臺灣地區二、三等水準測量系統誤差改正之研究

Systematic Error Corrections of the 2(superscript nd) and 3(superscript rd) Order Leveling in Taiwan Area

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），而二等水準測量，則須加人視準軸誤差，測區標高超過100公尺以上，亦需加人正高改正。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 need to correct again at all.