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Point or Co ordinate entry in AutoCAD

You may not know from your 2D studies but within AutoCAD there are four co ordinate systems:-

• Cartisian, the normal X,Y
• Polar, a distance at a bearing.
• Spherical, a distance from the centre to the surface of a ball at an angel in both the horizontal and vertical planes.
• Cylindrical,a distance from the centre to the surface of a tube at an angle in the horizontal plane and a height in the vertical plane.

Each of the systems may be absolute to the current UCS or relative to the last point and both absolute and relative states may relate to the world origin and plane or the current UCS.

This makes a total of 16 different methods to enter a single point !!

                         ABSOLUTE                    RELATIVE 


                  wrt UCS     wrt WORLD       wrt UCS       wrt WORLD   


   CARTESIAN      X , Y , Z   *X , Y , Z      @X , Y , Z    @*X , Y , Z 
              
   POLAR          D < A       *D < A          @D < A        @*D < A 
              
   CYLINDRICAL    D < A , H   *D < A , H      @D < A , H    @*D < A , H 
         
   SPHERICAL      D < A < Av  *D < A < Av     @D < A < Av   @*D < A < Av


            
           wrt UCS   = with respect to the current UCS.
              
           wrt WORLD = with respect to the world origin or plane.
               
           X,Y,Z  indicate the 3 cartesian axes. 


           D indicates a linear distance.


           H indicates a linear height above the UCS.


           A indicates an angular displacement in the UCS plane.


           Av indicates an angular displacement in the vertical plane.




         Eg  27<30<45   will define a point using spherical co ordinates


             27 mm from the UCS origin
             30 degrees from the X axis
             45 degrees from the UCS plane


         NB The first item is always a linear distance
            the trick is in the separator:-    ',' = cartesian


                                               '<' = angular