Part 3 – Sources and Paradata

Before going into the bulk of how to model an archaeological site and why do it, I would like to spend a moment discussing the research that should be at the basis of the model itself. The fact that 3D Reconstruction is in its infancy brings many advantages and disadvantages to the table. On the one part, it is exciting to think there is so much we do not know as it means endless applications are there just waiting to be discovered. On the other hand however, there is a distinct lack of consistent methodology between projects and while some publication are clearly founded on extensive research (Dawson et al. 2011 amongst many others), others seem to be more loosely interpreted.

324t343t

Fig.1 – The first steps in modelling, based on a plan of the site to scale.

This is one of the reasons behind ‘paradata’, a term that has recently been applied to the field. To understand paradata we need to first discuss metadata. Especially in computer science, many authors have lamented the inability to replicate experiments involving code (Hafer and Kirkpatrick 2009; Boon 2009; Ducke 2012; Hayashi 2012). In the words of Marwick:

“This ability to reproduce the results of other researchers is a core tenet of scientific method, and when reproductions are successful, our field advances (Marwick 2016, pp.1).”

and

“A study is reproducible if there is a specific set of computational functions/analyses (usually specified in terms of code) that exactly reproduce all of the numbers and data visualizations in a published paper from raw data (Marwick 2016, pp.4).”

Essentially the debate is that publishing results is not enough, but that instead we should include additional information, such as settings used in a program or the raw code. This collection of information is referred to as ‘metadata’. Some authors on the other hand have taken it a step forward, arguing that we should include descriptions of the process, a discussion of the choices made and the probabilities (Denard 2009; Beacham 2011, D’Andrea and Fernie 2013). This ‘paradata’ is best described in the London Charter, which is the first attempt to creating a methodology in 3D Reconstruction:

“Documentation of the evaluative, analytical, deductive, interpretative and creative decisions made in the course of computer-based visualisation should be disseminated in such a way that the relationship between research sources, implicit knowledge, explicit reasoning, and visualisation-based outcomes can be understood (Denard 2009, pp.8-9).”

Given that a major critique in 3D Reconstruction is accuracy (Miller and Richards 1995; Richards 1998; Devlin et al. 2003; Johnson et al. 2009), paradata is our way to defend ourselves. While it is impossible to create the perfect model, by demonstrating the process behind the reconstruction allows a user to understand the interpretation given and draw their own conclusions.

Roman Villa 4

Fig.2 – A highly speculative Roman Villa. Without knowledge of the process it is impossible to know how accurate each element is.

One of the elements we have mentioned previously are sources. While the process itself has to be methodical in order to gain accurate results, the sources provide the wireframe upon which the interpretation can take place. It therefore essential that the sources are well researched and well documented. For this purpose I like the classification proposed by Dell’Unto et al. (2011), which sees different categories based on accuracy:

  • Reconstruction by Objectivity: sources based on in situ elements, like plans, 3D scans, archives.
  • Reconstruction by Testimony: illustrations, literary sources, notes.
  • Reconstruction by Deduction: elements that can be deduced from in situ remains, but that are not actually there.
  • Reconstruction by Comparison: based on other sites, this is actually quite an important one as a lot of features carry on between remains of the same regions.
  • Reconstruction by Analogy of Styles: especially for decoration, looking at other stylistic elements that have been preserved can help make the whole model look more realistic.
  • Reconstruction by Hypothesis: an essential part of reconstruction, but the most inaccurate.

Of course, the more we go down this ladder, the more inaccurate the sources are. Yet it is by combining all the different sources that we get the finished model. Paradata can help with determining which sources were used for each part of the model, and therefore provide information of the model as a whole.

house6

Fig 3 = Partly completed model of a Greek house, based on plan, excavation reports and site comparison.

In conclusion, there are many sources that can be used when constructing a model and although some are more precise than others, all of them contribute to the final result. If they are applied methodologically and the process is recorded, we can provide an accurate and reliable reconstruction.

Over the next posts I will start looking at SketchUp for modelling, although the ideas will carry over to other software such as 3Ds Max.

REFERENCES:

Beacham, R. C. (2011). Concerning the Paradox of Paradata. Or, “I don’t want realism; I want magic!”. Virtual Archaeology Review Vol.2 No.4 pp.49-52.

Boon, P., Van Der Maaten, L., Paijmans, H., Postma, E. and Lange, G. (2009). Digital Support for Archaeology. Interdisciplinary Science Reviews 34:2-3 pp.189-205.

D’Andrea, A. and Fernie, K. (2013). CARARE 2.0: a metadata schema for 3D Cultural Objects. Digital Heritage International Congress Vol.2 pp.137-143.

Dawson, P., Levy, R. and Lyons, N. (2011). “Breaking the fourth wall”: 3D virtual worlds as tools for knowledge repatriation in archaeology. Journal of Social Archaeology 11(3) pp.387-402.

Dell’Unto, N., Leander, A. M., Ferdani, D., Dellepiane, M., Callieri, M., Lindgren, S. (2013). Digital reconstruction and visualisation in archaeology: case-study drawn from the work of the Swedish Pompeii Project. Digital Heritage International Congress pp.621-628.

Denard, H. (2009). The London Charter: for the computer-based visualisation of cultural heritage.

Devlin, K., Chalmers, A. and Brown, D. (2003). Predictive lighting and perception in archaeological representation. UNESCO World Heritage in the Digital Age.

Ducke, B. (2012). Natives of a connected world: free and open source software in archaeology. World Archaeology 44:4 pp.571-579.

Hafer, L. and Kirkpatrick, A. E. (2009). Assessing Open Source Software as a Scholarly Contribution. Communication of the ACM Vol.52 No.12 pp.126-129.

Hayashi, T. (2012). Source Code Publishing on World Wide Web. International Conference on Advanced Information Networking and Applications Workshops pp.35-40.

Johnson, D. S. (2009). Testing Geometric Authenticity: Standards, Methods, and Criteria for Evaluating the Accuracy and Completeness of Archaeometric Computer Reconstructions. Visual Resources 25:4 pp.333-344.

Marwick, B. (2016). Computational Reproducibility in Archaeological Research: Basic Principles and a Case Study of Their Implementation. Journal of Archaeological Method and Theory pp.1-27.

Miller, P. and Richards, J. (1995). The Good, the Bad, and the Downright Misleading: Archaeological Adoption of Computer Visualisation. In: Huggett, J. and Ryan, N. Computer Applications and Quantitative Methods in Archaeology. Oxford: Tempus Reparatum pp.19-22.

Richards, J. D. (1998). Recent Trends in Computer Applications in Archaeology. Journal of Archaeological Research Vol.6 No.4 pp.331-382.

Advertisements

About Rob Barratt

Mphil in Archaeological Research at Cambridge Univerity, BA in archaeology from Cardiff University, field archaeologist, technology enthusiast and computer geek. I like writing codes and making fancy models of old stuff.

2 responses to “Part 3 – Sources and Paradata

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: