Question

i want to convert x,y,z coordinates to polar coordinates. I am getting (-) in y coordiantes. Can someone explain me why I am getting it. It would be great help.

I am reading these values (xyz , az_elev_r) from a software and can’t be changed.I am just not sure of the order of angles( az & elev). Using my code I get -y instead of y. It means there is 180 rotation.My code is:

xyz=[-0.564 3.689 -0.735;
      2.011 5.067 -1.031;
     -1.181 3.943 -1.825; % Reference values
    ];

%% az_elev_r–>xyz

 az_elev_r=[ 261.30 -11.24 3.80;
               291.65 -10.692 5.548;
               253.34 -23.897 4.50]; % Also Reference (degree)



az_elev_r(:,1:2)=deg2rad(az_elev_r(:,1:2));

r=az_elev_r(:,3);
az=az_elev_r(:,1);
elev=az_elev_r(:,2);


x=r.*cos(az).*cos(elev)
y=r.*sin(az).*cos(elev)
z=r.*sin(elev)

Answer 1

Your az_elev_r matrix is not consistent with your xyz reference.

>> [az, el, r] = cart2sph(xyz(:,1), xyz(:,2), xyz(:,3));
>> rad2deg(az)
ans =
          98.6924675475501
          68.3527736950233
          106.673911589314

Your answers are consistent with the values returned by the sph2cart function. (Example starts with your original input, before the dec2rad replacement.

>> [x, y, z] = sph2cart(deg2rad(az_elev_r(:,1)), deg2rad(az_elev_r(:,2)), az_elev_r(:,3))
x =
         -0.563766229670505
          2.01131973806906
         -1.17951822049783
y =
         -3.68422880893852
         -5.06709019311118
         -3.94153436658676
z =
         -0.740692730942158
         -1.02931719412937
         -1.82292172199717

Incidentally, you’re code will be more readable if you just use the sph2cart function, and work in radians, unless you are trying to understand the conversions for their own sake.