cv::moments does not handle the degenerated cases of a single point or aligned points

[lstahlman]

Mirrored from upstream: opencv#28222
Original author: @PierreChatelier · created 2025-12-18T07:41:27Z
Upstream labels: category: core, category: documentation
Selection: mirrored by mirror-issues.py

---

System Information

OpenCV 4.12.0
Windows 7
MSVC 2019+

Detailed description

std::vector<cv::Point> contour = {...};
cv::Moments m = cv::moments(contour);

as documented, cv:moments() can be used to determine the mass center of a set of points : $\bar{x}=\frac{m_{10}}{m_{00}}$, $\bar{y}=\frac{m_{01}}{m_{00}}$

However, it fails if :

• the contour is a single point
• the contour is a set of aligned points

in that case, m00 will be 0

I undersand that 2nd and 3rd order might be ill defined in that case, but my main use case if the mass center, and it's a pity to see it fail there.

Should it be fixed or only documented ?

Steps to reproduce

cv::vectorcv::Point p1 = {{1, 2}};
cv::vectorcv::Point ps = {{1, 2}, {2, 2}, {3, 2}};

cv::Moment m1 = cv::moments(p1); //m1.m00 is 0
cv::Moment ms = cv::moments(ps); //ms.m00 is 0

Issue submission checklist

• I report the issue, it's not a question
• I checked the problem with documentation, FAQ, open issues, forum.opencv.org, Stack Overflow, etc and have not found any solution
• I updated to the latest OpenCV version and the issue is still there
• There is reproducer code and related data files (videos, images, onnx, etc)