How to define the dimensions of a sculpture?

Moreover, we found that among Museums, no uniform method of determining the dimensions of a sculpture has been agreed upon.  Whereas "height" mostly can be easily defined, "width" and "depth" measurements of an irregularly shaped object always depend on subjective choices. Our conclusion was that only objective geometrical models can accurately describe the proportions of such an art work. Therefore, we decided to make non-contact measurements of Rodin sculptures, that will allow for an exact morphological documentation of dimensions and surface structures. 

Some plaster versions (like the one in New York) are slightly smaller than others, for example, because they have been cast after an existing bronze cast. Foundry plasters that were duplicated by the foundry workers may be less detailed than corresponding studio or exhibition plasters. Some foundry plasters are worn off by casting processes or have been mollified by chemical agents used in moulding. Some plasters have even been cut apart for transport and were put together again. The bronzes also vary, because the foundries uses different methods (lost wax or sandcasting) and started from different plaster models. All these differences, that may help to answer questions about the real age and provenance of these copies, can only be determined by an exact comparison in three dimensions.

Over the last three years we have tested many different 3D-Scanners in museum situations. Currently we work, according to the task to be accomplished, with various kinds of equipment, which allow for a resolution of up to 12 lines per millimeter while capturing spatial co-ordinates. This way, the dimensions of a complex form can be determined very exactly. Moreover, not only Height, Length and Depth, but also all proportions and surface characteristics are recorded by this method.