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SURCON Technologist practice questions

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Question 1Surveying and Geoinformatics Practice

In a total station, which component is primarily responsible for measuring the horizontal and vertical angles electronically?

  1. The electronic distance measurement (EDM) unit
  2. The tribrach optical plummet
  3. The electronic theodolite encoder system Correct answer.
  4. The onboard data logger

Explanation

Angle measurement comes from the instrument's angular encoders, which read the rotation of the horizontal and vertical circles. The EDM unit handles distances, the optical plummet handles setup over the station mark, and the data logger stores observations.

Question 2Surveying and Geoinformatics Practice

A surveyor observes a slope distance of 150.000 m to a target, and the vertical angle from horizontal is 10 degrees. Taking cos(10 degrees) as 0.9848, what is the horizontal distance?

  1. 148.480 m
  2. 26.047 m
  3. 152.318 m
  4. 147.720 m Correct answer.

Explanation

Horizontal distance equals slope distance multiplied by the cosine of the vertical angle. Here 150.000 x 0.9848 gives 147.720 m. This reduction converts the measured slope distance onto the horizontal plane used for mapping.

Question 3Surveying and Geoinformatics Practice

In geodetic coordinate systems, what does the term 'geoid' describe?

  1. The reference ellipsoid fitted to the Earth's surface by least squares
  2. The plane tangent to the ellipsoid at a chosen origin point
  3. The equipotential surface of the Earth's gravity field approximating mean sea level Correct answer.
  4. The satellite orbit surface used for GNSS positioning

Explanation

The geoid is the equipotential surface of gravity that best approximates mean sea level, extended through the continents. Heights above it are orthometric heights, which is why geoid models are needed to convert GNSS ellipsoidal heights.

Question 4Surveying and Geoinformatics Practice

A closed traverse of four legs returns to its starting station. The sum of the measured interior angles is 359 degrees 58 minutes 40 seconds. What is the total angular misclosure?

  1. 40 seconds
  2. 2 minutes 40 seconds
  3. 20 seconds
  4. 1 minute 20 seconds Correct answer.

Explanation

For a closed polygon the theoretical angle sum is (n-2) x 180, which for four sides is 360 degrees. The difference between 360 degrees and 359 degrees 58 minutes 40 seconds is 1 minute 20 seconds.

Question 5Surveying and Geoinformatics Practice

Which statement correctly describes the purpose of a backsight in a differential leveling setup?

  1. It measures the horizontal distance between stations
  2. It checks the collimation error of the level
  3. It establishes the height of instrument from a point of known elevation Correct answer.
  4. It determines the elevation of the next turning point

Explanation

The backsight rod reading is added to the known elevation of the benchmark to compute the height of instrument. Foresights then determine elevations of forward points, and the arithmetic check verifies the level run.

Question 6Surveying and Geoinformatics Practice

In GNSS surveying, what is the primary role of a Continuously Operating Reference Station (CORS) network?

  1. Providing correction data and reference coordinates for real-time or post-processed positioning Correct answer.
  2. Measuring gravity anomalies for geoid refinement
  3. Serving as a physical monument for property boundaries
  4. Broadcasting satellite ephemeris updates directly to the constellation

Explanation

CORS networks stream observations and corrections from fixed, precisely known stations, enabling network RTK and post-processing. They improve accuracy and reduce the baseline length limitations of single-base RTK.

Question 7Surveying and Geoinformatics Practice

Which map projection preserves angular relationships at every point, making it suitable for navigation charts?

  1. Sinusoidal
  2. Albers equal-area conic
  3. Transverse Mercator with standard parallels
  4. Mercator Correct answer.

Explanation

A conformal projection preserves local angles and shape at the expense of area, and the Mercator is the classic conformal projection used for navigation. Equal-area projections such as Albers and Sinusoidal deliberately distort angles to preserve area.

Question 8Surveying and Geoinformatics Practice

A surveyor records a distance as 84.36 m on a plan drawn at a scale of 1:2500. What is the corresponding ground distance?

  1. 2.109 km Correct answer.
  2. 210.9 km
  3. 210.9 m
  4. 21.09 km

Explanation

At 1:2500, one unit on the plan represents 2500 units on the ground, so 84.36 m x 2500 = 210,900 m, which is 2.109 km. Checking the decimal place confirms the result.

Question 9Surveying and Geoinformatics Practice

In a traverse, which condition must be satisfied for a closed-loop traverse to be geometrically consistent?

  1. The sum of the interior angles must equal 180 degrees
  2. The sum of the departures and the sum of the latitudes must each equal zero Correct answer.
  3. The total distance must equal the closing line length
  4. The sum of the backsights must equal the sum of the foresights

Explanation

For a closed polygon traverse, the algebraic sums of latitudes (northings) and departures (eastings) must both be zero in the absence of error. Any residual is the linear misclosure, which is distributed by compass or transit rules.

Question 10Surveying and Geoinformatics Practice

A leveling run between two benchmarks 1.2 km apart yields a misclosure of 12 mm. Using the rule that allowable misclosure is 8 mm times the square root of the distance in kilometers, is the run acceptable?

  1. No, because the allowable misclosure is about 4.4 mm and 12 mm exceeds it
  2. No, because the allowable misclosure is about 8.8 mm and 12 mm exceeds it Correct answer.
  3. Yes, because the allowable misclosure is about 12.0 mm and 12 mm equals it
  4. Yes, because the allowable misclosure is about 8.8 mm and 12 mm exceeds it

Explanation

The square root of 1.2 is about 1.095, so the allowable misclosure is about 8.8 mm. The observed 12 mm exceeds this limit, so the run fails the check and should be repeated or investigated.

Question 11Surveying and Geoinformatics Practice

Which statement best explains why a projected coordinate system uses a false easting?

  1. To keep all easting coordinates positive within the zone Correct answer.
  2. To align the grid north with true north everywhere
  3. To correct for the curvature of the reference ellipsoid
  4. To convert orthometric heights to ellipsoidal heights

Explanation

A false easting is an arbitrary constant added to the central meridian coordinate so that eastings within the zone remain positive. It simplifies computation and avoids negative coordinates in field and mapping software.

Question 12Surveying and Geoinformatics Practice

A surveyor needs to establish control in a dense urban area where GNSS signals are frequently obstructed. Which approach is most appropriate?

  1. Use a single-base RTK setup with a 40 km baseline
  2. Establish a total station traverse tied to GNSS-derived control points outside the obstruction zone Correct answer.
  3. Abandon control and digitize positions from an aerial photograph
  4. Rely solely on autonomous GNSS positioning at each station

Explanation

When GNSS is unreliable, a total station traverse from accessible GNSS control preserves accuracy and provides redundancy. Long RTK baselines and autonomous positioning both degrade accuracy significantly in obstructed environments.

Question 13Surveying and Geoinformatics Practice

In a least-squares adjustment of a survey network, what does the standard error of unit weight indicate?

  1. The precision of the most precise observation only
  2. The number of redundant observations in the network
  3. The overall goodness of fit of the observations to the model Correct answer.
  4. The maximum residual among all observations

Explanation

The standard error of unit weight is derived from the sum of squared weighted residuals divided by the degrees of freedom. It reflects how well the observations fit the mathematical model and is used to scale the covariance matrix.

Question 14Surveying and Geoinformatics Practice

A surveyor measures the same distance six times: 120.02, 120.04, 120.01, 120.03, 120.02 and 120.06 m. What is the mean and what does the spread of the readings suggest?

  1. Mean 120.04 m, indicating a gross blunder
  2. Mean 120.03 m, indicating a constant scale error
  3. Mean 120.02 m, indicating a systematic error
  4. Mean 120.03 m, indicating small random scatter about the mean Correct answer.

Explanation

The sum is 720.18 m, so the mean is 120.03 m. The readings cluster tightly around this value with small variations, which is characteristic of random observational error rather than a blunder or systematic bias.

Question 15Surveying and Geoinformatics Practice

What is the fundamental difference between a geodetic survey and a plane survey?

  1. A geodetic survey accounts for the Earth's curvature while a plane survey assumes a flat surface Correct answer.
  2. A geodetic survey measures only horizontal angles while a plane survey measures only distances
  3. A geodetic survey is used only for property boundaries while a plane survey is used for mapping
  4. A geodetic survey uses only satellite methods while a plane survey uses only total stations

Explanation

Geodetic surveying models the Earth as an ellipsoid and includes curvature effects, which matter over large areas. Plane surveying treats the surface as flat, an approximation valid for limited extents.

Question 16Surveying and Geoinformatics Practice

In GNSS RTK surveying, what does the term 'ambiguity resolution' refer to?

  1. Determining the integer number of carrier cycles between satellite and receiver Correct answer.
  2. Correcting the ionospheric delay using a broadcast model
  3. Aligning the antenna height with the vertical axis
  4. Resolving conflicting coordinates between two reference stations

Explanation

RTK relies on carrier-phase observations, and the integer cycle ambiguity must be fixed to obtain centimeter accuracy. Once resolved, the phase observations behave like precise ranges.

Question 17Surveying and Geoinformatics Practice

A property boundary is described in a deed as running 'thence north 45 degrees east for 200.00 feet'. What does this description specify?

  1. An interior angle at the corner of the parcel
  2. A bearing measured from north toward east with a specified distance Correct answer.
  3. A deflection angle from the previous line
  4. An azimuth measured clockwise from south with a specified distance

Explanation

A bearing of N 45 degrees E is measured from the north meridian toward the east, and the deed also gives the distance. This is a standard bearing-and-distance boundary description.

Question 18Surveying and Geoinformatics Practice

When converting a magnetic bearing observed in the field to a true bearing, which quantity must be applied?

  1. The grid convergence of the projection
  2. The refraction correction for the line of sight
  3. The curvature correction for the Earth's radius
  4. The magnetic declination at the time and place of observation Correct answer.

Explanation

Magnetic declination is the angular difference between magnetic north and true north at a location and time. Applying it converts the observed magnetic bearing to a true bearing.

Question 19Surveying and Geoinformatics Practice

A total station is set up over a station and a backsight is taken, but the instrument is later disturbed. What is the most reliable way to detect the disturbance before continuing observations?

  1. Check the battery level and internal memory
  2. Re-level the instrument and assume the orientation is unchanged
  3. Recalculate the station coordinates from the previous setup
  4. Re-observe the backsight and compare the angle with the recorded value Correct answer.

Explanation

Re-observing the backsight verifies both the orientation and the setup geometry against the recorded reference. A discrepancy signals that the instrument moved and the setup must be repeated.

Question 20Surveying and Geoinformatics Practice

In a topographic survey, what is the purpose of interpolation between spot heights or contours?

  1. To correct for instrumental collimation error
  2. To estimate elevations at locations not directly observed Correct answer.
  3. To increase the number of field observations
  4. To convert grid coordinates to geographic coordinates

Explanation

Interpolation uses known elevations to estimate values at intermediate positions, allowing a continuous surface or contour lines to be drawn. It does not replace field observation but extends the information between measured points.

Question 21Surveying and Geoinformatics Practice

A surveyor measures a horizontal angle four times with a total station and obtains 89 degrees 59 minutes 40 seconds, 90 degrees 00 minutes 20 seconds, 90 degrees 00 minutes 00 seconds, and 89 degrees 59 minutes 50 seconds. What is the most probable value of the angle?

  1. 89 degrees 59 minutes 40 seconds
  2. 90 degrees 00 minutes 00 seconds
  3. 90 degrees 00 minutes 20 seconds
  4. 89 degrees 59 minutes 52.5 seconds Correct answer.

Explanation

The mean of the four readings is computed by summing the seconds: 40 + 20 + 0 + 50 equals 110 seconds, giving 27.5 seconds on average. The mean angle is therefore 89 degrees 59 minutes 52.5 seconds.

Question 22Surveying and Geoinformatics Practice

Which factor most directly determines the horizontal accuracy achievable with a total station EDM in reflectorless mode at long range?

  1. The signal return strength from the target surface and the beam divergence Correct answer.
  2. The number of stored points in the data logger
  3. The vertical angle reading resolution of the encoders
  4. The height of the instrument above the ground

Explanation

Reflectorless measurement depends on the amount of light returned from the surface and on how the beam spreads with distance. Weak returns and large beam footprints at long range degrade precision and accuracy.

Question 23Surveying and Geoinformatics Practice

A surveyor must transform coordinates from a local grid to a national grid. Two control points have known coordinates in both systems. Which transformation is minimally determined by these two points?

  1. A polynomial rubber-sheeting transformation of high order
  2. A seven-parameter Helmert transformation with three rotations
  3. An affine transformation with six independent parameters
  4. A four-parameter similarity transformation with scale, rotation and two translations Correct answer.

Explanation

Two common points provide four coordinate equations, which exactly determine the four parameters of a two-dimensional similarity transformation: scale, rotation and two translations. Higher-parameter models require additional control points.

Question 24Surveying and Geoinformatics Practice

In a least-squares adjustment, an observation is found to have a normalized residual of 4.2. How should this typically be interpreted?

  1. The observation is highly reliable and should be given extra weight
  2. The standard error of unit weight is too small
  3. The network has too many redundant observations
  4. The observation is a statistical outlier and should be investigated Correct answer.

Explanation

Normalized residuals are compared against a statistical threshold, commonly around three. A value of 4.2 exceeds that threshold, indicating the observation is inconsistent with the model and warrants checking or rejection.

Question 25Surveying and Geoinformatics Practice

A closed traverse has a linear misclosure of 0.045 m over a total traverse length of 900 m. What is the relative precision, and how is it normally expressed?

  1. 1:45, expressed as a ratio of misclosure to perimeter
  2. 1:20,000, expressed as a ratio of misclosure to perimeter Correct answer.
  3. 1:4,500, expressed as a ratio of misclosure to perimeter
  4. 1:900, expressed as a ratio of misclosure to perimeter

Explanation

Relative precision is the perimeter divided by the misclosure: 900 divided by 0.045 equals 20,000, so the ratio is 1:20,000. It is conventionally expressed this way to compare traverse quality across different lengths.

Question 26Surveying and Geoinformatics Practice

In a geodetic reference frame, what does the semi-major axis of the reference ellipsoid represent?

  1. The equatorial radius of the ellipsoid Correct answer.
  2. The geoid-ellipsoid separation at the origin
  3. The flattening ratio of the ellipsoid
  4. The polar radius of the ellipsoid

Explanation

The reference ellipsoid is defined by a semi-major axis a (equatorial radius) and a flattening f, from which the semi-minor axis b is derived. The semi-major axis is therefore the radius measured in the equatorial plane.

Question 27Surveying and Geoinformatics Practice

Which coordinate pair does a Universal Transverse Mercator (UTM) grid typically report for a point?

  1. Local bearing and distance from a zone origin
  2. Geocentric X, Y and Z in metres
  3. Easting and northing in metres within a specified zone Correct answer.
  4. Latitude and longitude in degrees

Explanation

UTM is a projected grid, so positions are expressed as metric easting and northing within a named zone, with a false easting applied to avoid negative values. Geographic latitude and longitude are the input, not the grid output.

Question 28Surveying and Geoinformatics Practice

A surveyor reads a staff at 1.245 m on a benchmark of known reduced level 52.310 m, then reads 2.870 m on a change point. What is the reduced level of the change point?

  1. 53.935 m
  2. 50.685 m Correct answer.
  3. 51.685 m
  4. 54.935 m

Explanation

The height of instrument is benchmark RL plus backsight: 52.310 + 1.245 = 53.555 m. Subtracting the foresight gives the change point RL: 53.555 - 2.870 = 50.685 m.

Question 29Surveying and Geoinformatics Practice

In a closed traverse, what does the angular misclosure represent?

  1. The difference between magnetic and true north at the first station
  2. The linear distance between the start and end stations after adjustment
  3. The difference between the measured sum of angles and the geometrically required sum Correct answer.
  4. The ratio of total traverse length to the perimeter of the figure

Explanation

For a closed polygon the interior angles must sum to (n-2)*180 degrees, or the exterior angles to (n+2)*180 degrees. The angular misclosure is the discrepancy between the observed sum and that theoretical value.

Question 30Surveying and Geoinformatics Practice

Which statement correctly describes a bearing of S 30 degrees E?

  1. Measured 30 degrees west of south, in the southwest quadrant
  2. Measured 30 degrees east of south, in the southeast quadrant Correct answer.
  3. Measured 30 degrees clockwise from the south line toward the west
  4. Measured 30 degrees east of north, in the northeast quadrant

Explanation

In quadrantal bearing notation the first letter gives the reference meridian and the second gives the direction of rotation. S 30 degrees E therefore starts at south and rotates 30 degrees toward east, placing the line in the southeast quadrant.

Question 31Surveying and Geoinformatics Practice

What is the primary purpose of a resection in a total station survey?

  1. To transfer a reduced level from a benchmark to a new point
  2. To set out a design point from known station coordinates
  3. To measure the height difference between two staff positions
  4. To determine the instrument station coordinates from observations to known points Correct answer.

Explanation

Resection observes known control points from an unknown instrument position and solves for that station's coordinates and orientation. It is the inverse of setting out, where the station is already known.

Question 32Surveying and Geoinformatics Practice

In GIS data management, what distinguishes a vector data model from a raster data model?

  1. Vector stores features as points, lines and polygons, while raster stores a grid of cells Correct answer.
  2. Vector requires a projected coordinate system, while raster requires geographic coordinates
  3. Vector records elevation only, while raster records only land cover classes
  4. Vector stores continuous surfaces only, while raster stores discrete features only

Explanation

The vector model represents discrete features geometrically as points, lines and polygons with attributes. The raster model partitions space into a regular grid of cells, each holding a value.

Question 33Surveying and Geoinformatics Practice

Which statement best describes the role of a datum transformation in surveying practice?

  1. It removes atmospheric error from GNSS pseudorange observations
  2. It adjusts the internal geometry of a traverse network
  3. It projects ellipsoidal heights onto a conformal map grid
  4. It converts coordinates between two geodetic reference frames using defined parameters Correct answer.

Explanation

A datum transformation relates coordinates expressed in one geodetic reference frame to another, using published parameters or a transformation model. Without it, coordinates from different datums cannot be combined meaningfully.

Question 34Surveying and Geoinformatics Practice

A plan is drawn at 1:500. A boundary line measures 63 mm on the plan. What is the corresponding ground distance?

  1. 31.50 m Correct answer.
  2. 0.315 m
  3. 3.15 m
  4. 315.0 m

Explanation

At a scale of 1:500 one unit on the plan represents 500 units on the ground. Multiplying 63 mm by 500 gives 31,500 mm, which equals 31.50 m.

Question 35Surveying and Geoinformatics Practice

A total station measures a slope distance of 250.000 m with a zenith angle of 85 degrees 00 minutes 00 seconds. What is the horizontal distance?

  1. 249.049 m Correct answer.
  2. 250.951 m
  3. 249.951 m
  4. 21.793 m

Explanation

Horizontal distance equals slope distance multiplied by the sine of the zenith angle. sin(85 degrees) = 0.996195, so 250.000 * 0.996195 = 249.049 m.

Question 36Surveying and Geoinformatics Practice

A surveyor must compute the area of an irregular parcel with many curved boundaries. Which approach is most appropriate?

  1. Use the planimeter reading from a sketch drawn freehand
  2. Apply the trapezoidal rule to two diagonal measurements only
  3. Multiply the longest chord by the longest perpendicular offset
  4. Use the coordinate method with points digitised along the curves at suitable intervals Correct answer.

Explanation

The coordinate (shoelace) method computes area from a closed set of boundary coordinates and handles curved edges when they are digitised at intervals fine enough to represent the curve. Accuracy improves as the interval along the curve shortens.

Question 37Surveying and Geoinformatics Practice

What is the effect of increasing the number of observations in a least-squares adjustment while keeping the geometry unchanged?

  1. The observation residuals become exactly zero
  2. The normal matrix becomes singular and the solution fails
  3. The standard error of unit weight must decrease to zero
  4. Redundancy increases and the estimated precision of parameters generally improves Correct answer.

Explanation

Additional independent observations increase redundancy, allowing better detection of errors and generally reducing the covariance of the adjusted parameters. Residuals do not vanish, because random error remains.

Question 38Surveying and Geoinformatics Practice

Which condition produces a systematic error in a levelling run?

  1. The observer reads the staff to the nearest millimetre each time
  2. The staff bubble is out of adjustment so the staff is held consistently off vertical Correct answer.
  3. The temperature varies slightly between morning and afternoon readings
  4. The instrument is set up at a different point for each leg

Explanation

A consistently out-of-adjustment staff bubble tilts the staff in the same direction on every sight, producing a cumulative bias rather than random scatter. Systematic errors do not average out with repetition.

Question 39Surveying and Geoinformatics Practice

In GNSS positioning, what does the PDOP value indicate?

  1. The total number of satellites tracked above the mask angle
  2. The signal-to-noise ratio of the strongest satellite
  3. The geometric dilution of precision based on satellite constellation geometry Correct answer.
  4. The time required to resolve carrier-phase ambiguities

Explanation

PDOP expresses how satellite geometry amplifies the theoretical ranging error into position error. A low PDOP indicates a favourable spread of satellites, while a high value indicates poor geometry.

Question 40Surveying and Geoinformatics Practice

A surveyor must set out a point 45.000 m from a station on a bearing of 120 degrees 00 minutes 00 seconds. Which procedure is correct?

  1. Orient the instrument to the backsight, turn the required angle, then measure the distance along that direction Correct answer.
  2. Stake the point by resection from three known control points
  3. Measure 45.000 m in any direction and then turn to the bearing
  4. Set the horizontal circle to zero at the required bearing and measure from the backsight direction

Explanation

Setting out requires the instrument to be oriented to a known reference direction, then the design angle turned and the design distance measured along the resulting line. This establishes the point relative to known control.

Question 41Surveying and Geoinformatics Practice

What is the fundamental difference between a geoid model and a reference ellipsoid?

  1. The geoid is defined only over oceans, while the ellipsoid applies only on land
  2. The geoid is a perfect sphere, while the ellipsoid is flattened at the poles
  3. The geoid is a projected grid, while the ellipsoid is a geographic coordinate system
  4. The geoid approximates mean sea level and is irregular, while the ellipsoid is a smooth mathematical surface Correct answer.

Explanation

The geoid is an equipotential surface of the Earth's gravity field that approximates mean sea level and has undulations. The reference ellipsoid is a smooth, mathematically defined surface used as a computational datum.

Question 42Surveying and Geoinformatics Practice

A surveyor observes a magnetic bearing of 47 degrees 30 minutes and the magnetic declination at the site is 4 degrees 15 minutes east. What is the true bearing?

  1. 51 degrees 45 minutes Correct answer.
  2. 43 degrees 15 minutes
  3. 47 degrees 30 minutes
  4. 52 degrees 45 minutes

Explanation

For an east declination, magnetic north lies east of true north, so the true bearing equals the magnetic bearing plus the declination. Adding 4 degrees 15 minutes to 47 degrees 30 minutes gives 51 degrees 45 minutes.

Question 43Surveying and Geoinformatics Practice

In a differential GNSS survey, what is the purpose of applying a baseline vector solution between a reference receiver and a rover?

  1. To cancel common-mode errors shared by the two receivers Correct answer.
  2. To estimate the ionospheric total electron content
  3. To transform the rover position into a local grid projection
  4. To convert ellipsoidal heights to orthometric heights

Explanation

Differencing observations between a reference and rover removes errors common to both, such as satellite clock and much of the atmospheric delay. The resulting baseline vector is then added to the known reference position.

Question 44Surveying and Geoinformatics Practice

A surveyor must establish horizontal control across a site where a single GNSS baseline exceeds the recommended length for reliable ambiguity resolution. Which strategy is most appropriate?

  1. Rely on broadcast ephemeris alone to shorten processing
  2. Reduce the observation session to a few minutes
  3. Break the network into shorter baselines tied to intermediate control points Correct answer.
  4. Increase the mask angle to exclude low satellites

Explanation

Long baselines degrade ambiguity resolution because ionospheric and tropospheric errors decorrelate between receivers. Establishing intermediate control and processing shorter baselines keeps the differencing assumptions valid.

Question 45Surveying and Geoinformatics Practice

In a level network, what does a loop closure test verify?

  1. That the sum of height differences around a closed circuit returns to the starting reduced level within tolerance Correct answer.
  2. That the staff graduations are correctly spaced
  3. That the instrument's line of sight is exactly horizontal over the whole run
  4. That the benchmark values are free of any error

Explanation

A loop closure compares the accumulated height difference around a circuit with zero, since the start and end point are the same. The residual misclosure is compared with an allowable tolerance to judge the run.

Question 46Surveying and Geoinformatics Practice

A total station measures a horizontal angle to a target with a stated standard deviation of 5 seconds of arc. If the distance to the target is 200 m, what is the approximate transverse positional uncertainty contributed by the angle?

  1. Approximately 50 mm
  2. Approximately 5 mm Correct answer.
  3. Approximately 500 mm
  4. Approximately 0.5 mm

Explanation

Transverse uncertainty equals distance multiplied by the angle in radians. Five seconds is about 2.42e-5 radians, and 200 m times that value gives about 0.0048 m, or roughly 5 mm.

Question 47Surveying and Geoinformatics Practice

A closed traverse of 5 sides has a measured interior angle sum of 540 degrees 00 minutes 40 seconds. What is the angular misclosure and the correction per angle?

  1. 40 seconds misclosure, 40 seconds subtracted from each angle
  2. 40 seconds misclosure, 8 seconds added to each angle
  3. 40 seconds misclosure, 8 seconds subtracted from each angle Correct answer.
  4. 20 seconds misclosure, 4 seconds added to each angle

Explanation

The required interior angle sum for a 5-sided polygon is (5-2)*180 = 540 degrees. The observed sum exceeds this by 40 seconds, so 8 seconds are subtracted from each of the five angles to distribute the correction.

Question 48Surveying and Geoinformatics Practice

A GNSS rover reports an ellipsoidal height of 102.450 m and the geoid undulation at that location is -28.310 m. What is the orthometric height?

  1. 74.140 m
  2. 28.310 m
  3. 102.450 m
  4. 130.760 m Correct answer.

Explanation

Orthometric height equals ellipsoidal height minus the geoid undulation: H = h - N. Subtracting a negative undulation gives 102.450 + 28.310 = 130.760 m.

Question 49Surveying and Geoinformatics Practice

In a least-squares adjustment, a computed residual is large but the observation's redundancy number is very small. How should this be interpreted?

  1. The observation is certainly a blunder and must be deleted
  2. The observation is poorly controlled by the network, so its residual is a weak indicator of error Correct answer.
  3. The observation weight must be increased to correct the residual
  4. The adjustment has failed and must be restarted

Explanation

Redundancy numbers indicate how much an observation is checked by the rest of the network. Low redundancy means the observation's error is largely absorbed into the solution, so its residual carries little diagnostic power.

Question 50Surveying and Geoinformatics Practice

A surveyor must convert a local grid coordinate set into a national grid where only two common control points exist. Which limitation applies to a four-parameter similarity transformation?

  1. It cannot model scale variation or rotation that differs across the area, and residuals cannot be assessed with only two points Correct answer.
  2. It requires at least ten common points to compute any parameters
  3. It cannot be applied to projected coordinates at all
  4. It automatically corrects for geoid undulation differences

Explanation

A four-parameter transformation assumes a single uniform scale and rotation, which may not hold over a larger area. With only two common points the transformation is exactly determined, leaving no redundancy to detect distortion.