摘要
隨著土木建築科技的突飛猛進與都會化的發展,人類的生活不再侷限於平地,傳統二維圖籍無法完整而具體地描述都市中林立的高樓大廈等空間資訊,唯有同時具備精確幾何關係與真實場景影像的三維像真建物模型(3D Photo-Realistic Building Model)才能鉅細靡遺地傳達三維空間資訊。現行三維建物模塑技術均需仰賴具有穩定內方位的專業相機拍攝影像,以人工處理相片的定位及方位求定,不僅需要購買昂貴攝影設備,而且費時、費工,無法大範圍進行模塑。近來智慧型行動電話(Smartphone)及平板電腦(Tablet PC)整合相機、GPS 及重力感測器於一身,可在拍照同時紀錄拍照當時的攝影方位及姿態,然其定位、定向精度尚未達到攝影測量要求。本研究擬採用浮測模型(Floating Model)法,將建物模型框架作為控制單元,提出一套最小二乘模型-影像套合法(Least-squares Model-image Fitting Algorithm, LSMIF)以疊代求解最佳之相片方位參數。並由攝影成像原理出發,推導原拍攝影像像元、物體表面點位、與最後材質像元之投影轉換關係,建立一套權衡規則使電腦可自動由多張拍攝影像中選取最適合的像元,以組成最後之材質影像。由於材質影像是逐像元組成,將可大幅提高呈像之正確率與真實性,使得三維像真建物模型的重建更真實、更精確、也更有效率。
關鍵詞:智慧型行動電話、平板電腦、像真模型、建物模塑、數位攝影測量
關鍵詞:智慧型行動電話、平板電腦、像真模型、建物模塑、數位攝影測量
Abstract
A semi-automated approach to modeling 3D photo-realistic buildings using a smartphone or a tablet PC is proposed in this research. The built-in GPS and G-sensor deliver the approximate 3D coordinates and pose parameters of the camera while taking pictures. However, they are not accurate enough for the further photogrammetric operations. The reconstruction of 3D realistic building models consists of three major issues: (1) modeling the object; (2) determining the image orientation; (3) creating the realistic texture image from photos. By introducing the “Floating Model” concept, the object modeling and image orientation problem can be solved efficiently through the semi-automatic model-image fitting procedures. Therefore, a friendly human-machine inter-acting interface program is necessary for operator to choose suitable model, and move, rotate, or resize the model so it can approximately fit to all of the images. Then, in our proposed approach, the Least-squares Model-image Fitting (LSMIF) is developed to solve the optimal fitting between projected model line segments and extracted edge pixels. Since the object model can be extracted and the photo orientation can be determined, the creation of realistic texture image, which is also called inverse mapping, can be automated by coordinate transforming and image resampling.
關鍵字
智慧型行動電話、平板電腦、像真模型、建物模塑、數位攝影測量
Smartphone, Tablet PC, Photo-realistic Model, Building Modeling, Digital Photogrammetry
Smartphone, Tablet PC, Photo-realistic Model, Building Modeling, Digital Photogrammetry