CCL: geometric definition of major and minor groove

Dear users,
                 I want know the geometric definition (or algorithm) of the spaces filled by major and minor groove of  a DNA.  I know those base pairs by which major  and minor grooves are forming.  Using  this  little information, is it possible to solve my problem. If anybody aware about this problem, please let me know. It is very useful to me. I am waiting for your early reply.

Thanks in advance