FREE. Our Face Mapping® analysis takes all the guesswork out of getting results. Not only will your Dermalogica Skin Therapist diagnose your skin’s concerns, she’ll prescribe a no-nonsense home care and treatment regimen to deliver your optimum skin health in your 14 unique zones. Using a sophisticated skin membrane sensor, the BT-analyze calculates the exact bio marker moisture content levels of the skin. Readings are accurate and helps determine the condition of your skin.