economy of accuracy
surveys only ever undertaken for aspecific purpose and so should be as accurate they need to be , but not more accurate.in spite of modern equipment , automated systems , and statistical data processing the business of survey is still amanpower intensive one and needs to be kept to an economic minimum . once the requirement for asurvey or some setting out existing then part of the specification for the control survey may be derived and once this specification has been achieved , there is no requiement for further work.
whereas control involves workink from ,,the whole to the part ,, the specification for all survey products is achieved by working from ,, the part to the whole,, the specification for the control may be derived from estimation based upon experience using knwledge of survey methods to be applied , the instruments to be used and the capabilities of the personnel involved . such a specification defines the expected quality of the output by difining the quality of the work that goes into the survey .
alternatively astatistical analysis of the proposed control network may be used and this is the preferable approach in practice a good specification will involve acombination of both meyhods statistics tempered by experience . the accuracy of any survey work will never be better than the control upon which it is based . yuo cannot set out steel work to 5 mm if the control is only good to 2 cm .
whereas control involves workink from ,,the whole to the part ,, the specification for all survey products is achieved by working from ,, the part to the whole,, the specification for the control may be derived from estimation based upon experience using knwledge of survey methods to be applied , the instruments to be used and the capabilities of the personnel involved . such a specification defines the expected quality of the output by difining the quality of the work that goes into the survey .
alternatively astatistical analysis of the proposed control network may be used and this is the preferable approach in practice a good specification will involve acombination of both meyhods statistics tempered by experience . the accuracy of any survey work will never be better than the control upon which it is based . yuo cannot set out steel work to 5 mm if the control is only good to 2 cm .
