電子測距儀稜鏡加常數率定

EDM Prism Additive Constant Calibration

使用電子測距儀配合稜鏡量測距離時，由於稜鏡之反射中心並非稜鏡整置時對點之中心，因而產生加常數。傳統的基礎測量課程中，常以量測一直線上三點間之三段距離，說明稜鏡進行加常數的率定。應用「標準基線」率定，亦是可行的方式。本文目的在討論這兩個方法的特性，以為教學討論之參考。稜鏡加常數確實為稜鏡構造之特性所引起，但是該常數的改正亦與電子測距儀本身相關。由於稜鏡設計的規格化，可由其產品規格獲得稜鏡加常數，本文針對實務測量建議應以產品規格為測量時設定之依據，如再以外業方式確認，則應是一個較穩當的作業方式。而若在以電子測距儀之加常數為率定主體時，「三段式」及其衍化型態應是較方便之作業方式。 When the Electronic Distance Meter (EDM) is utilized with a prism for measuring distance, there could be a non-zero additive constant between the measured value and the true distance. This may be caused by the fact that the optical center of the prism is not aligned with the physical center of the prism after the set-up. Frequently, the three distance set of collinear three point method is applied for calibrating this additive prism constant. But, the “standard baseline” scheme could be applied as well. This note explores the characteristics of these two calibration schemes. Prism constant is caused by the deviation of the above-mentioned two centers. But, the EDM unit also plays a role in this issue. As for a Standard Operation Procedurein surveying practice, it is recommended to use the prism constant obtained fromthe specification of the prismfor operation. If this could be verified with field calibration methods, the reliability would be even higher.The more information collected, the more reliable the calibration would be.And, while calibrating EDM constant, the “three segment method” and its other derived forms would be a recommended scheme.

When the Electronic Distance Meter (EDM) is utilized with a prism for measuring distance, there could be a non-zero additive constant between the measured value and the true distance. This may be caused by the fact that the optical center of the prism is not aligned with the physical center of the prism after the set-up. Frequently, the three distance set of collinear three point method is applied for calibrating this additive prism constant. But, the “standard baseline” scheme could be applied as well. This note explores the characteristics of these two calibration schemes. Prism constant is caused by the deviation of the above-mentioned two centers. But, the EDM unit also plays a role in this issue. As for a Standard Operation Procedurein surveying practice, it is recommended to use the prism constant obtained fromthe specification of the prismfor operation. If this could be verified with field calibration methods, the reliability would be even higher.The more information collected, the more reliable the calibration would be.And, while calibrating EDM constant, the “three segment method” and its other derived forms would be a recommended scheme.