-228 opencv assertion_error ai_generated true

cv::error: (-228:Unknown error code 228) The homography mask has invalid size in function 'cv::findHomography'

ID: opencv/homography-mask-invalid-size

Also available as: JSON · Markdown · 中文

94%Fix Rate

87%Confidence

1Evidence

2024-03-12First Seen

Version Compatibility

Version	Status	Introduced	Deprecated	Notes
4.5.0	active	—	—	—
4.6.0	active	—	—	—
4.7.0	active	—	—	—
4.8.0	active	—	—	—
4.9.0	active	—	—	—
4.10.0	active	—	—	—

Root Cause

The output mask passed to findHomography has a size that does not match the number of input point pairs.

generic

中文

传递给findHomography的输出掩码尺寸与输入点对数量不匹配。

Official Documentation

https://docs.opencv.org/4.x/d9/d0c/group__calib3d.html#ga4abc2e5c3f5b8c9e8f6d7a5b6c0d1e2f

Workarounds

95% success Ensure the mask has the correct size: cv::Mat mask; cv::findHomography(srcPoints, dstPoints, cv::RANSAC, 3.0, mask); The mask is automatically resized by the function if passed as an output Mat. Do not pre-allocate it. Example: std::vector<cv::Point2f> src, dst; cv::Mat mask; cv::findHomography(src, dst, cv::RANSAC, 3.0, mask);
```
Ensure the mask has the correct size: cv::Mat mask; cv::findHomography(srcPoints, dstPoints, cv::RANSAC, 3.0, mask); The mask is automatically resized by the function if passed as an output Mat. Do not pre-allocate it. Example: std::vector<cv::Point2f> src, dst; cv::Mat mask; cv::findHomography(src, dst, cv::RANSAC, 3.0, mask);
```
90% success If using Python, simply call mask = None and let the function handle it: mask = cv.findHomography(src_pts, dst_pts, cv.RANSAC, 3.0, mask=None)[1].
```
If using Python, simply call mask = None and let the function handle it: mask = cv.findHomography(src_pts, dst_pts, cv.RANSAC, 3.0, mask=None)[1].
```

中文步骤

Ensure the mask has the correct size: cv::Mat mask; cv::findHomography(srcPoints, dstPoints, cv::RANSAC, 3.0, mask); The mask is automatically resized by the function if passed as an output Mat. Do not pre-allocate it. Example: std::vector<cv::Point2f> src, dst; cv::Mat mask; cv::findHomography(src, dst, cv::RANSAC, 3.0, mask);

If using Python, simply call mask = None and let the function handle it: mask = cv.findHomography(src_pts, dst_pts, cv.RANSAC, 3.0, mask=None)[1].

Dead Ends

Common approaches that don't work:

80% fail
The mask must have exactly as many rows as the number of point pairs; an arbitrary size causes an assertion failure.
65% fail
In certain overloads, omitting the mask is allowed, but if a mask is provided, it must be correctly sized; using an empty Mat can still trigger this error if the function expects a non-empty mask.