Obtain camera coords from 3 x 4 camera matrix

Hello forum, I am trying to find the coordinates of my Camera (X,Y,Z) using the technique shown [here](http://ksimek.github.io/2012/08/14/decompose/) However, I fond that because the points in my image does not have any height ie. Z = 0, the inverse of M becomes undefined. Would the camera coordinates I obtain be accurate if I define the all points in the world coordinate with a height of one ie. Z = 1 ? I would then just subtract the height of the camera by 1. The technique I am using to obtain the camera matrix is shown [here](https://www.youtube.com/watch?v=NWOL8yXL6xI&index=14&list=PLd3hlSJsX_Imk_BPmB_H3AQjFKZS9XgZm) at 42:45 I also set a44 = 1