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General Terms
Measurement Error
The difference between the measured value and the true value, arising from various factors in the measurement process.
Measurement error is an unavoidable component of the measurement process. All measurements contain a certain error component, and the surveyor's task is to minimize and control these errors to ensure results meet requirements.
Types of errors:
- Systematic errors - constant or predictable deviations
- Random errors - unpredictable variations around the mean
- Gross errors - obviously incorrect measurements
Sources of systematic errors:
- Instrumental errors - uncalibrated instruments, wear
- Methodological errors - incorrect measurement method
- Environmental errors - temperature, atmospheric pressure effects
- Personal errors - operator's systematic deviations
Sources of random errors:
- Instrument setup imprecision
- Sighting imprecision
- Reading imprecision
- Atmospheric fluctuations
Error prevention and control:
- Calibration - regular instrument verification
- Proper methodology - selection of appropriate methods
- Repeated measurements - statistical analysis
- Check measurements - verification on known points
- Adjustment - error distribution
Error propagation:
In surveying, errors combine according to specific laws:
- Systematic errors add directly
- Random errors add quadratically (√(σ₁² + σ₂² + ...))
- More measurements mean smaller total random error
Allowable errors:
- Cadastral surveying - ±5 cm (urban), ±10 cm (rural)
- Topographic surveying - 0.4mm × M (scale)
- Class III leveling - ±10mm × √L(km)
- Construction stakeout - depends on structure
Understanding error sources and control methods is essential professional surveyor competence.