(-215:Assertion failed) count >= 0 && (depth == CV_32F || depth == CV_32S) in function 'cv::arcLength'什么意思

This error message indicates that an assertion in the code has failed, and the count variable has a negative value. This could be caused by a bug in the code, such as an incorrect calculation, or an unexpected input value. To fix the issue, you should review the code and debug the problem to identify the root cause of the negative count value. Some common techniques for debugging include adding print statements to trace the flow of the program and using a debugger to step through the code.