approximately 20 to 30 feet smaller in diameter than the projection surface 170 those skilled in the art will appreciate that the audience platform 120 may have a shape other than circular one or more bridge structures 130 may penetrate the projection surface 170 to enable the audience to enter and exit the theater assembly 100 two bridge structures are shown in fig2 the bridge structure 130 is configured to prevent the audience from seeing any equipment mounted within the theater assembly 100 or any seams perforations or imperfections in the projection surface 170 this can be accomplished by enclosing the bridge structure or alternatively using frosted glass or similar wall structure to hide the equipment from the audience a light lock 210 may be located at the entry of each bridge structure 130 to prevent outside light from entering the theater assembly the light lock 210 generally consists of a series of curtains walls or panels that substantially blocks the direct line of sight into the bridge or the theater is blocked from outside the light lock 210 a railing 140 substantially surrounds the outer perimeter of the audience platform 120 to safely contain the audience the railing 140 may be constructed from a variety of known materials such as wooden or metal bars mesh or glass panels preferably the railings.