在水準測量計算過程中，系統誤差改正是一項影響精度不可忽視的重要因子，換言之，測量成果中若存在系統誤差，將導致測量成果精度之降低。但是，各項系統誤差大小不同，影響程度各異，若各等級之水準測量，不管其精度要求如何，皆一體適用，全部加以改正，則將造成人力、物力與時間之浪費，有吹毛求疵之嫌。因此，如何在二三等水準測量中，適當的加入系統誤差改正，有效的提升測量成果之精度，又不致增加作業成本，為本研究之主要目的。
經理論分析與實際測試後發現二等水準測量須做視準軸誤差、折射誤差與正高改正（測區標高超過50 公尺以上），而三等水準測量，則須加入視準軸誤差，測區標高超過100 公尺以上，亦需加入正高改正。但是在視準軸誤差方面，不管是二等或是三等水準測量，若使用電子水準儀時，則因儀器已在內建之程式中自動加入改正，換句話說，根本不需另外再改正。因此，以後若電子水準儀完全取代光學水準儀，則此項系統誤差改正可取消。 When calculating the level measurement , the systematic error correction is an important factor which affects the accuracy of result and cannot be ignored . If the result involves the systematic error , it will be degraded . In other words , it must be corrected completely . However , different systematic error has different scale and the influence degree is different . If the level measurement of different order adopts same systematic error corrections , no matter how its precision is required , it will cause manpower , material resources waste and spend time and it will be suspected of nitpicking . Therefore , how to deal with the proper systematic error correction , to effectively improve the precision of the measurement , and unlikely to increase the project cost is the main purpose of this research .
As the result of theoretical analysis and practical test , the systematic error corrections of the second - order level measurement must include collimation error correction , refraction error correction and orthometric correction ( altitude over more than 50 m in the examining area ) . The collimation error correction and orthometric correction ( altitude over more than 100 m in the examining area ) must be involved in the systematic error corrections of third - order level calculation . It should be noted that if the optics spirit level is totally replaced by the electronic spirit level afterwards , the collimation error will be corrected automatically , since the electronic spirit level instrument has already built the formula of automatic correction . In other words , it does not nced to correct again at all .
