The surveying and mapping profession has a long tradition of determining and minimizing errors. This applies particularly to land surveying and photogrammetry, both of which tend to regard positional and height errors as undesirable. Cartographers also strive to reduce geometric and attribute errors in their products, and, in addition, define quality in specifically cartographic terms, for example quality of line work, layout, and clarity of text.
It must be stressed that all measurements made with surveying and photogrammetric instruments are subject to error. These include:
Human Errors in measurement (e.g. reading errors) generally referred to as gross errors or blunders. These are usually large errors resulting from carelessness, which could have been avoided through careful observation, although it is never absolutely certain that all blunders could have been avoided or eliminated.
Instrumental or Systematic Errors (e.g. due to maladjustment of instruments). This leads to errors that vary systematically in sign and/or magnitude, but can go undetected by repeating the measurement with the same instrument. Systematic errors are particularly dangerous because they tend to accumulate.
So–called Random Errors caused by natural variations in the quantity being measured. These are effectively the errors that remain after blunders and systematic errors have been removed. They are usually small, and dealt with in least–squares adjustment.
Measurement errors are generally described in terms of accuracy.
Student is abel to explain and apply quality assessment procedures (level 1, 2 and 3).