The invention relates to the technical field of sewer defect detection, in particular to a sewer defect detection method based on YOLO11 and DDAA, and the method comprises the steps: obtaining marked sewer defects, measuring the length and width, calculating the area, setting three thresholds for comparison according to the area, dividing tiny, fine, medium and larger defect intervals, selecting tiny defect samples, extracting features by DDAA, evaluating the optimal
expansion rate, and determining each interval value. A matching table is generated,
training set defects are extracted and screened according to the table, types are manually marked, features are calculated to obtain a corresponding table, a crack ratio, a length-
width ratio and a threshold value in the table are stretched, rules are determined according to the same principle for other defects, and a morphological enhancement matching result is obtained. The method comprises the following steps: acquiring the length and width of a marked defect, calculating the area, setting a threshold value according to the area, dividing size intervals, selecting samples in each interval, extracting features, determining an
expansion rate, screening sample types according to the intervals, calculating morphological parameters, determining an enhancement rule according to the comparison of the parameters and the threshold value, estimating a potential defect area through
feature extraction, adjusting the
expansion rate, and
processing training data in combination with the rule. And
feature extraction is adaptive to defects of different sizes.