Sri Lanka Licensed Surveyor Exam cheat sheet

A parcel is the closed area bounded by legally recognized lines; the deed area is evidence of quantity, not proof of boundary location.

Boundary evidence priority in cadastral reconstruction is original corner monuments and natural features, then original survey measurements, then later record measurements, then area.

Coordinate area: A = ½ |Σ(x_i y_{i+1} − x_{i+1} y_i)|, with the traverse closed and coordinates in one consistent grid.

Sri Lankan cadastral plans identify lot or parcel number, boundary marks, adjoining parcels, and state or private tenure; the plan and field notes form the survey record.

Corner mark types include concrete posts, iron pins, rock pegs, and natural features; the mark type and condition are recorded because they carry boundary weight.

When deed area conflicts with an identified original monument, the monument controls and the area is recomputed geometrically from the boundary.

Parcel identifiers must be unique within the land registry or cadastral coverage and stable across re-surveys; splitting a parcel creates new identifiers and retires the parent.

A cadastral survey closes on control of stated order; misclosure is checked against the applicable specification before coordinates are accepted.

Geodetic coordinates (φ, λ, h) refer to an ellipsoid; orthometric height H = h − N, where N is geoid separation.

The geoid is an equipotential surface approximating mean sea level; it is not an ellipsoid and varies with mass distribution.

Deflection of the vertical is the angle between the ellipsoid normal and the gravity vertical; it affects astronomical azimuth and zenith observations.

Slope distance S reduces to horizontal distance D = S cos θ for vertical angle θ; sea-level reduction applies D0 = D(R/(R+H)).

Geodetic azimuth differs from grid azimuth by convergence γ; grid azimuth = geodetic azimuth − γ for the usual convention.

A geocentric datum defines the ellipsoid position relative to Earth's centre; a local datum fixes it to a regional origin.

Sri Lanka's legacy Kandawala datum uses the Everest 1830 ellipsoid; modern GNSS work uses geocentric SLD99 or ITRF-compatible coordinates.

The combined curvature and refraction correction for a sight line is approximately 0.067 D², with D in kilometres and the result in metres.

UTM zone 44N covers 78°E–84°E, with central meridian 81°E, false easting 500,000 m, false northing 0, and scale factor 0.9996; Sri Lanka lies within it.

Transverse Mercator grid coordinates have a point scale factor that increases with distance from the central meridian; ground distances require the combined scale factor.

Combined scale factor = grid scale factor × elevation factor; grid distance = ground distance × combined scale factor.

Grid convergence γ ≈ Δλ sin φ; it rotates grid north relative to true north and is used in azimuth reductions.

A 7-parameter Helmert transformation uses three translations, three rotations, and a scale factor to convert between geocentric datums.

Kandawala coordinates must be transformed, not merely relabelled, before use with SLD99 or WGS84 coordinates.

Geoid models convert GNSS ellipsoidal heights to orthometric heights; using h as H without a geoid model causes metre-level errors.

Record the datum, projection, epoch, and coordinate order for every coordinate set; easting/northing order is not universal.

Latitude = D cos α and departure = D sin α for distance D and azimuth α measured from north.

Inverse: D = √(ΔE² + ΔN²); azimuth α = atan2(ΔE, ΔN), normalized to 0°–360°.

Traverse closure: Σ latitudes and Σ departures should be zero for a closed loop; residual components give linear misclosure.

Linear misclosure ratio = total misclosure / perimeter; it is expressed as 1:N and compared with the specification.

Area by coordinates uses the shoelace sum; a clockwise list gives negative signed area in the usual convention, so take absolute value.

Leveling rise or fall: rise = backsight − foresight; reduced level = previous RL + rise or − fall.

Coordinate transformation: [E;N] = [a −b; b a][x;y] + [tE;tN] for a 2D similarity with scale and rotation.

Rounding is applied only at final presentation; intermediate computations retain extra digits to avoid misclosure artifacts.

Bowditch (compass) rule distributes latitude and departure misclosure in proportion to leg length; transit rule distributes in proportion to absolute latitude or departure.

Angular misclosure = observed sum − theoretical sum; for an n-sided polygon the theoretical sum is (n−2)180°.

Least-squares observation model: L + V = AX; minimize VᵀPV, giving normal equations AᵀPA X = AᵀPL.

A posteriori variance factor σ̂² = VᵀPV / (n−u), with n observations and u unknown parameters; it tests adjustment consistency.

Redundancy number r = n − u; without redundancy, residuals cannot detect observational error.

Standardized residual = v_i / (σ_i √r_i); large values flag possible outliers or blunders.

Precision describes repeatability; accuracy describes closeness to truth; a precise traverse can still be systematically biased.

Constrained adjustment fixes known control; free adjustment estimates inner geometry; both report coordinate covariance.

Registration of Title Act No. 21 of 1998 makes the title register primary evidence; registration confers title subject to statutory exceptions and fraud provisions.

Deed registration records a transaction; title registration validates ownership and the parcel on the register.

Prescription Ordinance No. 22 of 1871 governs acquisitive prescription; the common statutory period for land is ten years, subject to legal conditions.

State Lands Ordinance No. 8 of 1947 and Land Development Ordinance No. 19 of 1935 govern state land disposal, permits, and reservations.

Partition Law No. 21 of 1977 governs partition actions and requires survey and valuation evidence for co-owned land.

Land Acquisition Act No. 9 of 1950 governs compulsory acquisition; survey plans identify the land to be acquired and affected interests.

Notaries attest deeds and certify identity and capacity; registration alone does not cure a defective instrument.

Bim Saviya implements systematic title registration; parcel maps and register records are linked by unique parcel identifiers.

Survey Act No. 17 of 2002 provides for the Surveyor General, licensed surveyors, survey standards, and the legal authority for cadastral surveys.

A licensed surveyor's plan is a legal document; false or misleading survey returns attract professional and statutory consequences.

Boundary marks are legal evidence; unauthorized removal or damage to survey marks is an offence under survey law.

Fixed boundaries are located by survey monuments and coordinates; general boundaries are indicated by physical features and are not fixed by measurement alone.

Original survey evidence prevails over later resurvey measurements when the later survey does not identify the original monument.

Where a boundary follows a water body, the legal water-boundary rule and the identified high-water mark or bank control the line.

A plan discrepancy is resolved by field evidence and the record hierarchy; changing a coordinate without a survey basis is not a boundary correction.

Easements and rights of way are interests that may appear on title but are not necessarily parcel boundary lines.

GNSS positioning uses pseudorange for code solutions and carrier phase for centimetre-level relative solutions.

Fixed integer ambiguities give the highest-accuracy RTK solution; float solutions are less precise and must be labelled.

PDOP measures satellite geometry quality; lower values indicate stronger geometry, while high PDOP increases position uncertainty.

Static relative positioning over longer sessions improves accuracy by averaging multipath and atmospheric error.

RTK or VRS corrections require a fixed reference network; the rover's link and coordinate datum must match the correction source.

GNSS gives ellipsoidal height; orthometric height requires a geoid model: H = h − N.

Multipath occurs when signals reflect from nearby surfaces; it is reduced by choke-ring antennas, good sky view, and appropriate observation times.

A GNSS-derived coordinate is not automatically on the national grid; transformation to SLD99 or Kandawala and projection to grid are separate steps.

Setting out transfers design coordinates to ground; the surveyor establishes control, computes setting-out data, and verifies as-built positions.

Grade = vertical rise / horizontal run; express as percentage or ratio and apply with the design alignment.

Cut or fill = design level − existing ground level; positive values indicate fill and negative values indicate cut under the usual convention.

Horizontal curve elements: tangent T = R tan(Δ/2), length L = RΔ with Δ in radians, and external E = R(sec(Δ/2) − 1).

Vertical curve K = L/A, where L is curve length and A is the algebraic grade change in percent; K gives the rate of grade change.

Deformation monitoring requires stable reference points outside the zone of movement and repeat observations with comparable precision.

Tunnel breakthrough accuracy depends on a common control network and regular transfer of azimuth and coordinates through the tunnel.

As-built surveys compare constructed works with design; deviations are reported in the project coordinate system and datum.

Contour interval is chosen from map scale, relief, and intended use; a smaller interval shows more detail but increases clutter and survey cost.

Contours never cross except at overhanging features; closed contours indicate hills or depressions, with hachures or labels distinguishing them.

A TIN represents terrain by irregular triangles; breaklines constrain triangle edges along ridges, channels, and embankments.

Spot heights and mass points supplement contours where relief is flat or features are critical.

Topographic feature codes provide consistent attribution; the same code should identify the same feature class across survey sheets.

DEM is a bare-earth elevation model; DSM includes vegetation and structures; DTM is often used for a terrain model with breaklines.

Positional accuracy is tested against higher-order control or checkpoints; contour accuracy is not identical to horizontal map accuracy.

Cross sections and profiles are derived from the same terrain model and must state datum, scale, and vertical exaggeration.

Map scale is the ratio of map distance to ground distance; a 1:10,000 map has 1 cm representing 100 m.

Generalization simplifies, displaces, merges, and exaggerates features to keep a map legible at scale; it changes geometric detail.

Grid north, true north, and magnetic north differ; magnetic declination changes with location and time and must be dated.

Map projection preserves chosen properties: conformality preserves angles, equivalence preserves area, equidistance preserves selected distances.

Cartographic symbolization uses colour, size, shape, and texture; classification breaks must be explicit in the legend.

Positional accuracy standards state the tested RMSE or confidence level; a map's scale alone does not guarantee its accuracy.

A map series requires consistent sheet lines, scale, datum, projection, and edge-matching across adjacent sheets.

Vector data stores features as points, lines, and polygons; raster data stores continuous values in a cell grid.

GSD = pixel size × flying height / focal length; it defines the ground footprint of one image pixel.

Photogrammetric overlap is typically about 60% forward and 20–30% sidelap; adequate overlap is required for stereo and matching.

Bundle adjustment jointly estimates camera poses, ground coordinates, and calibration using tie points and control.

An orthophoto is geometrically corrected for terrain and camera tilt; it is not a perspective photograph.

LiDAR measures range from pulse travel time; multiple returns can separate canopy, structures, and ground.

LiDAR point density is pulses or points per square metre; ground classification is required before a bare-earth DEM.

NDVI = (NIR − Red)/(NIR + Red); it indicates vegetation vigour and density from multispectral imagery.

Remote-sensing accuracy is reported with error matrices, overall accuracy, and kappa or class-specific measures.

A cadastre records parcels, boundaries, and rights for taxation and land management; a land registry records ownership and transactions.

A parcel identifier is the key linking cadastral map, register, and title; it must be unique and persistent.

Title registration records the state's guarantee of title; the register and cadastral parcel map must remain spatially consistent.

LADM (ISO 19152) is a land administration domain model covering parties, rights, responsibilities, restrictions, and spatial units.

Land tenure types include freehold, leasehold, permit, and license; each carries different transferability and security.

State land is managed under statutory reservation and disposal rules; alienation requires the legally prescribed process.

LIS data quality dimensions include completeness, positional accuracy, attribute accuracy, logical consistency, and temporal currency.

Land information access must balance transparency with personal data protection and statutory confidentiality.

A licensed surveyor must practise within competence and decline work where the required expertise or resources are absent.

Conflict of interest must be disclosed and managed; a surveyor should not certify work where a personal or financial interest affects judgment.

Professional negligence is a failure to exercise the standard of care of a reasonably competent surveyor, causing loss.

Survey records, field notes, and computations are professional evidence and should be retained under the applicable retention policy.

Quality control includes independent checks, calibration records, control verification, and documented review before plan issue.

A survey contract should define scope, datum, accuracy standard, deliverables, payment, and liability terms.

Confidential client and land data must be protected from unauthorized access, alteration, or disclosure.

Expert evidence must be independent, technically supported, and confined to the witness's expertise.

Chart datum is a low-water reference for charted depths; soundings are reduced to it so that most depths are positive.

Reduced depth = observed depth from transducer + transducer draft + tide height above chart datum, with sign conventions stated.

IHO S-44 defines hydrographic survey orders by intended use, depth, and required accuracy; order selection drives equipment and line spacing.

Multibeam echosounders produce swath bathymetry with beam angle and coverage; calibration and sound-velocity profiles are required.

Side-scan sonar images seabed texture and targets; it does not directly give accurate depth without ancillary data.

Tide observations and a local tide model are needed to reduce soundings; GNSS ellipsoidal heights require a separation model to chart datum.

Dredging volumes are computed between pre- and post-dredge surfaces in a common vertical datum.

Hydrographic positions require a horizontal datum and time-tagged positioning; latency between position and depth must be corrected.