Laws + Regulations
20%of exam
RA 8560Land RegistrationPublic LandProfessional Seal
Mathematics
20%of exam
Least SquaresWeighted MeanTrigonometryEngineering Economics
Surveying Practice
20%of exam
Traverse ClosureLevelingSurvey ControlSpecial Surveys
Geodesy
20%of exam
Reference DatumGeoid + EllipsoidGNSSControl Networks
Cartography
20%of exam
Quick Facts
- Exam
- PRC GELE
- Subjects
- Five
- Subject weight
- 20% each
- TOS items
- 395 total
- Laws items
- 75
- Other subjects
- 80 each
- Pass
- 70% weighted average
- Subject floor
- 55%
Professional Law
- RA 8560
- Philippine Geodetic Engineering Act
- PRC
- Licensure-system administrator
- Board
- Geodetic-practice regulator
- Practice scope
- Surveying and mapping services
- Professional seal
- Authenticates responsible work
- Direct supervision
- Professional work accountability
- Ethics
- Competence, integrity, public welfare
Land Law
- Regalian Doctrine
- State owns default resources
- Public land
- Classify before disposition
- Torrens system
- Registered land-title system
- Cadastre
- Parcel boundary framework
- Metes and bounds
- Boundary course description
- Property survey
- Locates legal parcel limits
- Survey plan
- Graphical survey record
Accuracy vs Precision
Accuracy
- Near true value
- Bias-sensitive
Precision
- Repeatable observations
- Scatter-sensitive
Precision alone can be biased
Errors + Adjustment
- Residual
- Observed minus adjusted
- Correction
- Adjusted minus observed
- Weighted mean
- Σ(wx) ÷ Σw
- Least squares
- Minimize weighted residual squares
- Standard deviation
- Square root variance
- Relative precision
- Length ÷ closure error
- Distance formula
- √(ΔE² + ΔN²)
Surveying Math
- Azimuth
- Clockwise angle from north
- Bearing
- Quadrant direction angle
- Latitude
- North-south line component
- Departure
- East-west line component
- Law of sines
- Opposite sides and angles
- Law of cosines
- Included-angle triangle solution
- Present worth
- Future value discounted
Leveling Relation
HI equals known elevation plus BS.
HI height instrumentBS backsightFS subtracts
Survey Method Picker
- Need legal parcel limits→Cadastral survey(Corners and boundaries)
- Need terrain detail→Topographic survey(Relief and features)
- Need water depths→Hydrographic survey(Soundings)
- Need structure layout→Construction survey(Line and grade)
- Need network reference→Control survey(Accurate framework)
- Need traverse balance→Bowditch rule(Comparable observations)
- Need absolute position→GNSS(Satellite reference)
- Need relative elevations→Leveling(Height differences)
Field Surveying
- Traverse
- Connected measured courses
- Misclosure
- Unbalanced traverse vector
- Bowditch rule
- Length-proportional corrections
- Backsight
- Reading to known elevation
- Height of instrument
- Known elevation plus backsight
- Foresight
- Reading to target point
- Control survey
- Accurate reference framework
Bowditch Rule
Longer course carries larger correction.
Length proportionalTraverse correction
Survey Types
- Cadastral survey
- Parcel boundaries and corners
- Topographic survey
- Terrain and surface features
- Hydrographic survey
- Water depths and features
- Construction survey
- Layout and as-built checks
- Route survey
- Linear infrastructure alignment
- Mining survey
- Mineral-work location data
- Leveling
- Elevation difference measurement
Height Relation
H equals h minus N.
H orthometrich ellipsoidalN geoid undulation
Geoid vs Ellipsoid
Geoid
- Gravity-related surface
- Orthometric-height reference
Ellipsoid
- Mathematical reference surface
- GNSS-height reference
Use H = h − N
Geodetic Foundations
- Datum
- Coordinate reference framework
- Reference ellipsoid
- Mathematical Earth model
- Geoid
- Gravity-related height surface
- Ellipsoidal height
- Height above ellipsoid
- Orthometric height
- Height above geoid
- Geoid undulation
- Ellipsoid-to-geoid separation
- H = h − N
- Orthometric-height relation
Pseudorange vs Carrier
Pseudorange
- Code-based range
- Lower raw precision
Carrier phase
- Phase-based range
- Requires ambiguity resolution
Precision adds ambiguity challenge
GNSS + Control
- Pseudorange
- Code-based range measurement
- Carrier phase
- Precise phase measurement
- Integer ambiguity
- Unknown whole cycles
- Multipath
- Reflected-signal error
- Static GNSS
- Long simultaneous observations
- RTK
- Real-time differential positioning
- Grid convergence
- Grid-geodetic north difference
Grid vs Geodetic North
Grid north
- Projection-grid direction
- Map coordinate reference
Geodetic north
- Meridian-based direction
- Ellipsoid reference
Convergence relates directions
Projection Choice
Conformal angles; equal-area areas.
Shape priorityArea priority
Conformal vs Equal-area
Conformal
- Preserves local angles
- Distorts area
Equal-area
- Preserves relative area
- Distorts local angles
Choose the required property
Mapping + Adjustment Picker
- Need local-angle fidelity→Conformal projection(Shape priority)
- Need area comparison→Equal-area projection(Area priority)
- Need discrete features→Vector GIS(Points and lines)
- Need continuous surface→Raster GIS(Cell values)
- Need image accuracy→Ground control(Known coordinates)
- Need height conversion→H = h − N(Use geoid separation)
- Need best observations→Weighted mean(Weight precision)
- Need network adjustment→Least squares(Minimize residual squares)
Map Projections
- Map projection
- Earth-to-plane transformation
- Conformal
- Preserves local angles
- Equal-area
- Preserves relative area
- Scale factor
- Projection distance ratio
- Representative fraction
- Map-to-ground ratio
- Coordinate transformation
- Convert reference systems
- Grid north
- Projection-grid direction
GIS + Imagery
- Vector
- Points, lines, polygons
- Raster
- Grid-cell values
- Attribute
- Nonspatial feature data
- Orthophoto
- Geometrically corrected imagery
- Ground control
- Surveyed image reference
- Photo scale
- Focal length ÷ height
- Remote sensing
- Distance-based data capture
Common Traps
Title vs boundary
Title records rights ≠ Survey locates boundaries
Residual vs correction
Residual observed-adjusted ≠ Correction adjusted-observed
Geoid vs ellipsoid
Geoid gravity surface ≠ Ellipsoid mathematical surface
Grid vs geodetic
Grid uses projection ≠ Geodetic uses meridians
Conformal vs area
Conformal preserves angles ≠ Equal-area preserves area
RTK vs static
RTK real-time corrections ≠ Static longer observations
Last Minute
- 1.Five subjects; 20% each
- 2.395 TOS items total
- 3.Laws 75; others 80
- 4.Pass: 70%; no subject below 55%
- 5.Third failure: wait one year
- 6.Residual = observed minus adjusted
- 7.Bowditch distributes by course length
- 8.HI = elevation plus backsight
- 9.H = h minus N
- 10.Carrier phase needs ambiguities resolved
- 11.Conformal angles; equal-area areas
- 12.Use ground control for imagery
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