As in a plane, translations and rotations are needed to do object or coordinate transformations. With pgSphere, it is done using Euler transformations (strans). On a sphere, there aren't real translations. All movements on a sphere are rotations around axes.

The general syntax for a transformation is always:

object operator euler

where operators are + for a usual transformation, - for an inverse transformation. You can transform any object having a pgSphere data type, except the data type sbox.

sql> SELECT set_sphere_output('DEG');
 set_sphere_output
-------------------
 SET DEG
(1 row)

sql> SELECT spoint '(30d,0d)' + strans '90d, 90d, 40.5d, XZX AS spoint';
   spoint
---------------
 (90d , 70.5d)
(1 row)
              

You can use the + and - operator as unary operators for transformations, too. +strans just returns the transformation itself, -strans returns the inverse transformation.

sql> SELECT set_sphere_output('DEG');
 set_sphere_output
-------------------
 SET DEG
(1 row)

sql> SELECT - strans '20d, 50d, 80d, XYZ' AS inverted;
      inverted
-----------------------
 280d, 310d, 340d, ZYX
(1 row)