Manual for Cadastral Data Integration to PRS92

Purpose and objectives of PRS92 conversion

The Manual establishes standards to convert and transform cadastral data, surveys, and maps into PRS92.
The Manual ensures spatial consistency when integrating datasets into PRS92, including preparation of Control/Land Information Maps (projection maps).
The Manual governs utilization of converted datasets by other users through basic database management practices.
The Manual is designed to ensure quality, integrity, and accessibility of cadastral datasets.

Coverage and key defined terms

The Manual covers the transformation and integration of all cadastral data to PRS92.
The Manual covers database management mechanisms for the transformed datasets.
“Adjusted Coordinates” are the resulting PRS92 coordinates after applying the transformation parameters.
“Analog data” are traditional cadastral paper maps and records.
“Cadastral data” are records of cadastral and isolated surveys.
“Cadastral database” is a collection of logically related geo-referenced seamless digital vector data and raster data, organized to enable retrieval, exchange, and integration, and containing a data model for legal land objects managed by Land Management Bureau (LMB) / Land Management Services (LMS) based on existing boundary laws.
“Philippine Reference System of 1992 (PRS92)” is the national common coordinate reference system for all surveys and maps pursuant to EO 45, series of 1993, as amended by EO 321 and EO 280 (series of 2000 and 2004, respectively).
“Transformation” is the process of converting spatial datasets from one coordinate system to another.
“WGS84” is an earth-centered, earth-fixed global reference frame currently used by the Satellite-based Positioning System (SPS) for geodesy and navigation.

Cadastral data conversion process

Conversion and integration of approved cadastral data follow the process flow shown in Annex A, starting with conversion of lot corners, survey project controls, and other reference points.
The Manual makes coordinate and map conversion an initial step in creation of the digital cadastral database.
Conversion uses these data sources: lot data computation sheets, lot description sheets, field notes, monument description books, monument recovery reports, municipal or boundary index maps, project control maps, traverse computation sheets, political boundary computation sheets, and other relevant records.
Data priority for conversion is:
- (a) lot data computation sheets as the primary source;
- (b) if absent, lot description sheets;
- (c) if both are absent, reconstruct computation and description sheets using original field notes on file;
- (d) if all these sources are unavailable after exerting all efforts, resurvey individual lots/parcels under the new reference system without applying local transformation parameters.
A physical inventory must be conducted by regional land sector offices to assess completeness and quality for PRS92 integration, with results reported in the Annex B.1 to B.3 format.

Coordinate, bearing, and distance conversion

The transformation uses coordinates in Philippine Plane Coordinate System—Transverse Mercator / Luzon 1911 (PPCS-TM/Luzon 1911).
Coordinates based on the Local Plane Coordinate System (LPCS) must be converted to PPCS-TM/Luzon 1911 using procedures prescribed by the LMB for conversion between the two coordinate systems.
The encoding of project controls/reference points in PPCS-TM/Luzon 1911 must be done through keyboard entry using customized Geodetic Network Information System (GNIS) or other spreadsheet/database templates.
The encoding of individual lot/parcel lot corner Northings and Eastings in PPCS-TM/Luzon 1911 must be done through keyboard entry using customized Land Survey Data Management System (LSDMS) or other templates.
Bearings and distances computed from encoded lot corner coordinates must be checked against the technical descriptions in lot data computation sheets (LMB Form No. GSD-B-9A).
In the absence of lot data computation sheets, conversion of bearings and distances must use lot description sheets containing bearings and distances of all boundary lines and parcels.
Bearings and distances for project controls/reference points and individual lots/parcel lines must be encoded through keyboard entry using GNIS or LSDMS templates as applicable, and individual lot corner coordinates must be computed based on the lot technical descriptions.

Reconstruction, resurvey, and graphical cadastre

If lot data computation sheets and lot description sheets are missing, and original cadastral field notes remain available on file, both sets must be reconstructed using the prescribed procedures and computations.
Resurvey is required for lots with unavailable or missing records.
Resurvey must occur only after all efforts are exerted to research other sources such as the Register of Deeds/Land Registration Authority (LRA), LGUs/Assessoras Office, Court, and other agencies or individuals, and only where the affected lot is not titled/decreed.
Resurveyed lots must already be PRS92-compliant and must no longer be transformed using local transformation parameters.
For graphical cadastres, lot data computation for cadastral survey projects under the graphical cadastre system must be generated after conducting a resurvey of affected lots that are already PRS92-compliant and referenced to existing PRS92 control points.
Converted lot data computations must then be incorporated into the digital cadastral database.

Standardization, quality control, and plotting

Data conversion must follow basic encoding conventions in Annex G for uniformity and compatibility across templates.
Regional offices must implement quality control to ensure integrity of cadastral data being converted.
Errors observed in records covered by Section 4 must be properly noted for future technical/legal remedy.
Discrepancies involving untitled/undecreed parcels/lots must be corrected by the Lands Management Services of the concerned regional office.
Discrepancies involving titled/decreed parcels/lots must be corrected through court proceedings in accordance with existing LMB guidelines and procedures.
Coordinates derived from converted cadastral data must be adopted as official lot data computation and incorporated into the cadastral database.
Project controls/reference points and individual lot parcels must be plotted and projected using appropriate CAD or GIS software, and resulting digital graphics must be consolidated into digital cadastral and index maps.
A digital cadastral database must be set up and maintained to provide easy access and retrieval of converted coordinates, bearings, and distances, including available descriptions, sketches, and remarks for boundary monuments and parcels.
Cadastral, boundary index, and other maps on record must be converted and incorporated for reference, following prescribed guidelines and procedures.

Control point recovery and GPS observation

Existing reference data used for conversion must be used as reference for recovery and observation of existing control points.
Composite Survey Teams (CSTs) must undertake reconnaissance and recovery of all existing control and reference points.
CSTs must recover an additional six (6) points per adjoining municipality/cadastral survey project, located near the common boundary, to tie local transformation parameters to adjoining areas.
Recovered points must be preserved and maintained for use in subsequent surveys and in transforming other ENR datasets to PRS92.
CSTs must submit a monument recovery report with corresponding monument recovery sheets (including a monument recovery sheet format in Annex H and project control scheme template in Annex I) to the Chief of the Regional Surveys Division for evaluation and reference.
CSTs must select sufficient recovered points for GPS observation that are:
- well-distributed over the entire project area, otherwise additional control points must be established and referred to the old coordinate system;
- not disturbed (disturbed control points must not be used);
- intact but not meeting GNSS survey requirements must be observed by establishing a baseline between two nearest PRS92 control points and taking a side shot;
- supplemented with corner monuments of titled parcels when project controls/reference points are insufficient, with a verification survey to assess accuracy of the lot corners.
The Chief of the CST must submit the list of recovered points for GPS observation to the Chief of the Regional Surveys Division for approval.

GPS survey rules and field reports

PRS92 coordinates of selected recovered reference monuments must be derived through GNSS survey or conventional techniques.
GNSS surveys must be undertaken by persons authorized under RA 8560, as amended by RA 9200, known as the “Geodetic Engineering Act.”
The survey must use either:
- GNSS technique: static or fast static techniques referenced to two (2) existing PRS92 control stations of at least third (3rd) order accuracy (1:20000), conducted consistent with Sections 51–59 of DAO 98-12 (Revised Manual of Land Surveying Regulations in the Philippines); or
- Conventional technique: theodolites with Electronic Distance Meter or Total Stations tied/referred to existing PRS92 control points, with procedures consistent with DAO 98-12.
After completing the field survey, CSTs must submit a report to the RTD for Lands through the Regional Surveys Division Chief, containing:
- status of all reference monuments with the corresponding project control scheme;
- monument recovery sheets in the Annex H format, including description, name and number, geographic coordinates, physical status, location, photograph, sketch, access, and other relevant information;
- a narrative report describing methodology, instruments used, obstruction diagram at the time of observation, and other relevant information.
The Chief of the Regional Surveys Division must evaluate and approve the control points and reference monuments used for determining transformation parameters.

Local transformation parameters and accuracy

Local transformation parameters are determined by the LMS concerned on a cadastral survey basis for each city or municipality.
Old PTM and PRS92 grid coordinates of recovered control points must be used to determine and assess accuracy of local transformation parameters.
A minimum of two check points must be set aside for accuracy testing and must not be used in deriving the transformation parameters.
Transformation parameter determination follows steps that include:
- encoding new grid coordinates of recovered points using a spreadsheet template;
- computing local transformation parameters using a four-parameters transformation procedure.
The four-parameter transformation preserves shape through rotation, scaling, and translation, and is defined as a linear conformal transformation with shift, using constants A, B, C_E, C_N and variables X, Y, E, N with the stated mathematical model:
- A·X + B·Y + C_E = E
- -B·X + A·Y + C_N = N
The four parameters A, B, C_E, and C_N are solved from the set of equations formed using the recovered control points, solved using the method of least squares.
Weights must be applied based on observation accuracy level:
- Reference Monuments = 4
- Project Control Points = 2
- Lot Corners = 0.5
Residual errors must be computed at each point as PRS92 GNSS Observed − PRS92 Adjusted Coordinate using V_E and V_N.
Standard deviation in position must be computed using the redundant equations value 2(n − 2).
Points with residual errors exceeding 1.0 m must not be used in deriving transformation parameters.
The transformation procedure must be iterated until no significant residual error remains and standard deviation is within allowable limits.
Transformation accuracy must be evaluated by NAMRIA, in collaboration with LMB, including:
- assessing distribution and number of control points using the submitted project control scheme;
- ground validation by transforming check points to PRS92 and validating through ground survey;
- verification of adjoining cadastral projects by transforming selected lots along common boundaries and validating a minimum of ten (10) transformed and undisturbed lot corners through ground survey for consistency between adjoining municipalities.

Parameter approval, derivation, and adoption

Derived transformation parameters computed from the procedure must be used to solve PRS92 coordinates of all other control points using the same mathematical model, with known parameters A, B, C_E, C_N.
The Regional Technical Director for Lands must recommend approval of derived parameters to the LMB and the following must be submitted for assessment:
- field survey reports, including the documents covered under Section 5.3.1;
- all computation files generated (soft and hardcopy) for determination of local transformation parameters;
- an approved scheme showing recovered and observed project controls/reference monuments used for deriving transformation parameters;
- raw data of GPS observation conducted.
NAMRIA and LMB must implement approval mechanisms using control or reference point database build-up or other acceptable measures/strategies.

Integration, database build-up, and updates

Transformed PRS92 coordinates of reference points, project controls, and individual lots/parcels must be used to produce a control map in PRS92.
Control and visualization must be performed by plotting results digitally using appropriate mapping software and CAD software.
For cadastral survey controls, control points must be transformed to PRS92 using derived parameters and then plotted in PRS92.
For parcellary surveys, tie point coordinates must be integrated into PRS92 using derived parameters, and corner points must be transformed using the lot data computation program.
Adjacent parcels must be plotted using PRS92 coordinates to produce a cadastral map in PRS92.
PRS92 cadastral maps must be compared with existing cadastral maps to verify transformation accuracy.
When transformed parcellary surveys with computed technical descriptions are inconsistent with declared technical descriptions, a report must be submitted to the Regional Surveys Division Chief for evaluation and rectification based on existing policies and guidelines.
The Regional Surveys Division Chief must evaluate and recommend for approval by the Regional Technical Director for Lands the transformation for quality control.
Database build-up must include loading and merging transformed project datasets, periodic backup, restoration as necessary, user account management, and database performance tuning.
The national and regional cadastral databases must be managed by LMB and LMS, respectively; LMS must provide periodic postings to LMB to update the national cadastral database.
NAMRIA, as central data repository agency, must be periodically provided a copy of the national cadastral database by LMB and must extend technical assistance in maintaining the cadastral database management system in LMB and LMS.
LMB/LMS must issue specific guidelines for cadastral database management consistent with the Manual’s procedures and standards.
New cadastral and isolated surveys conducted after transformation must already be PRS92-compliant; LMB must provide inspection, verification, and approval guidelines, and lot data computation and relevant records must be incorporated into the digital cadastral database.
Converted cadastral data already converted may be incorporated into the cadastral database subject to evaluation by the Regional Surveys Division Chief.

Metadata, access systems, outsourcing, and sanctions

NAMRIA must design and develop a Metadatabase System for cadastral survey data, install it in LMS regional offices, and conduct training for regional CSTs.
Metadata must provide the basis toward creation of a Cadastral Spatial Data Infrastructure (CSDA).
Copying and/or transfer of cadastral datasets generated under the Manual without proper authority must be dealt with under applicable laws, rules, and regulations, and must be meted with appropriate penalties.
Regional LMS offices may contract out or outsource data conversion and survey subject to existing rules and regulations, provided current LMS staff cannot accommodate the activity and cost does not exceed the prevailing unit cost.
LMB must inventory all cadastral data in its custody and transfer them into the respective LMS offices for conversion and transformation into PRS92, including records cited in Section 4.2 and data stored in other media such as microfilms and magnetic disks/tapes.
NAMRIA and LMB must continue to oversee and provide technical assistance to LMS for conversion and transformation into PRS92, including development of a graphics database to support determination and approval of local and national transformation parameters.
NAMRIA and LMB must create task groups, provide mobile resources, monitor implementation, and extend technical assistance to enhance attainment of the Manual’s objectives.
Any violation or non-compliance with the Manual must be meted with appropriate penalties subject to existing laws, rules, and regulations.

Supplementation, repeals, and effectivity

Supplementary and amendatory procedures must be issued jointly by the NAMRIA Administrator and the LMB Director.
All procedures inconsistent with the Manual must be repealed or modified accordingly.
Adoption and effectivity require immediate adoption, with the circular adopted on 04 Feb. 2010.