1. Localization
   1. obtain localization
   2. compute path
      1. show directions to exhibits
      2. show directions to toilet
      3. show directions to exit
      4. show directions to shops
      5. show directions to restaurant
2. Purchase
   1. Buy
      1. Souvenirs
      2. Tickets
   2. Check availability
3. Information
   1. Display
      1. exhibition information
      2. exhibit information
4. Augmented reality
   1. Detect marker
   2. Display 3D model
   3. Transformation
      1. Rotatation
      2. Scaling