OpenCV 的 RotatedRect 角度没有提供足够的信息 [英] OpenCV's RotatedRect angle does not provide enough information

问题描述

根据我的实验，RotatedRect 的角度变量返回的角度从 -90 到 0 度，这不足以确定对象是向左倾斜还是向右倾斜.

例如，如果角度是 -45 度，我们不能说是需要旋转 +45 度还是 -45 度来进行歪斜.

我正在使用的代码摘录:

RotatedRect rotate_rect = minAreaRect(contour);浮动 blob_angle_deg = 旋转矩形角；Mat mapMatrix = getRotationMatrix2D(center, blob_angle_deg, 1.0);

将物体向一个方向倾斜，我得到的角度从 0 到 -90 度，而将物体向另一个方向倾斜，我得到的角度从 -90 到 0 度.

我怎样才能找到我应该旋转我的图像以歪斜它的角度?

解决方案

借鉴Sebastian Schmitz和Michael Burdinov 回答我是这样解决的:

RotatedRect rotate_rect = minAreaRect(contour);浮动 blob_angle_deg = 旋转矩形角；如果 (rotated_rect.size.width <rotated_rect.size.height) {blob_angle_deg = 90 + blob_angle_deg;}Mat mapMatrix = getRotationMatrix2D(center, blob_angle_deg, 1.0);

所以，其实RotatedRect的角度并不能提供足够的信息来知道一个物体的角度，你还必须使用RotatedRect的size.width和size.height.p>

From my experiments, the angle returned by RotatedRect's angle variable goes from -90 to 0 degrees, which is not sufficient to determine if the object is leaned to the left or right.

For example, if the angle is -45 degrees, we cannot say if we need to rotate +45 or -45 degrees to deskew it.

An excerpt of the code I'm using:

RotatedRect rotated_rect = minAreaRect(contour);
float blob_angle_deg = rotated_rect.angle;
Mat mapMatrix = getRotationMatrix2D(center, blob_angle_deg, 1.0);

Leaning the object in one direction I get angles from 0 to -90 degrees, while leaning the object to the other direction I get angles from -90 to 0 degrees.

How can I find the angle by which I should rotate my image to deskew it?

解决方案

After learning from Sebastian Schmitz and Michael Burdinov answers this is how I solved it:

RotatedRect rotated_rect = minAreaRect(contour);
float blob_angle_deg = rotated_rect.angle;
if (rotated_rect.size.width < rotated_rect.size.height) {
  blob_angle_deg = 90 + blob_angle_deg;
}
Mat mapMatrix = getRotationMatrix2D(center, blob_angle_deg, 1.0);

So, in fact, RotatedRect's angle does not provide enough information for knowing an object's angle, you must also use RotatedRect's size.width and size.height.

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