反射標與距離檢定對三維雷射掃瞄儀精度影響評估—以Mensi GS200為例

Abstract

三維雷射掃瞄儀是一種能快速獲取大量高精度三維點位座標的新型測量儀器，適用於規則的、規範的及標準化的目標，同時亦適用於不宜移動的、危險的、非接觸性的、不規則的及非線性的複雜目標實體或實景進行資料獲取、建模與立體貼圖。近年來由於其測距效能的增加與定位精度的提升，使可應用的領域增廣許多，不論是在古蹟維護、工程測量、變形監測以及建築規劃等作業，都可使用三維雷射掃瞄技術以達到更好的精度及效能。 在工程方面的應用上，不同測站點雲之間的疊合常利用反射標作為連結點，而反射標的定位能力將大大地影響疊合的成果。本研究分析重複觀測對反射標定位精度的影響，並模擬反射標在不同的掃瞄角度與遮蔽程度時，得到定位成果的精度。 本研究另一個重點在於探討掃瞄距離對三維雷射掃瞄儀定位精度的影響，利用建置一個中長距離的戶外檢定場，對三維雷射掃瞄儀進行檢定工作，分析不同的掃瞄距離下定位的精確度與精密度；最後並以七參數法來改正儀器本身的系統誤差，經實驗結果計算後能提升掃瞄精度。

3D Laser Scanner is a kind of newly invented measuring instrument which can immediately obtain vast of 3D coordinates with high accuracy. It is suitable for not only the regular and standardized objects but also for the immobile, dangerous, irregular, complex physical objects. With the increase of its efficiency of distance measuring and the improvement of the positioning accuracy, the fields for the scanner to apply have been broadened. Cases like the maintenance of cultural assets, engineer surveying, deformation monitoring and architecture planning can be accomplished with higher accuracy and better efficiency by the technology of 3D laser scanning. As to the application to engineering, the merger of point clouds from different stations often uses targets as linking points, and the positioning ability of the targets would greatly influence the results of merger. This research analyses the influences on target positioning accuracy caused by repeated observations and by targets with different scanning angles and different degree of shelter. The other focus of this research is the positioning accuracy of the 3D Laser Scanner influenced by the distance of scanning. This research calibrates the accuracy and the precision of positioning under different scanning distances by setting up an outdoor calibrate field. Finally, the research rectifies the systematic errors of the instrument itself by using 7-parameters transformation, and the scanning accuracy and precision can indeed both be increased after the rectification.