Abstract: A method for the accurate measurement of the true dimensions and true geometric shape of an insulated, or otherwise wrapped tank, and for the subsequent calculation of the strapping table (strap chart) thereof, for any desired liquid height increment, without removing the wrapping (insulation), or draining and cleaning the tank on the inside. A number of points are identified and located on the tank shell, for which 3D coordinates measurement is desired. A target is used for each desired measurement point. The method uses a total station to determine the 3D coordinates of a minimum of 3 points on a reflective target. The target is attached to a bolt that can be threaded through the tank insulation until the end of the bolt makes snug contact with the tank shell.