Boundaries – Before you start

The following table represents the absolute and relative accuracy applicable to the scale at which the product was surveyed.

Original survey scale 99% confidence level 95% confidence level RMSE*
1:1250
Absolute Accuracy 0.9 m 0.8 m 0.5 m
Relative Accuracy +/- 1.1 m (up to 60 m) +/- 0.9 m (up to 60 m) +/- 0.5 m (up to 60 m)
1:2500
Absolute Accuracy 2.4 m 1.9 m 1.1 m
Relative Accuracy +/- 2.5 m (up to 100 m) +/- 1.9 m (up to 100 m) +/- 1.0 (up to 100 m)
1:10 000
Absolute Accuracy 8.8 m 7.1 m 4.1 m
Relative Accuracy +/- 10.1 m (up to 500 m) +/- 7.7 m (up to 500 m) +/- 4.0 m (up to 500 m)

*RMSE (root mean squared error) is the square root of the mean of the squares of the errors between the observations.

 

 

 

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25 Northwick Road
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WR3 7DS

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