混凝土結構物受到物理或化學因素將會導致裂縫生成。本研究提出一套使用非接觸性量測方式來分析膨脹量與裂縫寬度間之關係，滿足對量測結果之一致性與重複性。使用非量測性相機近景攝影測量裂縫板塊，續以高解析度掃描器掃描成數值影像，以率定參數改正影像及二維投影轉換求得時間序列裂縫像空間影像及物空間關係。裂縫搜尋中為了提高其成果之可靠性因此採用半自動之方式，在裂縫分叉或端點之特徵輸入概略人工影像種子點。由於人工種子點並非準確落在特徵點，因此在種子點座落區域取目標視窗，使用基底函數轉換邊界偵測、區域增長消除雜訊區塊、裂縫區塊骨骼細化，接著尋找裂縫交叉點及端點，準確尋找出種子點應座落的位置，以此位置匹配後時期裂縫影像種子點，續以偵測前後時期裂縫邊界，利用局部套合求得高相對精度，求得裂縫成長的情況。 The elements of concrete structures suffering from chemical reactions tend to be an expansion phenomenon, which leads to cracks. Non-contact measurement is employed to analysis the relationship between concrete expansion and crack width. This paper deals with semi-automatic crack feature extraction from digital multi-temporal close-range images with non-metric camera and processes the image adjustment with lens distortion parameters. Furthermore, the relationship between image and object space is obtained by 2-D projective transformation to do tilt rectification. Only few roughly manual seed points are required on crotches of crack features. Then, the shape and position may be illustrated with automatic feature extraction in two-dimensional image space. Because manual seed points are not exactly located on the crack features, two methods are proposed to search the geometric crack features, such as crotches. Wavelet transformation, clumpping, thinning and crossing algorithm are processed sequentialy to reach the automatic feature extraciton purpose. Depending on these seed points, crack tracks and edges are determined by the method in this paper. Local image registration is utilized to raise relative accuracy and acquire the expansion of concrete cracks.
