- 期刊
以光學框幅式影像進行水位面及水下物點定位之定性分析
On Qualitative Analysis of Determining Water Surface and Underwater Object Point Using Optical Frame Imagery
摘要
水下空間資訊測量方式多元，搭配不同的載台及相異的感測方式，各有其適用場域及測製標的。本研究探討利用光學影像成像幾何，以光線追蹤方式進行攝影測量水下物點三維定位分析。為簡化探究主題，本研究目前基於靜止之水位面以及單一水中介質之假設，採用可掌握的物理及光學現象，在內外方位參數已知的條件下，依共線特性及折射效應建立自空氣至水中光線路徑，據以進行物像對應，解析影像中可視水下物點三維坐標；考量實務需求及作業條件，在物像對應模式中，水面位置可為未知參數或觀測量，在幾何條件俱足下，能與水下物點坐標一同解算；在物像對應模式上，本研究現階段主要探討對象為框幅式影像，並依前述條件建構帶有約制的廣義最小二乘法平差解算系統。為有效釐清同時解算水位面及水下物點課題重要幾何特性及定位品質，本工作現階段著重於設計模擬資料並以控制變因方式進行實驗及定性分析，成果包含幾何條件探討、參數可解性分析、影響因子及定位分量品質評估，並據以作為精進自空氣往水下進行水下場景三維定位任務之基石研究。
並列摘要
With the ever-changing photogrammetry technologies and different types of sensing instruments, a wide range of methods and alternatives can be applied for mapping underwater geospatial information. Among them, ray tracing of optical imagery is targeted to determine the underwater object points in this study. To simplify the task, it is assumed that all involved media are homogeneous and the water surface is still. Under the ideal physical and optical phenomenon with the known interior/exterior orientation parameters, the object-to-image correspondence of whole imaging paths of visible points can be retrieved by considering both collinearity condition and refraction effect. With that, the position of the water surface can be an observation or unknown parameter being solved together with underwater object points in accordance with practical requirements. Current study only considers imagery acquired by frame cameras and the generalized least-squares adjustment model with constraints is employed to carry out an effective parameter estimation. To characterize the core issues of this study and qualitatively verify the positioning quality varied with the influential factors, simulation data and experiments are well designed and conducted. The results of geometric conditions, solvability analysis of parameters and positioning quality tuned by influential factors are fully addressed and concluded, implementing a cornerstone for the air-to-water photogrammetric intersection solving for water surface and underwater object points.