Error and Accuracy in Survey-Types of Errors Surveying
Error and accuracy in survey is one of the most important terms in surveying.Accuracy is the degree of perfection obtained.But precision is the degree of perfection used in the instruments.
Accuracy depends upon
1 Precise instruments
2 Precise methods
3 Good planning
Error and Accuracy in survey
Source of errors
Instrumental error
Error may arise due to faulty adjustment and imperfection of the instrument with which measurement is being taken.If the tape used in the operation is too long
Personal error
Error may arising due to the human.It is caused due to careless during taking observation
Natural error
Error may be arising due to the natural phenomenon such as temperature ,humidity ,gravity,wind,refraction and declination
Kinds of error
Mistakes
Mistakes are errors which arising from inattention,inexperience,carelessness and poor judgement or confusion in the mind of observer
Accidental errors
Accidental error are those which remain after mistakes and systematic errors have been eliminated and are caused by a combination of reasons beyond the ability of the observer to control.
Compensating error
This type of errors occures in both direction,that is both positive and negative.Therefore the resultant will be compensating.They are automatically cancelled.Some examples are
- Inaccurate bisection
- Inaccurate centering
- Careless in marking chain lengths
Systematic errors
A systematic error may always be same under same codition and it will have same size and sign.For example, in the case of a tape.If the tape of length x short is streched to N time then the total error in the tape will be N times x
The reason for the systematic error is
- Variation of temperature
- Variation of humidity
- Variation of pressure
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