The principles of constructing a perspective were reversed in order to ascertain sizes and locations for the walls and doorways. The centre line of vision was assumed to be the centre of the photograph, and the eye level was assumed to be 1700mm. As the right hand and back walls as well as the ceiling are not in the photograph locations for these were also assumed.
Dimensions were taken from the plan and from the projections of the doorways back to the ground line.
The dimensions were used to construct a simple digital 3d model in VectorWorks, and a virtual camera set up (at the eye point) to generate a hidden-line perspective. This was then overlaid with the original photograph of the installation to check whether the dimensions taken from the reversed perspective were accurate. The perspective did align with the photograph, establishing the dimensions of the digital 3d model as being accurate for the production of a physical model.