The Keys to a Successful Transition to the Parcel Editing Solution (the Parcel Fabric)

Having performed several dozen migrations for large and small clients across the United States with everything from hundreds of CAD files to topologically valid feature classes already in SDE and provided training to hundreds of students across the United States about the Parcel Fabric technology in the ESRI ArcGIS Parcel Editing Solution, I have often been asked what differentiates those organizations that successfully transition into the ArcGIS Parcel Editing Solution from those that struggle during the transition.  While it is hard to pinpoint any single characteristic of the successful transitions, but I can say there are certain traits that help. 

What Should my Source Data Look Like?

First, success with the transition is less technology-driven and more personnel-driven.  While having feature classes with good valid topology does help - the technical challenges of converting data from any source is fairly easily overcome. There are ways to ensure the source data that will be used to construct the various polygon types will migrate correctly, but these tools all work against the features while they are still stored as topology feature classes.  There are several add-ins to help and there is a multitude of geoprocessing tools to "fix" the source data prior to the migration and any good ESRI business partner that is knowledgable about the migration clearly knows what to look out for and what should be done with the data to ensure the migration is successful. However, it is not the data that makes the transition successful or not, it is the personnel responsible for the everyday maintenance that will determine how quickly the successful transition occurs

Should I Do the Data Migration Myself?

Several times Panda Consulting has been contacted by organizations that are either struggling to migrate their data, or, have migrated their data and struggling as a result of that migration. The migration of your source data into the Parcel Fabric is not trivial and it is only after several learning attempts that one can fully understand how to make a successful migration. There is everything from correcting incorrect topology - to "fixing" curves that have been "exploded" through earlier migration in and out of shapefiles - to creating valid road polygons to ensure the parcels do not experience coordinate creep - to fully ensuring all attribution is correctly migrated. It is important to have the help of someone who has made this migration before.  I liken this to working on your car, while it is possible for you to perform many maintenance tasks with your vehicle, when it comes time to perform major maintenance tasks, it is time better spent by having an expert perform these tasks for you, especially since you should only need to perform this migration once.  

The Impact of Personnel

It is the flexibility / adaptability of the personnel, the "mappers",  to transition the way in which they think about what they do and the products they create that will determine how well the transition occurs. If the people that will be working with the data every day are open to the new tools and the new ways to look at the data, they can quickly make the transition. I have seen this transition from initial exposure to the Parcel Editing Solution to being "comfortable" with the approaches, tools and confident in the ability to effectively manage the data range from 30 days to 9 months, with 6 months being the average amount of time it takes for the cadastralists to be completely comfortable with the transition.  

An early indication of the flexibility is how comfortable the mappers are in having their data appear differently in the ArcMap map document. If they can quickly adapt to viewing the data using the default table of contents when loading the Parcel Fabric, even with minor "tweaks", the faster they can recognize that the quality of the data is more important that then way it looks.  Within the Parcel Editing Solution, they data is presented one way for efficiency in editing and another way for publication of data and the ability to recognize this new way of looking at the data is critical for the successful transition.

The Tools

The Parcel Fabric technology used in the Parcel Editing Solution uses "composite" features to represent the parcels.  Since each composite feature consists of a single polygon, all lines associated with that polygon, ties to corner points that are used to join parcel corners together and links to control points (in addition to source document information, i.e. "plans"), the standard editing tools used to maintain simple feature classes do not work against these composite features.  Instead, there are a new set of Parcel Fabric editing tools that manipulate the composite features. These new Parcel Fabric editing tools, because they work against multiple features at the same time are actually more efficient that the standard editing tools.  How adaptable the mappers are in making the transition also differentiates the successful transition from this that struggle.  It is ironic that sometimes those clients that have never used ArcGIS standard editing tools, nor done any parcel mapping in ArcMap can actually make the transition faster than those clients that have been using COGO and advanced parcel mapping techniques for years.

Continued Support

Due to the extended time and continued exposure to the tools before being completely comfortable, it is important that new users have access to continued support.  This support can be either the Land Records Meetup provided by ESRI that meets on a regular basis, the Virtual Panda services offered by Panda Consulting or the bi-weekly Panda Parcel Fabric Forum, an online meeting for people who wish to learn more about the Parcel Editing Solution and share best practices for using the tools. The Panda Parcel Fabric Forum is available by invitation only so, please contact us if you wish to be invited.

From Cadastralists to Curators

The long term impact of transitioning into the Parcel Editing Solution is a change in the focus of the cadastralist from performing cartography, i.e. creating "maps", into performing digital curation of land records data. There is less focus on how the map looks and a greater focus on making the data correct. Many little things that could be "fudged" to make the map look valid become exposed during the migration of the data and become visible inside the Parcel Editing Solution. Those mappers that can make that transition have proven to be the most successful in successfully adopting and taking advantage of the benefits of the ArcGIS Parcel Editing Solution.

The Parcel Data Model - The Partitioning Types

(As a result of input from Nancy Von Meyer, (see below), I have revised some of the verbiage in this posting.)

During the next two weeks we will explore the Parcel Data Model used by the ESRI Parcel Fabric Land Records maintenance solution. This week we look into the polygon types that define the partitioning of lands into smaller divisions that can be sold and next week we will look at the polygon types that are used to store and maintain information on various forms of land ownership and obligation.

The Parcel Data Model used by the ESRI Parcel Fabric is described in detail in the "GIS and Land Records" book by Nancy Von Meyer (ISBN-13: 978-1589480773). This data model provides the most comprehensive data structure focussed on Land Records we have seen to date and we highly recommend this data model to everyone involved in mapping Land Records. 

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Two Distinct Classes of Information

Overall, the data model breaks information into two distinct categories: the information that serves to partition lands (Public and Private) and the various types of land ownership (Tax Parcels, Fee Simple Ownership, Encumbrances and Separated Rights.)

The following discussion of Public and Private divisions is not intended to be exhaustive, or even thorough.  It is intended to be an introduction to the concepts and additional information can be found here.

Within each of these classes, information is split into discrete layers or "Types" of polygons.

Partitioning Classes

The Partitioning classes are divided between Federal Subdivisions of Public Lands, commonly referred to as the Public Lands Survey System (PLSS) or Rectangular Survey System and Private Subdivisions in which private landowners divide their lands for sale to individuals.

Please note that I am purposely using the word "partitioning" instead of "subdivision" because there are so many meanings and implicit baggage that comes along when we use the word "subdivision". Recognize, the word "partition" is intended to define lands that are owned by an entity that is dividing up the lands so they may sell off portions of it to other individuals.

Federal Subdivisions of Public Lands

The polygon "Types" related to the Federal Partitions directly reflect the components of the Original Surveys from which the Federal lands were sold to private citizens through patents or deeds. These "Types" also reflect in many ways the order in which the lands are identified.

Type 1 - PLSS  Townships

The PLSS Townships

The PLSS Townships

Type 1 polygons reflect the first division of Public lands from which all other divisions are derived. These "Townships", depending on the data of survey and instruction provided to the original surveyors may be anywhere from 6 miles square (the most common) to 7 miles square and several other variations. They are identified by their sequence from the Initial Point in the Principal Meridian and are referenced in a North - South direction as lying North or South of the Base Line and East or West of the Principal Meridian.

All measurements involved in the PLSS are performed using the "Gunter's Chain", generally equivalent to 66 feet in length. 

Type 2 - PLSS Sections

Section Numbering and Sequence in which section lines are surveyed to subdivide Townships

Section Numbering and Sequence in which section lines are surveyed to subdivide Townships

Type 2 polygons reflect the second division of Public lands into smaller polygons approximately one mile by one mile in size. The sections are constructed after the Township perimeter has been established and monuments have been placed at defined locations by the original surveyor. They are numbered beginning with "one" at the Northeast corner of he Township and numbered sequentially in a snake pattern alternating east to west then southerly until all sections are identified. The "normal" section of land consists of approximately 640 acres.



Type 3 - Quarter Sections

Division of sections into Quarter Sections

Division of sections into Quarter Sections

Type 3 polygons reflect the third division of Public lands into smaller polygons by connecting straight lines between the monuments established by the original surveyor at the North, South, East and West lines of the sections.  These are commonly referenced as "Quarter Sections".. The goal in establishing these quarter sections was to create as many aliquot portions of land containing as close to 160 acres of land as possible.  If, however, the sections measured longer or shorter on the northern or western tiers of sections with the Township, smaller aliquot portions are created.  These aliquot portions include the Government Lots around sovereign lands, previous land grants prior to the acquisition of the lands by the US Government or other situations. 

There is a general misunderstanding of his process within the mapping community that believes that quarter sections are derived by dividing the Section into fourths - This is incorrect.

Type 4 - Special Surveys

Special Surveys

Special Surveys

Type 4 polygons reflect the fourth division of Public lands and encompasses those situations in which special surveys were required. According to the BLM, these are non rectangular components of the PLSS including: Meandered Water, Corners and Conflicted Areas (known areas of gaps or overlaps between Townships or state boundaries). 


Private Partitions

The next two polygon "Types" describe the partitioning of lands by private landowners into smaller areas for sale to others. Because almost all lands in the United States are derived from the original public ownership managed by the Federal government, the exact location and definition of these private partitions (subdivisions) is completely dependent upon the quality of the location of the Public polygon types.

Type 5 - Simultaneous Conveyances (Subdivisions and Condominiums)

Private Subdivision

Private Subdivision

Type 5 polygons reflect the overall extent of privately owned lands that are partitioned into groups of smaller lots of units for sale. As with the smaller divisions of the Public lands partitions, the smaller units of the Private partitions come into existence at the moment that these partitions (Subdivision Plats or Declarations of Condominiums) are approved and recorded in the public records. In other words, the smaller divisions are "simultaneously" approved and "conveyed" into existence. Since these units are created at exactly the same time, none of these smaller units are "senior" nor "junior" to the rights of any other units in the subivision. These Type 5 polygons include those divisions commonly referred to as "Subdivisions" and "Condominiums".

Type 6 - Simultaneous Conveyance Divisions (Lots, Blocks and Units)

Subdivision Lots and Tract

Subdivision Lots and Tract

 Type 6 polygons reflect the final type within the Parcel Data Model that reflects the partitioning of land for sale and does not contain any information about land ownership. This polygon type is intended to contain the smaller divisions of land with the larger Type 5 polygons (Simultaneous Conveyances).  If the larger Type 5 polygon is a traditional Subdivision, these smaller divisions might be lots, tracts, reserved areas, road tracts or parks.  If the Type 5 polygons is a Condominium, these polygons may represent the individual unit boundaries, including its 3D space, limited common ownership, or general common ownership.

Next Week:  The Parcel Data Model - Ownership Types

Be sure to check back for our Blog Post next week in which we will continue our review of the Parcel Data Model and focus on the Ownership polygon "Types", (Tax Parcels, Owneship Parcels, Encumbrances, and Separated Rights.