NSPS CST Level II flashcards
NSPS CST Level II · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Traverse closure ratio
- Linear misclosure divided into total traverse length, expressed as 1:N. Computed as total length divided by the misclosure magnitude from summed latitudes and departures.
- Angular misclosure
- The difference between the measured sum of interior angles and (n−2)×180° for an n-sided closed traverse. It is distributed equally among angles when instrument quality is uniform.
- Compass rule
- A traverse adjustment that distributes misclosure proportionally to leg length. Each leg's latitude and departure corrections equal the total misclosure times that leg length over total length.
- Reciprocal vertical angles
- Vertical angles observed simultaneously in both directions between two points. Averaging them cancels curvature and refraction, so no separate correction is needed.
- Curvature and refraction correction
- For a single zenith angle, the combined correction is approximately 0.0206 times the square of the distance in thousands of feet, subtracted from the observed vertical angle.
- Horizontal curve tangent
- T equals R times the tangent of half the deflection angle. It locates the PC and PT from the PI station along the tangents.
- Middle ordinate
- M equals R times (1 divided by cosine of half the deflection angle, minus 1). It is the distance from the curve midpoint to the long chord.
- Vertical curve high point
- Located where the tangent slope is zero, at x equals negative g1 times L divided by (g2 minus g1), measured from the PVC.
- Combined scale factor
- Grid scale factor multiplied by elevation factor, where elevation factor approximates R divided by (R plus height). It converts ground distances to grid distances.
- Forced-centering error
- A centering offset of 1 mm at 100 m produces about 2 seconds of angular error. Centering precision matters more on short sights than long ones.
- Direct and reverse observations
- Observing each direction in both face-left and face-right positions. Averaging the two faces eliminates collimation error and reduces pointing error.
- PDOP threshold
- Position dilution of precision above 6 indicates degraded satellite geometry. Recording PDOP with each GNSS observation supports defensibility of the position.
- Balanced sight distances
- Keeping backsight and foresight lengths approximately equal in differential leveling. This cancels curvature, refraction, and residual collimation error.
- Field note correction practice
- Errors are struck through with a single line so the original entry stays legible. Erasures and overwrites are prohibited in defensible field records.
- Level loop tolerance
- A common third-order allowance is 0.05 times the square root of the loop length in miles, in feet. Second-order class I is about 0.035 times the square root.
- Monument evidence hierarchy
- Original monuments generally control over later distance measurements when the record is ambiguous. Written calls control when they are clear and the monument is uncertain.
- Coordinate inversion
- Bearing equals atan2 of delta easting over delta northing, normalized to 0 to 360 degrees. Distance equals the square root of the sum of squared deltas.
- Area by coordinates
- Twice the area equals the sum around the closed loop of Xi times Y(i+1) minus X(i+1) times Yi. The result is signed, so take the absolute value.
- A posteriori reference variance
- Computed as the weighted sum of squared residuals divided by (n minus u), where n is observations and u is unknowns. It indicates whether assumed weights were realistic.
- Error ellipse semi-axes
- Derived from eigenvalues of the 2x2 covariance submatrix for a point. The 95 percent ellipse scales the standard ellipse by 2.447 for two degrees of freedom.
- Residual blunder screen
- A least-squares residual exceeding roughly three times its standard deviation suggests a blunder rather than random error. Such observations are re-examined, not silently deleted.
- NAD27 to NAD83 shift
- The datum transformation shifts coordinates typically 10 to 100 meters across the conterminous United States. Mixing datums in one file without transformation records is a defect.
- Deliverable metadata lineage
- Must record datum, epoch, projection and zone, units, combined scale factor source, and adjustment run identifier. Without these the coordinates cannot be reproduced.
- Parcel closure check
- A metes-and-bounds description should close to its record area within the stated precision. A larger gap prompts review of calls, monuments, and transcription.
- Average end area volume
- Volume equals length times the average of the two end areas. It is suitable when cross sections change gradually between stations.
- Prismoidal volume formula
- Volume equals length divided by six, times the sum of both end areas plus four times the mid area. Preferred when areas change rapidly between sections.
- ALTA Table A items
- Optional survey requirements negotiated in writing between client and surveyor. The minimum standard requirements apply regardless of which optional items are selected.
- Map scale ratio
- A scale of 1 inch equals 100 feet is 1:1,200. At that scale, 0.03 inch on the map represents 3 feet on the ground.
- Contour interval rule
- The interval should not exceed one-tenth of the required vertical accuracy of the map. Index contours are labeled every fifth contour line.
- Legal description structure
- Begin at a corner of record, cite the monument, give calls in bearing and distance, and close back to the point of beginning with the area stated.
- Coordinate file QA
- Check for duplicate point numbers, mixed units, and mismatches between station-offset and coordinate values before releasing any file to a client or agency.
- Deliverable review checklist
- Confirm datum consistency, closure within tolerance, correct scale and legend, north arrow, and a complete signature and seal block before issuance.