Monday, 17 November 2014

Routine can kill passion (and mess up your data)

Documenting what you do, step by step, sounds easy. But it is not. Think, for example, of describing your morning routine. Would you be able to? And how accurately? Let’s give it a try: you wake up, get out of bed, prepare your coffee or tea... Wait. We forgot to say that you put your slippers on. Oh, and before that, that you probably turned off your alarm. You see? The things that we do automatically can be among the most complicated to document. So, when I started documenting my work, I realised how many small (and not so small) transformations and adjustments I apply to my data, without even thinking. Then I wondered if these actions should be documented as well.
The problem is, as always, where to draw a line and when “more information” becomes “too much information”. I have tried to keep the ontology slim, so that its complexity is not off putting for other researchers. However, the ontology is theoretically always open to further specification, that the user can decide to use or not. 
Just to give an example, I want to mention some of the operations that virtual archaeologists, in my experience, perform so often that they might go unnoticed. 

Elements of a series: isDerivedFrom
In the real world, of course, things are all unique. If measured, all the columns in the colonnade of the Iseum would have similar but different values. I have decided that the level of granularity of my representation doesn’t require that precision. Therefore, as in many other models of ancient buildings, all my columns have been artificially assumed to be identical (and perfectly aligned). Only one has been measured on site (the one that looked better preserved), and the others duplicated. To express this process, the subelement column that has been actually measured is documented as based on hard measurements (taken by me and available online at a certain url), while all the others are recorded as derived from other elements, i.e. derived from the value of the only measured one. 
My measurements of the ekklesiasterion of the Iseum.

Elements of a series: isConformedTo
Another possibility, is that a series of elements, such as the arches on the east wall of the ekklesiasterion, have actually been singularly measured but, for various reasons, it is not considered relevant to represent these differences visually in the model. In the case of the ekklesiasterion, my assumption is that the differences between the arches are mainly due to weathering and other accidents. And, although they were never perfectly identical in the past, my reckon is that they were meant to look so (a part from the central one which is wider), so I think it made sense to just model one arch and clone it four times. It is actually a more economical approach from a modelling point of view. 
How to represent this process in the documentation? In this case, all the arches had been measured, however they have been «conformed» (the word is a work in progress label. Any better ideas? «regularised»? «normalised»? ) to an average value. In the documentation, they have an attribute that has as value the range between the lowest and the highest values measured, and the percentage that this range is against the whole measured value. That sounds confusing… So, the four arches of the east wall of the ekklesiasterion (I have left out the wider central one) have a width between 159 and 164 cm. So, all the four of them have, as value of hasWidth an average 162 cm. However, the arches (transitions) also have two attributes which are “isConformedTo: average of four (159/164)”, and “hasVariation (again, the label is a work in progress): 3%”; i.e. the percentage of the variation against the whole average value: 5 cm on 162 cm.

If stating that the columns of a colonnade have not been singularly measured can sound unnecessary and pedantic (and, maybe, it actually is…), conforming the value of elements that had been measured might sound like a loss of information. However, in the documentation of the 3D element, there is always a link to the original measurements in case they are needed at a different stage of the research or by other scholars. 

No comments:

Post a Comment