Assertion failed getStructuringElement

A simple

cv::Mat element_cross=getStructuringElement(cv::MORPH_CROSS,cv::Size(3,3));

would give me a failed assertion

anchor.inside(Rect(0, 0, ksize.width, ksize.height))) in normalizeAnchor

I didn’t specify and anchor points, but it seem my anchor point isn’t in the rectangle.

the anchor should have been calculated automatically to be in the center… I can’t reproduce this.

check that you copied your code exactly. what else is going on in your code?

please prepare a minimal reproducible example.

Thanks for reply.
I managed to narrow it down to the usage of Boost. If I add Boost in CMakeLists, it will have the said issue above. My Boost version is 1.75.0. Hope you can reproduce it by this example:


cmake_minimum_required(VERSION 3.5)

project(cv_issue LANGUAGES CXX)


add_executable(cv_issue main.cpp)

find_package(OpenCV REQUIRED COMPONENTS core imgproc highgui)
target_include_directories(cv_issue PRIVATE ${OpenCV_INCLUDE_DIRS})
target_link_libraries(cv_issue ${OpenCV_LIBS})

#below lines are causing trouble
find_package(Boost REQUIRED)
target_include_directories(cv_issue PRIVATE ${Boost_INCLUDE_DIRS})


#include <iostream>
#include <opencv2/imgproc/imgproc.hpp>

using namespace std;

int main()
    cout << "Hello World!" << endl;
    cv::Mat element_cross = getStructuringElement(cv::MORPH_CROSS, cv::Size(3,3));
    cv::Mat element_rect = getStructuringElement(cv::MORPH_RECT, cv::Size(3,3));
    return 0;


Hello World!
OpenCV: terminate handler is called! The last OpenCV error is:
OpenCV(4.5.5) Error: Assertion failed (anchor.inside(Rect(0, 0, ksize.width, ksize.height))) in normalizeAnchor, file C:\For_CMake\source\opencv-4.5.5\modules\imgproc\src\filterengine.hpp, line 367
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Update: Maybe I included to much stuff from Boost, while all I need is Boost::property_tree. It’s a header-only library so I just did this so recklessly.

So instead, I changed CMakeList a little bit, which only includes header-onlys, and the issue is gone:

find_package(Boost REQUIRED)
#target_include_directories(meteoroid-thread PRIVATE ${Boost_INCLUDE_DIRS})
target_link_libraries(  cv_issue Boost::boost)

(source: stackoverflow)

But anyway there might be something behind this.

fascinating. boost is a beast. perhaps it’s worth filing an issue on boost and/or opencv and have the experts investigate further.