Created by: WenmuZhou

在这一行里，https://github.com/PaddlePaddle/PaddleOCR/blob/develop/tools/eval_utils/eval_det_iou.py#L140 使用的是shapely.geometry.Polygon包来计算两个框的iou，但是当gt和pred的框都多达数百之后，计算效率就会急剧下降，一张图片需要1s+，甚至更久，请问有什么好的解决办法吗？

对于倾斜矩形的计算，我写了下面的方法，速度会快很多，但是精度会不一致

def iou_rotate(box_a, box_b, method='union'):
    rect_a = cv2.minAreaRect(box_a)
    rect_b = cv2.minAreaRect(box_b)
    r1 = cv2.rotatedRectangleIntersection(rect_a, rect_b)
    if r1[0] == 0:
        return 0
    else:
        inter_area = cv2.contourArea(r1[1])
        area_a = cv2.contourArea(box_a)
        area_b = cv2.contourArea(box_b)
        union_area = area_a + area_b - inter_area
        if union_area == 0 or inter_area == 0:
            return 0
        if method == 'union':
            iou = inter_area / union_area
        elif method == 'intersection':
            iou = inter_area / min(area_a, area_b)
        else:
            raise NotImplementedError
        return iou