Managing a Cadastral SDI Framework Built from Boundary Data

Managing a Cadastral SDI Managing a Cadastral SDI Framework Built from Framework Built from

Boundary DataBoundary Data

Michael ElfickMichael ElfickTim HodsonTim HodsonCurt WilkinsonCurt Wilkinson

AgendaAgenda

Introduction – Current situationIntroduction – Current situationBackground and Design ConceptsBackground and Design ConceptsData ModelData ModelWorkflowWorkflow

The influence of GPSThe influence of GPS

GPS enabled systems will be GPS enabled systems will be everywhereeverywhere

To make GPS truly valuable, GIS To make GPS truly valuable, GIS must supply underlying mapping must supply underlying mapping informationinformation

This information must be accurateThis information must be accurateAccurate data greatly extends the Accurate data greatly extends the

usefulness of GISusefulness of GIS

Typical errors in digitized dataTypical errors in digitized data

GoalGoalA simple system to create and manage A simple system to create and manage

spatially accurate cadastral geometry in a spatially accurate cadastral geometry in a GIS.GIS.

The system must be extendable and:The system must be extendable and:

Follow survey methodsFollow survey methods

Be able to improve existing datasetsBe able to improve existing datasets

Maintain spatial relationships between the Maintain spatial relationships between the Cadastre and associated GIS layers.Cadastre and associated GIS layers.

Scope of TechnologyScope of Technology

Focus on cadastral geometryFocus on cadastral geometrynot a full cadastral systemnot a full cadastral system

A key part of a GIS systemA key part of a GIS systemDesigned to be an extendable Designed to be an extendable

platformplatformFor land records and cadastreFor land records and cadastreComplements a civil and survey systemComplements a civil and survey system

Cadastral FabricCadastral Fabric

The fabric is a The fabric is a continuous surfacecontinuous surface of of connected parcelsconnected parcels

It is also a dimensioned It is also a dimensioned boundary networkboundary network Has an Has an explicit topologyexplicit topology, defined by , defined by

common parcel corners and neighborscommon parcel corners and neighbors Topology is inherent in the model, and is Topology is inherent in the model, and is

defined and enforced during data entrydefined and enforced during data entry

Survey MeasurementsSurvey Measurements

In the past, measures of bearing and In the past, measures of bearing and distance were much easier than fixing a distance were much easier than fixing a location on the surface of the earthlocation on the surface of the earth

Land surveys are parcel dimensions, Land surveys are parcel dimensions, with known error in the measureswith known error in the measures

Parcels are also defined by their relation Parcels are also defined by their relation to other parcels to other parcels

So, measures and connections were known, but true coordinates were not

From From MeasuresMeasures to to CoordinatesCoordinates

We need accurate coordinates for the We need accurate coordinates for the fabricfabric and associated GIS layers and associated GIS layers

Accurate coordinates are close to the Accurate coordinates are close to the truetrue coordinates coordinatesImplies there is a real object (not always)Implies there is a real object (not always)and we know how close (statistic of error)and we know how close (statistic of error)

For Instance, Control Points have:For Instance, Control Points have:A physical location (monument)A physical location (monument)Error information (level of confidence)Error information (level of confidence)

Central ConceptsCentral Concepts Often, associated GIS layers are created Often, associated GIS layers are created

and maintained in context with the and maintained in context with the CadastreCadastre

An accurate Cadastre can serve as the An accurate Cadastre can serve as the ‘control’ for the rest of the GIS‘control’ for the rest of the GIS

If we capture the shifts in coordinates of If we capture the shifts in coordinates of the Cadastre, we can then adjust the the Cadastre, we can then adjust the associated layers and maintain spatial associated layers and maintain spatial relationshipsrelationships

The result is more accurate coordinates all The result is more accurate coordinates all aroundaround

Central Design ConceptCentral Design Concept

Differentiation of Source information Differentiation of Source information from derived informationfrom derived information

ESR Shapes Coordinates Measurements

Derived from Coordinates

Computed from LSA – held by Points

From Survey or Records – held by the Line

Editable by standard GIS

Edited only by Cadastral Editor

Parcels are the ‘Parcels are the ‘unit of workunit of work’’Create & edit Create & edit parcelsparcelsJoin Join parcelsparcels to the fabric to the fabric

Control points ‘Control points ‘fix’ fix’ the fabricthe fabricConnected (and historic) parcels have Connected (and historic) parcels have

redundancyredundancy of measurementsof measurementsMultiple measurements & control Multiple measurements & control

points processed in a points processed in a least squares least squares adjustmentadjustment

Fabric FundamentalsFabric Fundamentals

Parcel ModelParcel Model

Parcels are represented by :Parcels are represented by :parcel lineparcel line features, features, parcel pointparcel point features, and features, and parcel polygonparcel polygon features, features, referred to in aggregate as referred to in aggregate as parcel featuresparcel features

Survey Database feature classParcels

Data typeField nameAllow nulls

OBJECTID Object ID SHAPE Geometry YesJoined Short integer No

ParcelName String NoPlanID Long integer No

ParcelType Short integer NoStatedArea Double YesCompiled Short integer No

TrueMidBrg Short integer NoHistorical Short integer No

SytemStartDate Date NoSystemEndDate Date NoLegalStartDate Date YesLegalEndDate Date Yes

SHAPE_Length Double YesSHAPE_Area Double Yes

CentroidX Double YesCentroidY Double Yes

AccuracyID Long integer No

Survey Database feature classLines



ParcelID Long integer NoSequence Long integer YesFromPoint Long integer No

ToPoint Long integer NoBearing Double YesDistance Double YesLineType Short integer NoRadius Double Yes

ArcDistance Double YesDelta Double Yes

CenterPoint Long integer YesHistorical Short integer No

SHAPE_Length Double YesRadialBearing Double Yes

TangentBearing Double YesEntryParameters Short integer No

AccuracyID Long integer Yes

Survey Database feature classPoints



PointCode String YesPointName String YesHistorical Short integer NoRemarks String Yes

Contourable Short integer NoSystemStartDate Date YesSystemEndDate Date YesLegalStartDate Date YesLegalEndDate Date Yes

Parcel

Parcel ModelParcel Model

Parcels are defined by Parcels are defined by non-spatial datanon-spatial data, and , and Parcels have Parcels have spatial dataspatial data – dimensions on lines – dimensions on lines

Survey Database feature classParcels




















Relationship class

One to many

Parcel_Lines
















Relationship class

One to many

Lines_Points

Lines have Lines have geometrygeometry defined by defined by dimensionsdimensions and by and by pointspoints

Model of a ParcelModel of a Parcel

Points & Control PointsPoints & Control Points






Survey Database feature classControlPoints


OBJECTID Object ID SHAPE Geometry Yes

X Double YesY Double YesZ Double Yes

Name String NoPointID Long integer Yes

AccuracyXY Double YesAccuracyZ Double Yes

CreatedDate Date YesActive Short integer Yes

GridFactor Double YesPointType Short integer No

Relationship class

One to One

Points_ControlPoints

A A control pointcontrol point is an special type of is an special type of parcel parcel pointpoint, giving that point an , giving that point an enhanced statusenhanced status

PlansPlans

Plans are used to represent a collection of Plans are used to represent a collection of information about a legal land documentinformation about a legal land document

Survey Database TablePlans


OBJECTID Object ID PlanName String No

AngularUnits Short integer YesDistanceUnits Short integer Yes

Surveyor String YesCompany String Yes

SurveyDate String YesModificationDate Date Yes

CoordinateSystem String YesStatus Short integer No

Coded value domainPlan StatusDescription

Field typeSplit policy

Merge policy

Status of the PlanShort integerDefault valueDefault value

DescriptionCode

0 0 - Tentative

1 1 - Provisional

2 2 - Approved

3 3 - Registered

Plans - ConceptsPlans - Concepts Most Parcels are associated with a Most Parcels are associated with a planplan

andand Jobs are often based on PlansJobs are often based on Plans Plans and all associated parcels can be Plans and all associated parcels can be

recovered from the Cadastral Fabric recovered from the Cadastral Fabric Plans hold the metadata for parcels (go Plans hold the metadata for parcels (go

back to legal document of origin)back to legal document of origin) You can extend the Plan concept to fit You can extend the Plan concept to fit

your organization, for example:your organization, for example: you can add to the schema for other sorts of you can add to the schema for other sorts of

metadata about the documentmetadata about the document

Data ModelData Model

Plans ModelPlans ModelSurvey Database TablePlans


OBJECTID Object ID PlanName String No

AngularUnits Short integer YesDistanceUnits Short integer Yes

Surveyor String YesCompany String Yes

SurveyDate String YesModificationDate Date Yes

CoordinateSystem String YesStatus Short integer No

Coded value domainPlan StatusDescription

Field typeSplit policy

Merge policy

Status of the PlanShort integerDefault valueDefault value

DescriptionCode

0 0 - Tentative

1 1 - Provisional

2 2 - Approved

3 3 - Registered

Survey Database feature class










Parcels

Relationship class

One to many

Plan_Parcel

Status manages the life-cycle of the Plan

History - ConceptsHistory - Concepts Parcels updated with new record information Parcels updated with new record information

are never deleted from the Fabric, they are are never deleted from the Fabric, they are simply marked as Historicsimply marked as Historic

4 different types of historic information 4 different types of historic information maintained:maintained: State of the Cadastre on a particular date State of the Cadastre on a particular date State of the Fabric on a particular date State of the Fabric on a particular date Lineage of a Lineage of a ParcelParcel History of Adjustments to the Cadastral History of Adjustments to the Cadastral

FabricFabric

1 2 36 644

2 74

1985 1994 2000

CustomisationCustomisation

This can start with adding new attributes This can start with adding new attributes (fields) to the Cadastral Fabric Tables(fields) to the Cadastral Fabric Tables

The Cadastral Editor can be used to edit The Cadastral Editor can be used to edit these attributes via the Property these attributes via the Property InspectorInspector

The Cadastral Editor UI is written using The Cadastral Editor UI is written using ArcObjects components, overlying an ArcObjects components, overlying an editing engineediting engine

WorkflowWorkflow

System IntegrationSystem Integration

Cadastral fabric tables can have Cadastral fabric tables can have relationships to other geodatabase tables relationships to other geodatabase tables via relationship classesvia relationship classes

So other systems, like a text based title So other systems, like a text based title management database, can be linked to management database, can be linked to the cadastral geometry of the fabricthe cadastral geometry of the fabric

WorkflowWorkflow

Editing WorkflowEditing Workflow

CadastralFabric

CreateJob

Select Parcels

StartEditing

AdjustSave orCommit

Lock

WorkflowWorkflow

Jobs – “Work-Orders”Jobs – “Work-Orders” A Job is a “A Job is a “work-orderwork-order” for creating, ” for creating,

modifying or adjusting one or more modifying or adjusting one or more parcels. For instance:parcels. For instance:Entering a parcel subdivisionEntering a parcel subdivisionEntering control pointsEntering control pointsAdjustmentAdjustment

WorkflowWorkflow

Survey Database TableJob


OBJECTID Object ID Name String No

Description String YesLocked Short integer No

LockedDate Date NoUpdateDate Date Yes

Jobs can be Jobs can be savedsaved, or , or committedcommitted Jobs can be open for any length of time Jobs can be open for any length of time

Locked ParcelsLocked Parcels A job may lock parcels, no other job can edit A job may lock parcels, no other job can edit

the parcel attributes or dimensionsthe parcel attributes or dimensions Parcel Points are never lockedParcel Points are never locked This allows LSA adjustment while jobs are This allows LSA adjustment while jobs are

openopen If not locked, standard reconcile will detect If not locked, standard reconcile will detect

conflictsconflicts

Survey Database TableJob


OBJECTID Object ID Name String No

Description String YesLocked Short integer No

LockedDate Date NoUpdateDate Date Yes

Relationship class

One to many

JobLockIDs_Jobs

TableJobLockIDs


OBJECTID Object ID JobID Long integer No

ObjectType Short integer NoOIDLock Long integer No

LockMethod Long integer Yes

Data ModelData Model

Parcel EditingParcel Editing The ‘unit of work’The ‘unit of work’ Parcels are created Parcels are created

by entering a loop by entering a loop traverse of the traverse of the parcel boundaryparcel boundary

Parcel closureParcel closure report is a report is a first level first level Q/A checkQ/A check

WorkflowWorkflow

First Level QA check

Parcel Join - ConceptsParcel Join - Concepts

Parcel Joining Parcel Joining enforcesenforces the the topologicaltopological model relationshipsmodel relationships between parcels between parcels

Join is an interactive ‘point and click’ UIJoin is an interactive ‘point and click’ UIMatch shared pointsMatch shared pointsAutomatic scale and rotate Automatic scale and rotate Auto-join utilityAuto-join utility

Second level QA checkSecond level QA check provided by the provided by the transformation residuals during a jointransformation residuals during a join

WorkflowWorkflow

Parcel JoinParcel Join

Second Level QA check

JoinJoin Joining is the easiest and fastest way to Joining is the easiest and fastest way to

build the Fabricbuild the Fabric Join process ensures fit to the FabricJoin process ensures fit to the Fabric

No slivers possibleNo slivers possible No accidental overlapsNo accidental overlaps Automatically handles translation, scale, Automatically handles translation, scale,

rotation from local reference systemrotation from local reference system

Each newly joined parcel adds valuable Each newly joined parcel adds valuable information that can be used in future information that can be used in future least squares adjustment jobsleast squares adjustment jobs

Least Squares AdjustmentLeast Squares Adjustment

Fabric + Control +LSA = Good CoordinatesFabric + Control +LSA = Good Coordinates Preparation of the data is half the workPreparation of the data is half the work

The fabric model and the software does thisThe fabric model and the software does this LSA does more than improve the LSA does more than improve the

coordinatescoordinates Shows where control is neededShows where control is needed Finds errors in the data (eg. incorrectly entered Finds errors in the data (eg. incorrectly entered

measurements…)measurements…) Extensive Reports on analysis of the dataExtensive Reports on analysis of the data

Works Works only on the coordinatesonly on the coordinates, never , never changes the original measurement valueschanges the original measurement values

Job AdjustmentJob Adjustment Once the Control Once the Control

has been tested, has been tested, job adjustment is job adjustment is easyeasy

Set tolerancesSet tolerances Select Select

constraintsconstraintsStraight linesStraight linesLine pointsLine points

WorkflowWorkflow

Job Commit (close-out)Job Commit (close-out) Before a change is inserted into the Before a change is inserted into the

Cadastral Fabric the system does Cadastral Fabric the system does integrity checks :integrity checks : Tests of bounding parcel coordinates Tests of bounding parcel coordinates Notify if need to readjustNotify if need to readjust If parcels were not locked, then reconcileIf parcels were not locked, then reconcile

On commit, the system:On commit, the system: Calculates adjustment vectorsCalculates adjustment vectors Updates job, history…Updates job, history… Releases locks on the parcelsReleases locks on the parcels

WorkflowWorkflow

Associated Feature ClassesAssociated Feature Classes On commit, the transaction manager On commit, the transaction manager

creates a set of Adjustment Vectorscreates a set of Adjustment Vectors Each point’s coordinate residual provides a Each point’s coordinate residual provides a

vector that may be used on the GIS layersvector that may be used on the GIS layers Vector sets are stored as a history of Vector sets are stored as a history of

coordinate shifts based on each least sq. coordinate shifts based on each least sq. adjustmentadjustment

GIS Layers can be updated using the GIS Layers can be updated using the Adjustment VectorsAdjustment Vectors You decide when to make a GIS layer update You decide when to make a GIS layer update

to the Cadastral Fabricto the Cadastral Fabric This is possible because Cadastral Fabric This is possible because Cadastral Fabric

maintains the adjustment “history” of each maintains the adjustment “history” of each layerlayer

WorkflowWorkflow

GIS Layers AdjustmentGIS Layers AdjustmentWorkflowWorkflow

GIS Layers AdjustmentGIS Layers AdjustmentWorkflowWorkflow

SUMMARYSUMMARY

ArcGIS has been extended for cadastre dataArcGIS has been extended for cadastre data Improve existing data, regardless of qualityImprove existing data, regardless of quality It uses survey methodsIt uses survey methods Can follow a job workflow, and keep historyCan follow a job workflow, and keep history Applies cadastral adjustments to feature Applies cadastral adjustments to feature

classesclasses Is an easily extended and customized systemIs an easily extended and customized system It supports ‘remote’ editingIt supports ‘remote’ editing It supports pessimistic lockingIt supports pessimistic locking Can be scaled to very large datasetsCan be scaled to very large datasets

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Managing a Cadastral SDI Framework Built from Boundary Data