Cadastral Principles

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Cadastral Principles
Grenville Barnes
TCI Workshop 17 October 2007
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Content

• Purpose
• Cadastral vs Geodetic points
• Cadastral System
• Boundary Types
• Cadastral Surveying Process
• Cadastral Evidence
• Heterogeneity Example
• Professional Trends

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PURPOSE OF CADASTRAL SURVEYING

• Demarcate and Identify Boundaries
• Collect Evidence to Perpetuate Boundary Location
  to Promote Security of Tenure
• Obtain Data to Represent Boundaries in an
  Abstract Form (graphical and mathematic evidence)

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Specific Purpose of a Cadastral System

•      Where is the parcel?
•     What size (area) is the parcel?
•      What are the dimensions of the parcel
  boundaries?
•      What constitutes the parcel boundaries?
•    What is the unique identifier of the parcel

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Multipurpose Land Information System
Owners/Lessees
Registry Information
Source of rights
Restrictions
Encumbrances
Information Layers
Parcel Identifier

• natural resources
• infrastructure
• socio-economic

Cadastral Database
Survey Records
Geodetic Infrastructure
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Components of a Cadastral System
Spatial Geo-reference Framework
Cadastral Survey
Cadastre
INFRASTRUCTURE
MEASUREMENT
MANAGEMENT
The spatial geo-reference framework provides a
common reference system for the integration of
tenure and other land information.
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Cadastral vs Geodetic Points

• Location of geodetic points is a question of
  mathematics (coords may vary if datum changes or
  through readjustment)
• Location of cadastral points (parcel corners) is
  defined by law and evidence (location depends on
  interpretation of cadastral evidence, especially
  physical evidence
• Cadastral surveying is the process of defining
  and describing boundary evidence

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Fixed vs General Boundaries

• Fixed - corners/bendpoints are beaconed and
  boundary is the invisible line in between the
  beacons
• General a physical feature (hedge, wall, fence,
  etc.) is accepted as the boundary and mapped

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Point Typology

• Parcel corner beacons
• Indicatory beacons
• Control stations (e.g. traverse) connection to
  geodetic network
• Geodetic Control Points

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Cadastral Surveying Process

• Prior to fieldwork acquire cadastral data on
  previous surveys of the parcel and adjoining
  parcels (Reg. 10)
• Search for original beacons in field
• Survey in found monuments and permanently
  demarcate control stations (link to geodetic
  control)
• Compare found evidence with previous survey
  evidence (measurements, beacons, etc)
• Recompute and Replace missing beacons
• Document survey (report, coord list, comps,
  fieldbook, etc)

How does this change with use of GPS technology??
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Cadastral Surveying Challenge

• Cadastral boundaries are surveyed by different
  surveyors at different times to different
  specifications using different equipment..
• As a result they are a heterogeneous
• set of points
• Can GPS promote homogeneity?

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Cadastral Data as Evidence
Physical
beacons
witness marks
improvements
fences
area
coordinates
distances
Survey plan
angles
Index map
Mathematical/ Measurement
Graphical
Verbal
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Hierarchy of Cadastral Evidence
Physical Parcel
beacons
REALITY
Beacon description
Measurements
Field Notes/ Observations
Computations
Increasing weight of evidence
Coordinates
Area Calculation
Survey Plan
INCREASING ABSTRACTION
Index Map
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(200)
B
A
2
(150)
(150)
C
D
(200)
ORIGINAL (PARENT) PARCEL (Assume that
coordinates are fixed in database)
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(200)
B
198
A
26
27
(150)
(150)
Rem of 2
147
28
C
D
(200)
Owner of 2 requests three 50x100 parcels be
subdivided out of parent parcel
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(200)
B
A
26
99
49
27
99
49
(150)
(150)
28
99
Rem of 2
49
C
D
(200)
Surveyor finds A, B and C and several other
original beacons and proves that these are
original, undisturbed and consistent What
happens to the fixed coordinates in the
database??? Measurements are never exact they
contain systematic and random errors
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FUNDAMENTAL PRINCIPLES

• Equipment is calibrated prior to first use and
  periodically after that (e.g. 6 monthly)
• Measurement to property corners are checked with
  independent measurements
• The original survey provides a definitive
  description of the parcel boundaries
• Relocation of parcel boundaries is determined by
  a consideration of various evidence

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Terrain/Access
Open
Thick bush
Good
Low
Least Expensive
Cadastral Field Evidence
Land Value
More expensive
Most Expensive
High
Poor
Cadastral Record Evidence
Good
Poor
Matrix of Rural Survey Cost Components
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Surveying Professional Trends

• Develop thin Survey/Mapping Department that
  deals primarily with Quality Control and Project
  Management
• Contract out surveys to private sector
• Government responsible for geodetic
  infrastructure
• Emergence of surveying profession (private and
  public)

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Cadastre 2014 FIG 20 year Vision

• Show the complete legal situation of land,
  including public rights and restrictions.
• Separation between maps and registers will
  be abolished.
• Cadastral mapping will be defunct it will be
  replaced by modeling.
• Paper pencil cadastre will be replaced by
  modern technology.
• Cadastre will be highly privatized with public
  and private sector working closely together.
• Procedures for definition of private and public
  land objects will be identical.

http//www.fig.net/cadastre2014/
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Reg. 36 (2)(c)

• A surveyor shall not use a loop traverse closing
  on his starting point if it is practicable to
  traverse between two previously fixed stations.