For some shapes or objects, failing to plot the measurements

[sadaimudiNaadhar]

As you cans see in the below picture the contour plotting is not proper. So many missing curves.
Contours can be explained simply as a curve joining all the continuous points (along the boundary), having same color or intensity. This can be due to different intensity levels
More Info https://docs.opencv.org/3.3.1/d4/d73/tutorial_py_contours_begin.html