One of the most accurate ways, available to the Surveyor for determining the deformation of an open pit wall is by measuring distances using an Electronic Distance Measurement (EDM) instrument. This method, although quick and easy, is generally considered costly because it requires the placement of expensive glass prisms on the pit wall. The number of prism actually placed on a pit wall is kept
... [Show full abstract] to a minimum with the result that the full extent of the deformation may not be adequately defined. The acrylic reflector can provide an adequate and inexpensive alternative to the glass prism, thus allowing a more complete coverage of the pit wall at small cost.