https://www.youtube.com/watch?v=ND2fa08vxkY
extrinsics
- where is the camera in the world?
 - 6 degrees of freedom
- (x,y,z) for location
 - and (a,b,c) for orientation localization estimates extrinsics
 
 - pinhole camera projection center defines camera system
 
intrinsics
- camera calibration & pose estimation
 - how to map a 3d world point onto a 2d image
 - described by 4-5 parameters
- C = camera constant, distance of image plane from camera center
 - m = scale difference in x-y
 - fx,fy = focal length
 - (x,y) principle point / optical center = pixel in the image through which the optical axis of the camera passes?
- describes where the point sits in the image