calc_viewing_direction

% Viewing direction from P of perspective camera

 Usage:
   d = calc_viewing_direction(P)
  
   P - 4 x 3-projection matrix P = K*R*[I|-Z] 

   d - 3x1 vector viewing direction, not normalized

 Wolfgang Förstner 4/2013
 wfoerstn@uni-bonn.de 

 See also calc_P_from_KRZ, calc_KRZ_from_P, calc_Q_from_P

0001 %% Viewing direction from P of perspective camera
0002 %
0003 % Usage:
0004 %   d = calc_viewing_direction(P)
0005 %
0006 %   P - 4 x 3-projection matrix P = K*R*[I|-Z]
0007 %
0008 %   d - 3x1 vector viewing direction, not normalized
0009 %
0010 % Wolfgang Förstner 4/2013
0011 % wfoerstn@uni-bonn.de
0012 %
0013 % See also calc_P_from_KRZ, calc_KRZ_from_P, calc_Q_from_P
0014 
0015 function d = calc_viewing_direction(P)
0016 
0017 d = -P(3,1:3)'*det(P(:,1:3));