最小二乘CSG模型與影像最佳套合

半自動化模型式建物萃取法是目前航空攝影測量主要的研究方向，其中模型與影像的最佳套合演算法則是整個流程的關鍵。本文設計了兩種常見的房屋模型基本元件（primitive），依據建構實體幾何（Constructive Solid Geometry, CSG）的理論可將基本元件加以組合，以描述複雜的房屋模型。每個元件都具有一組形狀參數與姿態參數，藉由調整元件的模型參數可以改變元件的外觀、大小以及在物空間中的位置與姿態。本文所提出之最佳套合法是先將房屋元件依已知的內、外方位投影至航照像片，以消除模型邊線投影與房屋影像邊緣線像元之間的不符值為目標函式，採用最小二乘法逐步疊代求出最佳套合時的模型參數。為探討套合過程中各項因素對成果之影響，本文首先針對環域寬度、像片多寡及模型參數的收斂範團（pull-in-range）進行實驗分析。接著在航照像片上選取十棟成功大學校區周圍的各式建物，以人機互動方式逐一以矩形和屋脊形元件進行近似套合，再由電腦以最小二乘模型-影像套合法自動計算最佳套合時之模型參數，最後換算出屋頂角點之物空間座標與傳統航測立體製圖成果進行比較，以說明最小二乘CSG模型-影像最佳套合法之實驗精度及其可行性。

關鍵字

建物萃取；模型與影像套合；最小二乘；建構實體幾何；建物重建

並列摘要

Semi-automatic model-based building extraction is the major research topic of digital photogrammetry. The affectiveness of model-image fitting algorithm is the key of semi-automatic model-based building extraction. In this paper, a building is modeled by some combinative primitives, and model-image fitting is proceeded primitive by primitive. After fitting, complex buildings can be modeled by combining simple primitives defined by the theory of Constructive Solid Geomerty (CSG). A model primitive can be transformed into the object coordinate system to form its size and position with the shape and pose parameters. With the known photo exterior and interior orientation parameters, the primitive model and image features can be transformed into the photo coordinate system. The fitting is evaluated based on the correspondence between the projected model wire frame and the edge pixels. The least-squares fitting algorithm is applied to solve the optimal fitting and estimate the final model parameters. Ten houses composed of box and gable-roof primitives are tested for demonstration. The experimental results are compared with the data of manual measurements.

並列關鍵字

Building extraction ； Model-image fitting ； Least-squares fitting ； Constructive solid geometry ； Building reconstruction

國際替代計量

最小二乘CSG模型與影像最佳套合

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