NSPS Certified Survey Technician Level I cheat sheet

Horizontal angles measured by a total station are typically recorded in degrees-minutes-seconds (DMS); 1 degree = 60 minutes = 3600 seconds.

Angular closure error for a closed traverse = (sum of measured interior angles) − (n − 2) × 180°, where n is the number of sides; a closed loop exterior-angle sum = (n + 2) × 180°.

Allowable angular misclosure is commonly set as c × √n, where n is the number of angles turned and c is the instrument's stated accuracy in seconds.

Zenith angle + vertical angle = 90°; slope distance SD relates to horizontal distance HD by HD = SD × sin(zenith) and to vertical difference VD by VD = SD × cos(zenith).

Differential leveling: elevation of a point = backsight reading added to the known elevation minus the foresight reading (HI = Elev + BS; Elev = HI − FS).

Level-loop misclosure is distributed in proportion to the number of setups or to the distance run, with the correction applied opposite in sign to the misclosure.

A prism constant (offset) error of K shifts every measured distance by K; an incorrect constant produces a constant distance bias that is not removed by averaging.

Instrument setup errors: an out-of-adjustment plate bubble causes a vertical-axis tilt error; a collimation error shows up as a horizontal-angle discrepancy between direct and reverse (plunged) readings.

For GPS/GNSS RTK work, horizontal precision is typically reported as a root-mean-square value; PDOP above about 6 indicates degraded satellite geometry and unreliable fixes.

Latitude of a course = distance × cos(bearing azimuth) and departure = distance × sin(bearing azimuth); a closed traverse must satisfy Σlatitude = 0 and Σdeparture = 0.

Linear misclosure = √((Σlatitude)² + (Σdeparture)²); relative precision = linear misclosure ÷ total traverse length, expressed as a ratio such as 1:10,000.

Compass (Bowditch) rule adjusts each latitude and departure in proportion to the course length divided by the total traverse length; the transit rule uses latitude/departure magnitudes instead.

Bearing is measured from north or south toward east or west (0°–90°); azimuth is measured clockwise from north (0°–360°); quadrant conversion depends on the sign pair of latitude and departure.

Area by coordinates (shoelace formula): 2A = Σ(Xᵢ × Yᵢ₊₁ − Xᵢ₊₁ × Yᵢ), with the last point wrapping to the first; take the absolute value and halve it.

Horizontal distance from coordinates: HD = √((ΔX)² + (ΔY)²); azimuth = atan2(ΔX, ΔY) normalized to 0°–360°.

Inverse between two points yields bearing, distance, and vertical difference from the coordinate pairs; verify units (feet vs. meters) before comparing to record data.

A plat or boundary description must close; the description's calls, area, and closure statement are checked against the computed deed closure before filing.

Metadata required with digital deliverables typically includes coordinate system/projection, datum and epoch, units, accuracy statement, and file format version.