...
wget https://github.com/Itseez/opencv/archive/3.0.0.zip
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
OR:
git clone https://github.com/Itseez/opencv.git
git clone https://github.com/Itseez/opencv_contrib.git>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
unzip 3.0.0.zip
mkdir /sw/opencv/opencv-3.0.0/build
...