IRR on Inspection and Approval of Surveys under PRS92

Legal basis and related issuances

Executive Order No. 192 (1987) is the basis for accelerating the implementation of land surveys through state policy.
Executive Order No. 45 (1993) adopts the Philippine Reference System of 1992 as the standard reference system for surveys in the Philippines.
Executive Order Nos. 280 and 321 amend EO No. 45.
DENR Administrative Order No. 2005-13 provides relevant revised guidelines for implementation of PRS92.
DENR Administrative Order No. 2007-29 provides the Revised Regulations on Land Surveys and supplies related procedures, forms, and referenced provisions.
Department Administrative Order No. 98-12 (Manual for Land Surveys) governs requirements on common points and related survey standards.
Republic Act No. 8560 (as amended by RA 9200) is used in the definition of a Geodetic Engineer (GE) and its professional credentialing system.
Sec. 73 to 80 of DAO 2007-29 are incorporated by reference for handling penalties arising from violations under this IRR.

Policy and objectives

The State policy is to accelerate land surveys in the entire country through effective and efficient adjudication and disposition of alienable and disposable lands of the public domain and other lands reserved or utilized by other government agencies (Sec. 1).
The Order aims to:
- prescribe rules that result in efficient processing of survey returns with non-compliant data submitted to DENR for verification and approval (Sec. 2(a));
- provide procedures to supplement existing IVAS methods in processing submitted survey returns (Sec. 2(b));
- provide procedures to review Global Positioning System (GPS) observations for lot surveys, including applicable transformation methods from local or arbitrary datum to PRS 92 datum (Sec. 2(c)).

Coverage and defined terms

The Order covers all survey returns of all isolated surveys pursuant to DAO No. 2007-29 (Sec. 3).
The covered classes of surveys include:
- Group Settlement/Townsite Subdivision Surveys (Sec. 3(a));
- Public Land Surveys (Sec. 3(b));
- Amendment Surveys (Sec. 3(c));
- Private Land Surveys (Sec. 3(d));
- Government Land Surveys including:
  - Friar Land Estate Surveys (Sec. 3(e)(i));
  - National Government Lands Surveys (Sec. 3(e)(ii));
  - Local Government Units (LGU) Lands Surveys (Sec. 3(e)(iii));
- Conversion Surveys (Sec. 3(f));
- Other Land Surveys intended for a specific purpose and not in the enumerated list (Sec. 3(g)).
Amendment Surveys are surveys covering untitled/undecreed properties by changing the number of lots therein without affecting the original technical descriptions of the boundary (Sec. 4(a)).
Common Points are points with known positions in both the local survey system and the PRS92 system (Sec. 4(b)).
Conversion Surveys transform/convert lots covered by approved graphical cadastral surveys, Cadm, and PCadm into numerical or regular cadastral lots with computation and plotting in the system of the cadastral project (Sec. 4(c)).
Geodetic Engineer (GE) refers to a natural person with professional expertise in surveying and mapping, issued a Certificate of Registration and Identification Card by PRC for the Board of Geodetic Engineering, pursuant to Republic Act 8560, as amended by RA 9200 (Sec. 4(e)).
Global Positioning System (GPS) is the satellite-based system of determining positions and elevations on Earth with WGS84 as datum (Sec. 4(f)).
Integration is transforming and consolidating land survey data sets into PRS92, including:
- inventory of survey data;
- physical recovery of location monuments or lot corners;
- observations of recovered monuments or corners; and
- generation of transformation parameters (Sec. 4(i)).
Isolated Surveys are all classes of surveys of isolated parcels of land used for agricultural, residential, commercial, resettlement, or other purposes covering areas not exceeding 1,500 hectares (Sec. 4(j)).
PRS92 is the modified Luzon datum used as reference system for all surveys in the Philippines pursuant to EO No. 45 (1993), as amended by EO No. 321 (2000) and EO No. 280 (2004) (Sec. 4(m)).
Survey Returns are the collective documents submitted by a Geodetic Engineer as a result of the survey and include primarily computations, reference data, maps, resulting plan, and supporting legal documents as necessary (Sec. 4(r)).
Verification is checking completeness of survey data and accuracy of results with respect to established standards such as errors of closure (linear, azimuth) and relative precision, in accordance with the Revised Manual for Land Surveys and related IRRs (Sec. 4(v)).
WGS-PRS92 Transformation Parameters consist of three (3) translations (shifts), three (3) rotations, and scale, specifically:
- Translation (shift): X = 127.62195 meters, Y = 67.24478 meters, Z = 47.04305 meters;
- Rotation: Rx = -3.06762a, Ry = -4.90291a, Rz = -1.57790a;
- Scale: 1.06002 (Sec. 4(u)).

IVAS workflow and supplementary procedures

The revised IVAS work flow must be followed and includes these sequential steps:
- submission of survey returns by licensed Geodetic Engineers or other government agencies for verification and approval (Sec. 5(a));
- preliminary examination to determine completeness and adherence to survey standards (Sec. 5(b));
- assessment of fees (verification, preparation and other fees), designation of kind of survey, assignment of survey number, and recording and indexing (Sec. 5(c));
- digital projection of submitted survey returns on the proposed Land Information Map (LIM) by the Projection Unit (Sec. 5(d));
- computation verification by the Computation Unit of boundary, reference, astronomical observations, traverse, recovered corners/common points, lot data, and lot corner settings (Sec. 5(e));
- verification by the Computation Unit of GPS-related observations including:
  - GPS receiver registration and calibration;
  - GPS data including raw GPS observations in appropriate format;
  - fully accomplished field sheets;
  - descriptions of all PRS92 control stations used; and
  - brand, model and serial number of GPS receivers and antennas (Sec. 5(f)(i)-(ii));
- verification of transformation accuracy including number, distribution, and accuracy of recovered common points and transformation technique adopted (Sec. 5(g));
- verification by the Cartography Unit of prescribed scale, centerline coordinates and plotting, adherence to cartography standards, completeness of features on plan, and completeness of notation and other survey details (Sec. 5(h));
- final examination by the Chief of Section (Aggregate Surveys or Original and Other Surveys) (Sec. 5(i));
- general review and recommendation by the Chief of the Survey Division (Sec. 5(j));
- approval by the Regional Technical Director (RTD) (Sec. 5(k)).
For non-compliant survey returns based on conventional survey equipment, supplementary IVAS procedures must be adopted:
- checking and evaluation of GPS survey returns in accordance with DAO 98-12, DAO 2005-13, and DAO 2007-29 (Sec. 6(a));
- verification of transformation accuracy including number, distribution, and accuracy of recovered common points and transformation technique adopted (Sec. 6(b));
- digital projection on the Land Information Map (LIM) (Sec. 6(c)).

Isolated survey submission and verification rules

Survey returns for isolated surveys must be submitted with the following documents accomplished in the LMB prescribed form under DAO 2007-29:
- a letter of transmittal enumerating the documents submitted, signed and sealed by the Geodetic Engineer (Sec. 7(a));
- an original drafting film plan, complete in details, indicated by appropriate conventional symbols and signed and sealed by the Geodetic Engineer (Sec. 7(b));
- a copy of the latest tax declaration when applicable (Sec. 7(c));
- original field notes and field notes cover, duly notarized (Sec. 7(d));
- GPS survey returns in digital format (Sec. 7(e));
- a PRS92 control map duly signed by the Chief of Party containing:
  - PRS92 control points used in the project;
  - tabulation of coordinates of control points;
  - map scale;
  - project boundary including locality;
  - adjoining lots with corresponding survey numbers;
  - prominent natural and man-made prominent features;
  - area;
  - project number; and
  - dates of survey and submission (Sec. 7(f)(i)-(ix));
- survey notification letter(s) (Sec. 7(g));
- lot data computations (Sec. 7(h));
- traverse computations (Sec. 7(i));
- astronomical observation computations (Sec. 7(j));
- GE Certificate, duly notarized (Sec. 7(k));
- Certificates of Instrument Registration (GPS/Total Station) (Sec. 7(l));
- a digital copy of all applicable survey returns (Sec. 7(m));
- Certificate of title duly certified by the Register of Deeds (ROD) concerned (Sec. 7(n)).
Verification of survey returns and related documents listed in Sec. 7 is performed by the supervising DENR Geodetic Engineer (Sec. 8).
The supervising DENR GE must stamp or write his/her name and affix his/her signature in all pages of the field notes, computation sheets, lot descriptions, and other related submitted documents during the verification process (Sec. 8).
After verification, if required documents are found in order, the Chief of Regional Surveys Division must sign the survey plan(s) and other necessary endorsement letters to the RTD for Lands for approval (Sec. 8).
If any document is incomplete and inaccurate, the RTD for Lands must immediately inform the GE who conducted the survey in writing (Sec. 8).

Transformation accuracy, control recovery, and coordinates

Transformation to PRS coordinates must be guided by these accuracy-determining factors:
- number of common points;
- distribution of common points around the project area;
- accuracy of positions of common points; and
- transformation technique adopted (Sec. 9(a)).
The provisions of DAO 98-12 on common points must be complied with, and the Order requires that higher accuracy generally requires more common points (Sec. 9(b)).
A single common point may determine the shift only in the unlikely scenario of a local survey network that is consistently and homogeneously accurate; otherwise, more common points must be used when the local survey network is irregular (Sec. 9(b)).
Redundant measurements must be used by recovering and observing more than the minimum number of common points to provide a clearer least-squares solution and consistency check (Sec. 9(c)).
A minimum of six (6) recovered control points per survey project is generally sufficient to generate transformation parameters when well distributed and homogeneously accurate (Sec. 9(c)).
Some recovered common points must serve as check points, and if residuals between actual and transformed positions are not acceptable, at least one of these courses of action must be taken:
- repeat deriving transformation parameters using a different set of common points;
- recover and observe more common points; or
- use a different transformation technique (Sec. 9(d)).
For locating positions of control points and lot corners:
- where recovered stations/corners are in open areas with line-of-sight to GPS satellites at least 150 above the horizon around the point, GPS receivers must be used to locate positions, and observations based on WGS84 must be converted to geodetic PRS92 coordinates using a 7-parameter transformation formula (Sec. 10(a));
- where a control point or lot corner is covered by vegetation or adjacent to structures/towers/fences higher than the tripod-mounted GPS receiver, the position must be located using an electronic total station by traverse from an existing control network or by a side-shot from the nearest GPS station established in an open area (Sec. 10(b)).

Transformation models and supplementary rules

Transformation to PRS coordinates must use the Helmertas four-parameter equation and Affine transformation (Sec. 11).
Under the Helmertas four-parameter equation, transformation must preserve shape via a linear conformal transformation with translation based on:
- A * X + B * Y + C_E = E and -B * X + A * Y + C_N = N (Sec. 11(a)),
- where A, B are scale and rotation constants, C_E, C_N are translation (shift) constants, and X, Y are PPCS-TM/Luzon 1911 coordinates while E, N are PPCS-TM/PRS92 coordinates (Sec. 11(a)).
The Helmertas model has four unknown parameters (A, B, C_E, and C_N) and requires two equations per control point; more than two points must be used for error adjustment through least squares (Sec. 11(a)).
Under Affine transformation, transformation must use six unknown parameters solved mathematically using three control points, and the Order requires more than three points for increased accuracy (Sec. 11(b)).
The affine model must follow:
- A * X + B * Y + C_E = E and -D * X + F * Y + C_N = N (Sec. 11(b)),
- where A, B, D, F are scale and rotation constants, C_E, C_N are translation (shift) constants, and X, Y are PPCS-TM/Luzon 1911 coordinates while E, N are PPCS-TM/PRS92 coordinates (Sec. 11(b)).
Additional or supplementary regulations must be issued when necessary by the Supervising Undersecretary, upon the recommendation of the Director of the Land Management Bureau (LMB) (Sec. 12).

Penalties, repealing, and operational consequences

Any violation of any provision of this IRR by a Geodetic Engineer or survey contractor constitutes sufficient ground for non-acceptance of the survey returns submitted for verification and/or approval (Sec. 13).
Violations must be dealt with in accordance with Section 73 to 80 of DAO 2007-29 (Sec. 13).
Inconsistent provisions from previous DENR orders, memorandum circulars, and other issuances are superseded, amended, or repealed (Sec. 14).