@Ashwin Pajanakr
I too have struggled getting OpenCV3 installed on my system. Fortunately, I found this youtube video to be extremely helpful.
https://www.youtube.com/watch?v=6j-Wy9j0TCs
I do not know for sure if it is specific to Python 3. But I do know that he was using python to test it out.
When you get to the point of compiling OpenCV from the source code, I would suggest using the cmake-gui
sudo apt-get install cmake-gui
The gui will allow you to see and enable/disable - graphically - all of the modules associated with OpenCV.
When configuring on the RPi, make sure you uncheck any references to cuda
. This is the only REQUIRED step for you to take to get the library compiled. But there are lots of other things you can add on.
NOTE: when you run make
It will take FOREVER on your PI. I would suggest running:
sudo make -j3
So that you run the compilation using 3 cores instead of 1. This will cut down the compilation from about 3-4 hours down to around 1-2.
I hope this helps...