以光學框幅式影像解算水位面及水下物點三維坐標

Abstract

當攝影測量施作於多介質環境時，根據成像光線行經不同介質產生折射效應，於兩介質交界處發生路徑偏折，惟有正確地描述光線在不同介質中的幾何模式，才能獲致良好的物像對應關係。本研究旨在處理自空氣往水中拍攝的光學框幅式影像，透過光學成像幾何，在影像內外方位參數已知的條件下，進行水位面高度及水下物點坐標解算任務；並引入帶有約制條件的廣義最小二乘平差法，以妥善處理光學路徑中各隨機量以及考量讓物空間場景所提供的控制資訊能助益於整體求解成效。實驗內容包括(1).模擬資料建構場景資料，並利用平差模式，分析在各項參數變動下的參數解算品質，進而歸納出在雙像交會模式下，各項可能對於求解成果具有影響力之參數，其影響程度之多寡，歸結定性及定量分析。並進一步分析比較。(2).以實測場景驗證成果品質，展現本研究方法之可執行性及有效性。

To achieve correct photogrammetric measurement results in multi-media environments, where the camera and the object of interest are not as usual in the same optical media, the multi-media geometry has to be incorporated into geometric models. Therefore, the extension of standard photogrammetric imaging models by Snell’s Law for the handling of refraction effects is absolutely required. This study aims to determine the underwater object points and the water surface simultaneously through optical frame imagery in air-to-water photogrammetry with known orientation parameters. Besides, the generalized least-squares adjustment with constraint is drawn into the adjustment model not only to enable the uncertainties of orientation parameters, refractive index, and image point measurement to be individually or unitedly considered, but also to offer great flexibility in adopting prior information of parameters for analyzing the effectiveness of control information. The results from this study report both the qualitative discussions of solvability as well as the strategies solving for reducing high-conditioned geometry, and the quantitative analysis of the quality of determined underwater object points and the water surface. Apart from the analysis revealed from the simulation data, experimental tests in real scene are also conducted to show the feasibility and validity of the proposed methods.