the Public Land Survey System network, corners, and state ownership parcels - POCA (Washington Department of Natural Resources 1997b). The Land Records Office maintains the documentation of state land ownership, easement, resource sale and lease transactions and is in the process of automating these records into a data set. The Resource Mapping Section of the DNR collects ownership, administration, and management information from other public agencies and maintains a data set of major public lands inventory - MPL (Washington Department of Natural Resources 1997a). The Aquatic Land Ownership Unit is building a data set of the aquatic subdivisions of land and state ownership parcels. One of DNR's interests in the Cadastral Framework Project is the completion and integration of these cadastral data sets; all of these data sets are being contributed for integration with the framework cadastral database. Another DNR interest is the conversion of its Arc/Info coverage database into a SDE/Oracle feature database (Arc/Info and SDE are proprietary geographic information system software from Environmental Systems Research Institute).
The Department of Natural Resources has a great interest in improving the quality of spatial data and developing standards for distributing spatial data in general. The DNR has been actively participating in many geographic information system cooperative initiatives to set standards of spatial data communication, integrate spatial data sets, and provide methods of accessing spatial data sets. As a member of the Washington Geographic Information Council (WAGIC), the DNR has been actively providing direction for improving government geographic information products and services. In the Data96 project initiated in 1994, the DNR worked with private, tribal, local, state and federal organizations to complete existing transportation, hydrography, land survey, and topography data sets. The data was put into a common format and distributed to the partners. The WAGIC was awarded an FGDC grant for the Washington Clearinghouse in 1995. The clearinghouse is a searchable national catalog of metadata allowing users to find existing data sets and their data sources. The DNR provided metatdata for six data sets now available on the Washington Clearinghouse Node. An extension of the clearinghouse concept to a searchable catalog of prospective projects would allow users to locate partners for developing data sets that do not now exist.
The Washington Framework Management Group (FMG) was initiated in 1996 to direct the implementation of the NSDI framework strategy within Washington State. The FMG was charged with coordination and facilitation of the statewide geospatial framework. At that time, the Cadastral Framework Project and Hydrography Framework Project were identified as high priority targets for Washington framework development. Later, the Washington Transportation Framework Project was identified for development. The DNR created a framework coordination work unit in 1997 to support the FMG and facilitate and coordinate the framework projects. Coordination of framework efforts has allowed the DNR to participate at a national level as well as at a state level. In 1998, the FMG was recognized as a subcommittee of the WAGIC. (WAGIC 1998.)
With the DNR playing a leadership role in supporting the Framework Management Group, the DNR began work on the Cadastral Framework Project as the highest priority. The DNR began recruiting partners, started scoping the project, and hired a project manager to plan and oversee the project development. The DNR wrote a Framework Demonstration Project Program grant proposal for the project which was approved for $65,000 in 1997. After completion and approval of a project feasibility study by the DNR's Information Technology Board, the project started up. A follow-up grant proposal to help fund phase 2 of the project was submitted and approved for $99,000 in 1998.
A cross section of federal, state, county, regional, and private organizations have joined in the effort to develop and test an inter-organizational partnership approach to create, manage, and distribute base cadastral data for the state of Washington. Currently, project partners include: U.S. Bureau of Land Management, U.S. Bureau of Reclamation, U.S. Forest Service, U.S. Geological Survey, WA Department of Natural Resources, WA Department of Revenue, WA Interagency Committee for Outdoor Recreation, WA Department of Transportation, WA Department of Community Trade & Economic Development, Puget Sound Regional Council, Clark County, Douglas County, Spokane County, Stevens County Partnership, Thurston Regional Planning Council, Yakima County, Longview Fibre Inc., Weyerhaeuser Corporation, and Environmental Systems Research Institute (ESRI). 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 partnership has developed a charter and a partnership agreement. The charter identifies the goals and objectives of the partnership. The agreement specifies the benefits of joining the project partnership, and limits the use of the data and the application system during the development phase of the project.
The National Spatial Data Infrastructure means the technology, policies, standards, and human resources necessary to acquire, process, store, distribute, and improve utilization of geospatial data. The framework is the core set of geospatial data that are significant to a broad variety of users and the process of ongoing data maintenance. The framework data themes are geodetic control, orthoimagery, elevation, transportation, hydrography, government units, and cadastral information. Subcommittees of the FGDC coordinate development of these key data categories. (FGDC 1998c.) Working groups of the FGDC address issues that transcend data categories, such as archives, clearinghouse, facilities, framework, and standards. The Federal Geographic Data Committee coordinates the development of the National Spatial Data Infrastructure at a national level. The FGDC is using three major programs to generate interest and support development of the framework. The Framework Demonstration Project Program (FDPP) helps fund projects that demonstrate the sustained ability to develop the framework from local data sources. The Competitive Cooperative Agreements Program (CCAP) helps fund testing of different framework aspects. The NSDI Benefits Program helps fund projects that demonstrate the benefits of sharing data between organizations. (FGDC 1997.)
Developing an application to update a spatial data set over the Internet is an ambitious undertaking, so the project was broken down into two phases. The first phase was to develop and implement an FGDC compliant data model, convert existing DNR statewide 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 project partner data. As the database structure becomes more standardized and technology advances, a third phase may include development of tools and utilities for automating the partner data integration process. That final phase is not planned at this time.
FGDC Cadastral Data Content Standard
The FGDC Cadastral Data Content Standard models the business of tracking rights in land conveyed through transactions. The standard identifies the business components involved in land surveying and land recording and the relationships between each other. The main components of the standard are legal descriptions - including boundaries and corners, parcels, transactions, rights, restrictions, agents, and document sources (FGDC, Cadastral Subcommittee 1996).
In the cadastral data content model, the parcel is the focus of rights and interests in land. The extent of a parcel is compiled from legal description components that are individual Public Land Survey (PLS), mapped lots, metes and bounds, boundary, and strip descriptions (Wattles 1987). The descriptions may be associated to boundaries and corners which may also include direct references to ownership parcels. Transactions convey rights for parcels between agents. Restrictions are imposed on parcels by public agencies. Document sources index where to find legal descriptions, restrictions, transactions, boundaries, agents, corners, and coordinate measurements in the public record or in private files. Parcels and agents may be located by addresses. The standard also standardizes domains of allowable values for attributes of cadastral entities, and defines the cadastral entities and attributes. Educational materials on the standard are now on the web (FGDC, Cadastral Subcommittee 1998b).
Washington Cadastral Requirements Analysis
Data analysis was approached from several directions: the FGDC Cadastral Data Content Standard, a partner requirements survey and review, existing DNR coverages, and developing DNR projects. There are some areas of the FGDC Cadastral Data Content Standard that are modified in the Washington Cadastral Framework Project. The modifications are documentary clarification of the cadastral standard, restructuring the relationships between entities, and extensions to the content. A narrative of the intended use of the Cadastral Data Content Standard is not included in the standard itself. It took several months of data modeling and direct guidance from Cadastral Subcommittee members to establish and document how the Cadastral Framework Project would use the standard. Because of the technical and legal complexity of land surveying and land transaction, data analysts need extensive background to understand what they are working on. The entity and attribute definitions of the standard are expanded, and domain value definitions are added. Supertypes/subtypes are identified and broken down. The meaning of relationships are defined and labeled on the standard's diagram to assist in its use. A transition of DNR data sets from Arc/Info to Oracle/SDE was being conducted simultaneously with the adoption of the Cadastral Data Content Standard. A complete transition required that content extensions be made to facilitate the conversion of these within the context of the whole data model. The extensions include the additional framework themes of governmental units and geodetic control. Monuments were separated from corner points in the model to include geodetic control.
A project partner requirements survey was developed from the FGDC Cadastral Data Content Standard. The survey asked partners which of the entities and attributes they maintained, and of, those, which were shareable on the framework. It also asked for information on the entities and attributes that were needed by each partner, but not maintained by them. From the trickle of partner requirement changes that came in later through review sessions, it became apparent that some partner requirements were missed and that this should not have been the only approach. Metadata about partner proprietary cadastral systems should have been collected to identify existing partner requirements for the data that are used in business operations, and provided or received in data exchanges. The partner metadata in the form of the FGDC Metadata Content Standard could also then be submitted to and used by the clearinghouse for search, query, and location of data sets (FGDC, 1995, March 24). Additional partner requirements included relationships from record boundary to hydrography and transportation features, significant location as a coordinated point, attributing corners with Geographic Coordinate Database codes, and Federal Information Processing Standard codes (Bureau of Land Management 1997).
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. In terms of developing DNR projects, the Automated Tract Book Project and the Aquatic Land Ownership Project are included in the development data model. The complexity of this approach is apparent, and some of the logical modeling was reworked in physical prototyping.
The structure of relationships between Parcel, Parcel Transaction, Transferred Right, and Agent was changed from the Cadastral Data Content Standard to allow for collecting initial data. The structure of the Cadastral Data Content Standard required transaction documentation for every parcel. In most cases, GIS databases do not have land transaction data stored that would document a clear line of title. Without modification, the standard would not be able to accept data converted from existing databases. Therefore, the relationships were altered in the Washington model for Parcel Transaction to go between Parcel, Agent, and Document (Source Link) as a three-way relationship. Transferred Right was attached directly to Parcel. Some of the data provided to the Cadastral Framework database may not be thoroughly documented, but publishing the information without source documents over the Internet allows challenges to surface and forces recovery of transaction documentation. The accuracy of ownership and encumbrance information will increase over time.
Several things were learned from the September 1998 National Spatial Data Infrastructure meeting. The data content standards are the minimally attributed set of data necessary to conduct the business of an FGDC theme. Extension of the data content standard should usually be limited to the business proprietary database, not the common partner database. However, data content standards for governmental unit, geodetic control, hydrography, and transportation have not been developed yet. Theme extension from the perspective of the Cadastral Data Content Standard is the only option currently available.
Prototyping and Physical Data 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 supertype/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 using the ArcPlot SDE utilities. These layers can be merged back together into a region coverage for editing.
Metadata developed for the Washington Cadastral Framework Database have been on the Washington Clearinghouse Node of the Federal Geospatial Data Clearinghouse since August 1998 (Washington Cadastral Framework Partnership 1998b). The clearinghouse metadata is a brief summary of the whole cadastral data set. Metadata for individual layers of the Washington Cadastral Framework Database are developed separately and are available from the project Web site (Washington Cadastral Framework Partnership 1998a). The intent is to have the most general metadata searchable at the national level, then more detailed metadata available at the state level.
ESRI's ArcView Internet Map Server (IMS) 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. The default only returned query results from the first active theme. 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 .
Currently, the legal area descriptions for Public Land Survey townships and sections are available to Framework Partners by county or statewide. Boundaries, corner points, state ownership, other public ownership, government units, and administrative subdivisions should be available by the date of publication. 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. (Washington Cadastral Framework Partnership 1998a.)
FGDC Cadastral Data Transfer Standard
The FGDC Cadastral Data Transfer Standard is in terms of an Arc/Info regions export coverage. It is basically the same as the Cadastral Data Content Standards, except that only PLS legal area descriptions are represented at this time. (FGDC, Cadastral Subcommittee 1998a.) The data transfer standard has no coding scheme and may be difficult to use for data exchange.
Washington cadastral framework partners decided that validation of data being contributed is required for integration of partner data into the framework database. In order to increase the speed and accuracy of update transactions, values for many attributes are coded. Text string searches, which take time and can be inaccurate, are minimized.
The focus of the data integration process is to facilitate accurate and timely data integration to the Framework database while minimizing the effort that has to be spent by the Integrator on validating data and resolving errors. Additional cadastral data transfer standards will be developed to allow exchange of data over the Internet using shape files, export coverages, and AutoCAD formats. The roles in the database integration process are data developers, data providers, database stewards, database integrators, database administrators, and data users. Data developers create proprietary databases which have data that could be shared in a framework database. Data providers are certified to provide data updates to the framework database. Data stewards are the business experts familiar with cadastral data who have been designated to certify data sets for integration, and resolve database conflicts. Data users are the public and private agencies who conduct cadastral business; these will be targeted for cadastral framework publicity and information. Database integrators review the results of integration validation and respond to problems and conflicts. Database administrators support the framework database operations, backup, and recovery.
The developer, data sets, and metadata must be certified by the database stewards for updating the database. The developer must build a procedure to convert data from the proprietary database to a data transfer standard with the assistance of the database integrator. Cadastral framework data sets include legal area descriptions, boundaries, corners, geodetic control points, parcel transactions, record documents, governmental units, and administrative areas. Data developers who are just creating or revising their proprietary databases will have the opportunity to adopt the FGDC Cadastral Data Content Standard to make framework transactions easier.
Once the developer has been certified as a data provider, the provider can check data out of the database, make updates, and check data back into a staging area. Check-out is limited to the providers jurisdiction and authority. Updates are to be on a thirty day cycle; check-outs for updates that are expired will be canceled. The framework integration application will validate data by transaction, authority, jurisdiction, and history. Transactions are validated by the conformance with the data structure. Authority is validated by the data sets which have been certified for the provider. For example, the provider must have a land surveyor make updates on legal area descriptions, boundaries, or corners. Jurisdiction is validated by geographic area. History is validated against the existing records on the database. The database integrator must then review the validation reports and plots to decide whether to accept the database update from the staging area. If there are database integration problems, such as formatting or coding problems, then the integrator will just return the update to the provider with the validation report. If there are data conflicts in the update, such as accepting a different monument as the representation of a corner, then the integrator must consult with the data steward and the provider to determine the intent of the update and make a decision on accepting the update. Data older than that current on the database would be retired on check-in (Hair et al 1997).
The next steps are to reexamine the business events and processes. Events include data change, data integration problem, data conflict, database failure, and data requirement change. Processes include data development, location of developed data through clearinghouse indexing, data provider certification, data editing, database update notification, database maintenance, database integration, database integration problem resolution, database conflict resolution, database backup and recovery, and database change control. The procedural response to each event, and the details of each process are being finalized with partners.
Data stewards will draft quality control standards for data certification. The standards will determine the authority and jurisdiction of data providers. Data stewards will also examine the data conflict situations,. The data parameters identifying conflict situations will have to be developed to minimize database integrator intervention. The data stewards will have to work through conflict resolution processes for handling each situation.
The project will construct the whole update and integration application. Database administrators will continue to evaluate data formats for editing and exchange. Partners will integrate framework data within the pilot geographic area (Snohomish County). The database integrator (DNR) will maintain the framework database and distribute on a continual basis. The project will evaluate cadastral data editing packages, then develop or acquire an edit environment. The developers will build an Internet check-in/check-out staging area and start developing tools and utilities for data integration, problem resolution, and conflict resolution.
The partnership will determine how to financially support the stewardship, integration, maintenance, and distribution of the framework database. Financial incentives for getting rural counties started on the framework database will be addressed. Additional private organizations will be encouraged to participate in the cadastral framework, in particular surveying firms doing work for rural counties.
The Washington State Cadastral Framework Project will continue to provide assistance to other state cadastral framework projects. Additionally, coordination will continue with other Washington framework projects on government unit, transportation, and hydrography framework theme development. The formation of a technical coordination group is being considered by the Washington Framework Management Group.
The Washington Cadastral Framework Demonstration Project is an ambitious effort that tests an inter-organizational partnership approach to create, manage, and distribute commonly needed cadastral data. The 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 the start of sustained cadastral data maintenance by multiple partner organizations. 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.
The authors wish to thank the members of the Washington Department of Natural Resources, the Washington Cadastral Framework Project Partnership, the Washington Framework Management Group, the Washington Geographic Information Council, the Federal Geographic Data Committee, and the Cadastral Subcommittee for their assistance with this project. Supported by the U.S. Geological Survey, Department of the Interior, under assistance award No. 98HQAG2162.
This manuscript is submitted for publication with the understanding that the United States Government is authorized to reproduce and distribute reprints for governmental use.
The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U.S. Government.
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