QuestionsQuestions (GPPB Resolution No. 30-2013)
The State’s policy is to accelerate land surveys nationwide 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.
To (a) prescribe rules for efficient processing of survey returns with non-compliant data for verification and approval; (b) provide procedures that supplement existing IVAS methods; and (c) provide procedures for reviewing GPS observations for lot surveys, including applicable transformation methods to PRS92.
It covers all survey returns of isolated surveys for classes including: Group Settlement/Townsite Subdivision Surveys, Public Land Surveys, Amendment Surveys, Private Land Surveys, Government Land Surveys (including Friar Land Estate, National Government Lands, and LGU Lands), Conversion Surveys, and other land surveys intended for a specific purpose not included in the listed categories.
It refers to 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.
Transformation is the process of converting survey data from one coordinate system to another or from one datum to another—for example, converting local coordinates to the PRS92 Philippine Plane Coordinate System (PPCS) or converting GPS observations from WGS84 to PRS92 datum.
They are the parameters needed to transform GPS observations from WGS84 to PRS92 datum, consisting of three translations/shifts (X, Y, Z), three rotations (Rx, Ry, Rz), and a scale parameter.
The workflow includes: (a) submission by licensed Geodetic Engineers or agencies; (b) preliminary examination for completeness and standards compliance; (c) fee assessment, designation of survey kind/number, and recording/indexing; (d) digital projection on LIM; (e) computation verification of computations and recovered points; (f) GPS verification (receiver registration, calibration, raw observations, field sheets, control station descriptions, receiver/antenna details); (g) verification of transformation accuracy and recovered common points and technique; (h) cartography verification (scale, plotting, notation, completeness); (i) final examination by Chief of Section; (j) general review and recommendation by Chief of Survey Division; and (k) approval by RTD.
They include: (a) checking and evaluating GPS survey returns according to relevant DENR issuances; (b) verifying transformation accuracy (number/distribution/accuracy of common points and technique used); and (c) digital projection of submitted returns on LIM.
Returns must be submitted with multiple documents such as: letter of transmittal; original drafting film plan; latest tax declaration (when applicable); original field notes and notarized field notes cover; GPS survey returns in digital format; PRS92 control map signed by Chief of Party with specified control information; survey notification letters; lot data computations; traverse and astronomical computation; GE certificate (notarized); GPS/Total Station instrument registration certificates; digital copies of all applicable returns; and a certified copy of the title from the Register of Deeds.
Survey returns and related documents are verified by the supervising DENR Geodetic Engineer (GE), who must sign/stamp required documents. If required documents are in order, the Chief of Regional Surveys Division endorses for RTD approval. If incomplete and/or inaccurate, the conducting GE is immediately informed in writing by the RTD for Lands.
Transformation accuracy is determined by: (1) number of common points; (2) distribution of common points around the project area; (3) accuracy of positions of common points; and (4) transformation technique adopted.
Compliance with DENR DAO 98-12 is required. Generally, more irregular local networks require more common points. For least squares robustness and redundancy, it is best to recover more than the minimum; a minimum of six (6) recovered control/common points per survey project is generally sufficient if well distributed and homogeneously accurate.
They are common points reserved from initial transformation modeling and later used as independent checks by comparing actual positions to transformed positions. If residuals are unacceptable, actions include re-deriving parameters with different common points, recovering/observing more common points, or using a different transformation technique.
If in open areas with line-of-sight to GPS satellites at least 150 meters/above the horizon around the point, GPS receivers may be used (geocentric GPS observations converted to PRS92 via 7-parameter transformation). If covered by vegetation or adjacent to structures/towers/fences higher than the tripod GPS receiver, use an electronic total station via traverse from existing control or side-shot from the nearest GPS station in an open area.
It prescribes: (1) Helmert’s four-parameter equation (linear conformal transformation with 4 unknowns: scale/rotation and translations) mathematically solvable with two control points but usually requiring more points for least squares adjustment; and (2) affine transformation with six unknown parameters solvable mathematically with three control points but requiring more points for increased accuracy.
Violation is sufficient ground for non-acceptance of the survey returns for verification and/or approval, and it shall be dealt with according to Sections 73 to 80 of DAO No. 2007-29.
Fifteen (15) days after its publication in a newspaper of general circulation and upon acknowledgment of receipt of a copy by the Office of the National Administrative Register (ONAR).