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a. Adjusted Coordinates – the resulting PRS92 coordinates after the application of the transformation parameters.
b. Analog data – traditional cadastral paper maps and records.
c. Cadastral data – records of cadastral and isolated surveys.
d. Cadastral database – a collection of logically related geo-referenced seamless digital vector data and raster data organized to facilitate data retrieval, exchange and integration, and a data model designed for all legal land objects managed by Land Management Bureau (LMB)/ Land Management Services (LMS) based on a survey of their boundaries. Such legal land objects are systematically identified by means of some separate designation and are defined by existing laws.
e. Cadastral map – a map made as a result of a Cadastral Survey, drawn to appropriate scale and showing all land parcels and important natural and man-made features within a municipality/project, for purposes of describing and recording ownership.
f. Cadastral survey projects – projects covering surveys of extensive areas covering an entire municipality or city consisting of several or many parcels of land undertaken for the purpose of title clearance and land registration.
g. Check points – control points used in assessing the accuracy of the transformation parameters derived.
h. Control Points – points whose coordinates are known, marked by a monument, and used as references for land surveys.
i. Conversion – the process of producing a digital version of an analog data.
j. Coordinate system – a fixed system of lines used to define the position of a point, line or plane.
k. Digital data – analog data recorded electronically that such storage and other operations can be made using computers.
l. Global Navigation Satellite System – a standard generic term for satellite navigation systems that provide autonomous geospatial positioning with global coverage.
m. Graphical Cadastre – a cadastral survey wherein the bearings and distances of the individual lots are determined using transit and stadia, scaling from photo maps, and other graphical methods.
n. Integration – the process of transforming and consolidating data, surveys and maps into PRS92.
o. Local transformation parameters – numerical constants used in the transformation of local or area-based coordinates into PRS92.
p. Metadata – a structured data which describes the characteristics of a feature.
q. Numerical Cadastre – a cadastral survey wherein the bearings and distances of the individual lots are determined from the computations based on the actual ground survey.
r. Philippine Reference System of 1992 (PRS92) – 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.
s. Residual – the difference between the observed and the computed coordinates based on the transformation parameters derived.
t. Source Map – the map outputs of a cadastral survey used in the conversion of existing cadastral data such as cadastral maps, and boundary index maps.
u. Transformation – the process of converting spatial datasets from one coordinate system to another.
v. WGS84 – an earth-centered, earth-fixed global reference frame for the Earth, currently the reference frame being used by the Satellite-based Positioning System (SPS), for use in geodesy and navigation.
a. lot data computation sheets4.1 Inventory of Records – A comprehensive physical inventory of cadastral records shall first be conducted by the regional land sector offices in order to assess the completeness and quality of the records and facilitate the integration of these datasets into PRS92. The results of the inventory shall be reported following the format shown in Annex B.1* to B.3*
b. lot description sheets
c. field notes
d. monument description books
e. monument recovery reports
f. municipal or boundary index maps
g. project control maps
h. traverse computation sheets
i. political boundary computation sheets
j. other relevant records
The conversion process shall be governed by the following order: (a) lot data computation sheets shall be the primary source of information for the cadastral lot data conversion, (b) in the absence of these, lot description sheets shall be used, (c) in the absence of the above, reconstruct the lot data computation and lot description sheets using the original field notes on file. (d) in case all of the above-mentioned sources of data are unavailable and after exerting all efforts thereon to retrieve from other sources, individual lots/parcels shall be resurveyed under the new reference system in accordance with the existing regulations thereof.
4.2.1 Project Controls and Reference Points – Using the keyboard, encode the PPCS-TM/Luzon 1911 or LPCS coordinates (Northings and Eastings) of project controls or reference points using the customized Geodetic Network Information System (GNIS) or other spreadsheet or database templates developed for the purpose (see Annex C* for the sample database template)4.3 Conversion of Bearings and Distances – In the absence of lot data computation sheets, lot description sheets containing the bearings and distances of all lines of boundary surveys and individual parcels shall be used as reference for the data conversion.
4.2.2 Individual Lots/Parcels – The Northings and Eastings coordinates in PPCS-TM/Luzon 1911 of lot corners including the corresponding tie point shall be encoded through keyboard entry using the customized Land Survey Data Management System (LSDMS) or other spreadsheet or database templates developed for the purpose (see Annexes D* and E* for the sample templates, respectively). The bearings and distances as computed from the encoded lot corner coordinates shall be checked with the technical descriptions indicated in the lot data computation sheets (LMB Form No. GSD-B-9A)
4.3.1 Project Controls and Reference Points – Encode the bearings and distances of the project controls or reference points using the customized GNIS or other spreadsheet or database templates developed for the purpose.4.4 Reconstruction of Lot Data Computation and Lot Description Sheets Using Original Field Notes On File - In the absence of lot data computation and lot description sheets, and in case the original field notes of the cadastral survey is still available on file, lot data computation and lot description sheets shall be reconstructed using the prescribed procedures and computations.
4.3.2 Individual Lots/Parcels – The bearings and distances of all lines in the lot, including the corresponding tie line, shall be encoded through keyboard entry using the customized LSDMS or other spreadsheet or database templates developed for the purpose. The coordinates of the individual lot corners shall be computed based on the technical descriptions of the lot (see Annex F* for the sample spreadsheet template.)
a. Recovered control points to be used in the determination of local transformation parameters shall be well-distributed over the whole project area. Otherwise, additional control points shall be established to satisfy this criterion. The newly established control points shall be referred to the old coordinate system.
b. Recovered control points that are disturbed shall not be used in the transformation. Control points that are found to be intact but do not satisfy the requirements for a GNSS survey shall be observed by establishing a baseline between two PRS92 control points nearest the recovered control point of interest, and taking a side shot on this point.
c. In case there is an insufficient number of existing project control and reference points recovered by the CSTs, the coordinates of corner monuments of titled parcels of lots shall be used in the determination of the transformation parameters. These lot corners must be stable and with minimum obstruction. The CSTs shall conduct a verification survey to access the accuracy of the lot corners.
The Chief of the CST shall submit the list of recovered points for GPS observation to the Chief of the Regional Surveys Division for approval.
5.3.1 Persons Authorized to Conduct the GNSS Surveys – the GNSS surveys shall be undertaken by persons authorized in accordance with RA 8560, as amended by RA 9200, otherwise known as “The Geodetic Engineering Act”, who are knowledgeable in GNSS surveys.5.4 Preparation and Submission of Field Survey Report – Upon completion of the field survey, the CST shall submit a report to the RTD for Lands through the Regional Surveys Division Chief. The report shall include the following:
5.3.2 Survey Methodology – The survey shall be undertaken using either of the techniques described below;a. GNSS Technique – The project controls and other reference points shall be surveyed using either static or fast static technique, referenced to two (2) existing PRS92 control stations of at least third (3rd) order accuracy (1:20000). The conduct of the survey shall be in accordance with Sections 51-59 of DAO 98-12 (Revised Manual of Land Surveying Regulations in the Philippines).
b. Conventional Technique – In case there are no available GNSS equipment, theodolites with Electronic Distance Meter or Total Stations may be used in determining the position of control point. The survey must be tied or referred to existing PRS92 control points. The procedures shall be consistent with the relevant provisions of DAO 98-12.
a. Status of all reference monuments with the corresponding project control scheme.5.5 Approval of the Selections of the Project Control Points for Transformation – The Chief of the Regional Surveys Division shall evaluate and approve the selection of control points and reference monuments to be used in the determination of transformation parameters.
b. Monument recovery sheets following the format shown in Annex H indicating the description, name and number, geographic coordinates physical status, location, photograph, sketch, access and other relevant information of the recovered monument.
c. Narrative report of the field survey conducted, including the methodology of observation, instruments used , obstruction diagram at the time of observation, and other relevant information.
6.1.1 Using a spreadsheet template, encode the new grid coordinates of the recovered points
6.1.2 Compute the local transformation parameters using the four-parameters transformation procedures. The transformation involves rotation, scaling and translation therefore preserving the shape of the feature being transformed.
The solution for the four-parameter transformation is a linear conformal transformation with shift. It is based on the mathematical model provided below:A * X + B * Y + CE = E
-B * X + A * Y + CN = Nwhere: A and B = scale and rotation constantsCE and CN = shift constants
X and Y = PPCS-TM/Luzon 1911 coordinates
E and N = PPCS-TM/PRS92 coordinates
Each of the recovered control points will have both old PTM and PRS92 grid coordinates. The parameters A, B, CE and CN are the solutions to the set of equations formed. The linear equations can be solved using the method of least squares (see Annexes K* and L* for the sample solution using spreadsheet and database templates, respectively).
Weights shall be applied in case the transformation points are a combination of reference monuments, project control points, and lot corners. The weights shall correspond to the level of accuracy by which these points were observed. Thus, the weights to be applied shall be as follows:Reference Monuments = 4
Project Control Points = 2
Lot Corners = 0.5
6.1.3 Analysis of Results – A comparison between the old PRS92 grid coordinates is made to assess the accuracy of the transformation. The steps are as follows:
6.2 Assessment of Transformation Accuracy – The accuracy of the transformation shall be evaluated by NAMRIA, in collaboration with LMB. The assessment procedure shall include, but not limited to, the following steps:6.1.3.1 Compute the residual error (VE , VN ) at each point:VE , VN = PRS92 GNSS Observed - PRS92 Adjusted Coordinate
6.1.3.2 Check if the PRS92 GNSS Observed coordinates are correctly measured by calculating the standard deviation in position, mp.
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where 2(n - 2) represents the number of redundant equations.
6.1.3.3 Analyze points with large residual errors. Points with residual errors exceeding 1.0 m should not be used in the derivation of the transformation parameters.
6.1.3.4 Solve for the new transformation parameters using the remaining control points. The remaining control points to be used in solving for the new transformation parameters must still satisfy the geometric conditions, i.e., the control points are well distributed over the project area.
6.1.3.5 Repeat the above steps until no significant residual error is computed and the standard deviation is within the allowable limit.
6.4.1 Preliminary Accuracy Checking – The distribution and number of control points used in the determination of transformation parameters shall be assessed using the project control scheme submitted.6.3 Derivation of PRS92 coordinates. – The transformation parameters computed from the preceding steps will be used to solve for the PRS92 coordinates of all other control points in the area. The same mathematical model in Section 7.1.2 shall be used to compute for the PRS92 coordinates:
6.4.2 Ground Validation of Transformation Parameters Using Check Points – Check points shall be transformed into PRS92 using the local transformation parameters derived. These check points shall be validated through a ground survey in order to assess the fit of the transformation parameters.
6.4.3 Verification of Adjoining Cadastral Projects – Selected lots located along the common boundary of adjoining municipalities/cadastral survey projects shall be transformed into PRS92 using the transformation parameters derived. A minimum of ten (10) transformed and undisturbed lot corners shall be validated through ground survey to check the consistency of the transformation between two adjoining municipalities.
In case of discrepancy, a review of the transformation procedure shall be conducted, from checking the accuracy of the original data, to the recovery and observation of reference monuments, and the determination of transformation parameters. Non-uniform/non-homogeneous residuals/distortions indicate possible erroneous cadastral survey. A resurvey of the whole cadastral survey project shall be conducted in case an erroneous survey has been verified.
6.4 Verification and Approval – The Regional Technical Director for Lands shall recomend approval of the derived parameters to the Land Management Bureau (LMB). The following shall be submitted for proper assessment:A * X + B * Y + CE = E
-B * X + A * Y + CN = N
In this case, the parameters A, B, CE , and CN are already known. X and Y are the PPCS-TM/Luzon 1911 grid coordinates. E and N are the PRS92 Easting and Northing, respectively (see Annexes L* and M* for the sample solution using spreadsheet and database templates, respectively).
a. Field Survey Reports, including the documents mentioned in Section 5.3.1The NAMRIA and LMB shall implement appropriate mechanisms for the approval of the parameters either through control or reference points database build-up or other acceptable measures or strategies.
b. All computation files generated, both in soft and hardcopy, in the determination of the local transformation parameters
c. Approved scheme showing the selected project controls and reference monuments recovered and observed for the derivation of transformation parameters.
d. Raw data of GPS observation conducted
7.1.1 Plot adjacent parcels using the PRS92 coordinates to produce a cadastral map in PRS92.7.2 Database Build-up – The cadastral database discussed herein refers only to the data/documents managed by LMB/LMS. For purposes of this Manual, however, it shall be limited to the data mentioned in Section 4, Paragraph 2.
7.1.2 Compare the PRS92 cadastral map with the existing cadastral maps to verify the accuracy of the transformation.
7.1.3 In cases where the transformed parcellary surveys with computed technical descriptions are not consistent with the declared technical descriptions, a report shall be submitted to the Regional Surveys Division Chief for proper evaluation and rectification based on existing policies and guidelines.
7.1.4 The Regional Surveys Division Chief shall evaluate and recommend for approval by the Regional Technical Director for Lands the transformation to ensure quality control.
a. Loading and merging of transformed project datasets to the cadastral database.The national and regional cadastral database shall be managed by LMB and LMS, respectively. LMS shall provide periodic postings to LMB in order to update the national cadastral database.
b. Periodic dataset and database back-up
c. Database and dataset restoration, as necessary
d. User account management.
e. Database performance tuning
8.1 Analog to digital conversion of bearings, distances, coordinates, and other technical descriptions of individual lots or parcels using spreadsheet and database;SECTION 9. Metadata and the Cadastral Spatial Data Infrastructure – NAMRIA shall design and develop a Metadatabase System for the cadastral survey data and shall be installed in the LMS regional offices. Training on the use and management of said system shall be conducted by NAMRIA for the regional CSTs.
8.2 Analog to digital conversion of all cadastral monument coordinates for each city or municipality using the four (4) local transformation parameters using spreadsheet and database; and
8.3 Derivation of four (4) local transformation parameters for each city or municipality using spreadsheet and database.