Build and Install OpenCV-3 from source on Ubuntu 18.04

In this video, you will learn how to build Opencv-3 directly from source on Ubuntu 18.04

[N-eN]

Particularly:

 Instead of using wget with the cached link in the docs, so that we can get latest version. Also, opencv_contrib gives some additional functionalities not included in opencv

2.) cd opencv
git checkout 3.4.1
cd ..

cd opencv_contrib
git checkout 3.4.1
cd ..
 
Instead of 3.4.1 here, I entered 4.3.0 as that is the latest version

3.)cmake -D CMAKE_BUILD_TYPE=RELEASE \
-D \
-D INSTALL_C_EXAMPLES=ON \
-D INSTALL_PYTHON_EXAMPLES=ON \
-D \
-D \
-D BUILD_EXAMPLES=ON ..
 
I used this cmake command as the one given in the docs didn't work for me

4.) Finally, lines 87-94 in the link I have given. These lines rename the opencv file to 'cv2.so' so that opencv can be imported using the command 'import cv2' in python3

[tejasarlimatti]

Would be great if you'd pasted those commands in the description