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Python code to compute the intersection of two boundingboxes
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| def bb_intersection_over_union(boxA, boxB): | |
| # determine the (x, y)-coordinates of the intersection rectangle | |
| xA = max(boxA[0], boxB[0]) | |
| yA = max(boxA[1], boxB[1]) | |
| xB = min(boxA[2], boxB[2]) | |
| yB = min(boxA[3], boxB[3]) | |
| # compute the area of intersection rectangle | |
| interArea = abs(max((xB - xA, 0)) * max((yB - yA), 0)) | |
| if interArea == 0: | |
| return 0 | |
| # compute the area of both the prediction and ground-truth | |
| # rectangles | |
| boxAArea = abs((boxA[2] - boxA[0]) * (boxA[3] - boxA[1])) | |
| boxBArea = abs((boxB[2] - boxB[0]) * (boxB[3] - boxB[1])) | |
| # compute the intersection over union by taking the intersection | |
| # area and dividing it by the sum of prediction + ground-truth | |
| # areas - the interesection area | |
| iou = interArea / float(boxAArea + boxBArea - interArea) | |
| # return the intersection over union value | |
| return iou | |
| if __name__ == '__main__': | |
| # Pointing out a wrong IoU implementation in https://www.pyimagesearch.com/2016/11/07/intersection-over-union-iou-for-object-detection/ | |
| boxA = [0., 0., 10., 10.] | |
| boxB = [1., 1., 11., 11.] | |
| correct = bb_intersection_over_union(boxA, boxB) | |
| print('Correct solution - also analytical: {0}\n' | |
| 'Solution by published function: {1}\n' | |
| 'Solution by correction (ptyshevs): {2}'.format(correct, '0.704225352113', '0.680672268908')) | |
| print('Normalizing coordinates in a 100x100 coordinate system') | |
| boxA = [a / 100. for a in boxA] | |
| boxB = [b / 100. for b in boxB] | |
| correct = bb_intersection_over_union(boxA, boxB) | |
| print('Correct solution - also analytical: {0}\n' | |
| 'Solution by published function: {1}\n' | |
| 'Solution by correction: {2}'.format(correct, '0.964445166004', '0.680672268908')) | |
| print('Two boxes with no overlap') | |
| boxA = [0., 0., 10., 10.] | |
| boxB = [12., 12., 22., 22.] | |
| correct = bb_intersection_over_union(boxA, boxB) | |
| print('Correct solution - also analytical: {0}\n' | |
| 'Solution by published function: {1}\n' | |
| 'Solution by correction (ptyshevs): {2}'.format(correct, '0.0', '0.0204081632653')) | |
| print('Example in the comments from ptyshevs') | |
| boxA = [0., 0., 2., 2.] | |
| boxB = [1., 1., 3., 3.] | |
| correct = bb_intersection_over_union(boxA, boxB) | |
| print('Correct solution - also analytical: {0}\n' | |
| 'Solution by published function: {1}\n' | |
| 'Solution by correction (ptyshevs): {2}'.format(correct, '0.285714285714', '0.142857142857')) |
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