Various improvements to inflatable membranes for use in three-dimensional imaging of interior spaces are disclosed. The threaded portion has a major diameter defined by a spiraling thread and a minor diameter. When a cache load is necessary, updated cache information is stored in the trace storage device. According to the invention, this is achieved without the use of complicated control circuitry. In contrast, each story of the earthquake-immune curtain wall system is structurally isolated from adjacent stories, which produces the beneficial effects of minimizing wall system damage and the attendant risks of falling debris during an earthquake.