The Reverse Engineering of a Mature Product
The creation of a model of a mature product is relatively straight forward given access to accurate drawings. However, it should be recognised that many drawings and plans, which are freely available, are often representational and undated, even though they gave the appearance of accuracy.
Therefore, I suggest that most 'amateur' product modelling is really reverse engineering; and should be respected as such.
Unfortunately, this part of 'applied science' is not well developed. Very often the term, 'reverse engineering', is used to refer, superficially, to the recreation of drawings and shape, etc., with no regard to the engineering logic, 'behind them', such as: reasons for the choice of materials, tolerances etc.
In the case of a mature product, such as a cathedral, reverse engineering becomes the investigation of the (structural) design, which has evolved over time, such that the current, known, state can be achieved. Obviously, at this point, I am only considering the physical/ spatial aspects of the fabric. However, many other aspects, such as economics, plague and war etc., also had influence on the design decisions.
The (re)creation of the design information hierarchy is not simple; the generalised approach being that, in order for any 'parent' layer to be considered validated, it is necessary for the 'child' layers to be completed. The development of the latter serves to prove the 'parent' and provide an assurance that it is not likely to change.
With an existing product, like a catherdal, the exercise becomes that of recreating the information hierarchy through investigation, experiment, trial and error etc..
Thus, the reverse engineering process must develop from general to specific by a form of hypothesis based iteration. It is conceivable that the sequence could be almost complete on several occasions only to fail a test.
The reverse engineering process can only be considered complete when all tests have been satisfied. Further, this proving can involve a considerable amount of work in order to provide the necessary assurance.
In practice, digital reverse engineering is facilitated if attention is paid to a number of work aspects. These tend to be obvious and include: