Computerised bone templates as the basis of a practical procedure to record and analyse graphical zooarchaeological data

This presentation introduces a practical computer procedure for recording graphical skeletal data, often bone fragmentation and modifications such as butchery marks. Utilising a computer based digital image template in conjunction with a basic graphics software package, a process for creating the image and synchronised line templates for the individual skeletal elements is described together with the recording of graphical information. A number of further suggestions of the potential uses of computerised templates for zooarchaeological applications are made together with further development of the approach. Envisaged as an additional tool available to the zooarchaeologist the presentation is made specifically to invite comment and criticism on the approach and seeks suggestions of other useful facilities that such an approach could incorporate. To demonstrate the approach described, a short PowerPoint accompanies this presentation and to enable interested persons to carry out further evaluation and assessment of the approach on their own computers, example templates and guidance notes are available to allow examination of actual templates and the working of some simple routines associated with the approach. These are seen as an intrinsic part of this presentation as a written description can only go so far in introducing a computer application or procedure. Introduction Standardised bone templates for the recording of graphical zooarchaeological data, together with computer applications, are generally recognised as useful for the handling of zooarchaeological data and are regularly mooted as a way forward. However, like all computer applications, there is often a significant requirement for the planning and development of a system or application which is difficult to justify for a single project or small organisation with limited resources. A level of computer application currently takes place but this is generally for recording and handling basic data, often in personal systems or such as * Master program for Biological Archaeology, Bradford University, Inglaterra. E-mail: [email protected] Revista Electrónica de Arqueología PUCP Vol. 2 Nro. 1 Marzo 2007 the York system (Harland et al. 2002) which is an example of a database that is available for such use. Computerised recording of graphical information, such as fragmentation or surface modifications, is not generally practised when recording zooarchaeological data. Popkin (2005) has established a series of standardised line templates which, although held in a digital format, are essentially for printing and use as a paper-based recording system. Marean et al. (2001) and Abe et al. (2002) did pioneer a truly computer based system for the recording and analysis of fragments and butchery marks. This system, linked to a database, allowed computerised recording of fragments and butchery marks and incorporated the analysis of fragmentation to establish a MNI (Minimum Number of Individuals) and butchery mark distribution. However the system, based in ArcView (ESRI 2005) mapping software, could be viewed as expensive and complicated to implement. Additionally the application was developed in an early version of ArcView (3.3) using the programming script ("Avenue") for its routines and it has now been superseded by the later versions of the ArcView software. Based on ideas established in my undergraduate dissertation which specifically examined the application of the Marean and Abe systems (Abe et al. 2002; Abe and Marean sf.; Marean et al. 2001) this presentation presents a simple, practical procedure for creating standardised graphical templates together with their complementary line templates. Utilising a widely used graphics software package the approach potentially advances the handling of zooarchaeological data significantly and forms the basis of a practical graphical recording system for researchers and those who handle and analyse this type of material. Details of the system and its application To introduce the application described in this presentation there are a number of concepts and conventions that need to be explained, these are set out below but are also demonstrated in the evaluation material that is available for those who are interested. The template (Fig. 1a) An individual template is composed of a set of digital images of the particular skeletal element all set out within a single screen. These templates are the basis of the application and all the graphical data, such as individual fragments and any associated butchery marks are recorded in relation to the standard template of the particular skeletal element. The line template (Fig. 1b) Closely associated with the digital image template is a simple line template. This is essentially a layer but is incorporated in such a way as to be interchangeable with the image template so that it can be used to make the fragments or butchery marks clearer to see on screen or when they are printed out. Given that a high level of bone detail is provided by the images, the line templates are extremely simple and only provide a basic outline to the bone. Layers All the work is done with layers that are placed above the image and line templates. The layers would contain detail of a fragment or identified butchery marks on the particular bone and are best likened to transparent sheets that contain various bits of the graphical data. These layers can be copied to record data, saved separately, added to the stack on top of the template as required and removed from it. Additionally they can be "switched" on and off as required or have their transparency varied to aid examination or interrogation of the previously recorded data in them. How the graphical data is recorded and stored Before the graphical data can be used for analysis it has to be recorded in its own layer which is then saved as a separate file that can be recombined to examine various groupings Revista Electrónica de Arqueología PUCP Vol. 2 Nro. 1 Marzo 2007 Fig. 1a. Example of the image template. Fig. 1b. Example of the line template. Revista Electrónica de Arqueología PUCP Vol. 2 Nro. 1 Marzo 2007 of the data for analysis. To do this new layers are created over the template and the fragment drawn in one and the butchery marks (if any) in another (as fragments and such as butchery marks may be examined separately they are stored separately); the two layers (for example butchery and fragment) which together record the fragment are saved as two separate files both identified as the same fragments so they are always related. Using the recorded data The supplementary evaluation material demonstrates both of these uses of recorded data. Once the data has been recorded and the individual layer files saved (fragments and any associated surface modifications) they can be recombined over the templates in groups, for example to examine all the butchery evidence on the left femur those particular layer files are then added over the left femur template and the distribution pattern is immediately shown. Similarly fragments can be combined and another way of determining MNI applied Key criteria in developing this application were flexibility, functionality and cost. The application, its templates and their potential for use to record and analyse graphical zooarchaeological data had to recognise the individuality of potential users who may have different requirements. As such it is conceived as an addition to the zooarchaeologist's toolkit for examining archaeological remains which after recording the graphic information could be used to examine data in a number of different ways to explore the potential for understanding and interpreting that material. There has been no intention of "locking" the application into a specific programme, programming script or language so individual users may apply the templates and develop their use in the most appropriate way for themselves, thereby maintaining maximum flexibility for the future. Development was carried out using Pro Paint Shop Pro (www.jasc.com), a widely used graphics software package which is one of a number of graphics packages that are on the market today; all perform similar functions and as such the templates and application are potentially transferable to a user's preferred graphics software. The use of Paint Shop Pro for development and demonstration has been based solely on the author's personal preference. It was anticipated that printing for hard copy file records or to incorporate into reports would be particularly important both of the templates on their own and with data incorporated; to maintain flexibility, templates have been made large so that a whole template, individual bones or parts of a bone may be printed without loosing quality. Methodology: Creating templates To create the image template, the individual skeletal elements were photographed from each of the directional views (i.e. anterior, posterior, lateral and medial together with proximal and distal views if applicable). A digital camera was used for the purpose (Fuji Finepix S602 Zoom digital camera without any modifications or special attachments) creating a standard JPEG format image, 2832 x 2128 pixels in size with 72 pixels per inch resolution; these images were then downloaded into a personal computer. All manipulation and template creation was carried out using Paint Shop Pro 5 (Jasc Software 1998), firstly using the software's suite of selection tools to select and "lift" the bone out of the digital photograph. After checking and neatening the individual images, their size was standardised and then they were incorporated into the single composite template. Finally the necessary labels were added to the template. All file formats used were Paint Shop Pro's own format with a "psp" extension which makes these particular files usable only in the Paint Shop Pro programs. However as stated earlier the files can be converted to other graphic program formats. Revista Electrónica de Arqueología PUCP Vol. 2 Nro. 1 Marzo 2007 The use of a computer has particular advantages when creating digital image templates; for example, for the sided skeletal elements only one side was photographed and incorporated into a template. To create the template for the opposite side the software's "mirror" function was used to create an exact copy for the opposite side (Fig. 2a y 2b). Another example is the combining of parts of images to digitally "repair" the image of a bone. This was specifically used for the tibia image; both bones had some erosion of their proximal epiphyses (Fig. 3a), by copying the patella area from one image to the other a complete bone image could be created for use as a template (Fig. 3b). Once the image template had been created, the graphic program's selection tools together with its features for edge definition, selection tolerances and merging were used to define an edge to each bone image in the template. By creating a line from this edge and blanking out the image, a perfectly aligned line template for the bone was created. This was incorporated into the basic template so that it could be used interchangeably with the image. Methodology: Recording fragments and butchery marks and creating data records Working within a blank layer, the fragment outline is drawn over the template on all the views as appropriate. This layer is then saved in a directory specifically for all the fragments (as opposed to another specifically for the butchery data or a general directory) so the files are grouped together and may be easily identified and recovered at a later stage as may be required for analysis. Familiarity with the program and the layer format means a number of shortcuts to the recording process can be adopted to speed up data recording. For example, using a copy of the line template as a base for a fragment to redrawing bone outlines and the copying of previously recorded, similar fragments, modifying them as necessary and then resaving as a new fragment file. Figures 4 a, b and c illustrate this procedure and the accompanying evaluation material demonstrates the process specifically. How the templates can be used and the computerised approach Computerised, standardised templates together with layers open up a number of possibilities for researchers; at the very basic level of use the templates can still be printed out whole or in part to form the basis of a hand recording system and the templates can produce large quality prints if necessary. Also, given a range of templates being available and the level of detail the images themselves provide the templates could also help in the examination and identification of the skeletal material should actual reference material not be available. However the primary purpose of the application as presented and described here is as a basis for a digital recording system which can then be used to interrogate and analyse the information much more easily than has been possible with paper based recording systems. Once individual data files have been brought together and aggregations have been created, separate project files can easily be created and retained as a permanent record or printed out for inclusion in reports. Particularly important aspects of graphic data analyses is the examination of butchery mark distribution which is carried out successfully "longhand" (O'Connor 2000: 47, fig.5.4.) or as presented by Abe et al. (2002) in a more sophisticated example. The other is as originally demonstrated by Marean et al. (2001) where MNI may be determined from the analysis of fragmentation. The accompanying evaluation material demonstrates how similar results may be achieved using this, albeit simpler procedure. The organised storage and ease of recovery, the transportability of digital templates and data itself also opens up opportunities for standardisation, comparison of compatible data and centralisation of specialist research. Revista Electrónica de Arqueología PUCP Vol. 2 Nro. 1 Marzo 2007 Fig. 2a. The original image of the left femur (anterior view). Fig. 2b. The right femur image created using the software’s mirror function. Fig. 3a. Both tibias had errosion present. Fig. 3b. By transposing the patella area from one bone to the other a complete template image is created. Revista Electrónica de Arqueología PUCP Vol. 2 Nro. 1 Marzo 2007 Fig. 4a. Template with fragment and butchery marks recorded in layers above. Fig. 4b. Separate layer with fragment details as saved. Revista Electrónica de Arqueología PUCP Vol. 2 Nro. 1 Marzo 2007 Fig. 4c. Separate layer with butchery details as saved. Future work and development This paper and its accompanying evaluation material introduces an application that clearly has a significant zooarchaeological potential. However it is not presented as the final solution and the author recognises that there is further development work required, both to get the basic application fully operational and to explore its breadth of potential for examining and analysing data that is essentially graphic in nature. Not least is the creation of the basic image templates to establish the foundation for recording as well as any other developments that may arise from this approach to handling graphical data. One important aspect of any computer application is its testing and refinement under "field" conditions. Although the author has undertaken tests using small and experimental assemblages that have been available, there is a need to challenge the approach so that its limits may be determined and to identify particular requirements or areas of further development. The author therefore invites comment and suggestions on the content of this presentation and evaluation material or suggestions for opportunities to apply its use to a large archaeological assemblage. Supplementary files for evaluation To demonstrate the procedure described here a short PowerPoint presentation is available for download. For those interested in evaluating the approach further, material is available to run some practical exercises on your own computer. This material is designed to demonstrate the template and layer principle, how an individual fragment and associated butchery marks may be recorded, the aggregation of individual files to analyse the fragmentation or distribution of butchery marks and the calculation of an MNI from a fragmentation analysis. However, as the content of this material is principally compressed image files they are too large to make it practical to download over the internet. However if you would like to continue evaluation of this approach please contact the author with your postal address and a CD containing the evaluation material will be posted to you. Revista Electrónica de Arqueología PUCP Vol. 2 Nro. 1 Marzo 2007 Further evaluation material includes: Guidance notes and instructions (introduction, examination and simple routines). Guidance notes and instructions (introduction to recording the graphic data). Pre-prepared template with demonstration layers to introduce the concept. Previously recorded data fragments and butchery marks. Pre-prepared template incorporating data layers to apply the procedure to zooarchaeological material. Example image templates for examination and recording practice. You may wish to download the guidance notes and instruction first which are WORD documents to read them before deciding if you want to continue with the practical part of the evaluation. Requirements to undertake the template evaluation In order to run the evaluation material you must have access to a modern personal computer with as much RAM as possible and a high performance processor as performance is related to the amount of memory that the computer has on board and its processing speed. In particular, when loading a file, you may encounter pauses in the program as the computer sorts out the memory and changes files between the different types and its hard disc so that layers can be worked on screen. Particular software requirements The evaluation material has been designed to run on the latest version of Paint Shop Pro (X version 10). If you do not have access to this software, a free download of a 30 day evaluation copy is available from www.corel.co.uk. Paint Shop Pro X will only run in conjunction with Windows 2000, XP or later operating systems. If you have any problems downloading the files please contact the author. Acknowledgements The author would like to recognition all those individuals who have provided their help, assistance and encouragement in the development of this presentation and particularly the obtaining of materials, technical advice and the reading and testing of draft material and proofs. Revista Electrónica de Arqueología PUCPVol. 2 Nro. 1 Marzo 2007 ReferencesAbe, Yoshiko, Curtis W. Marean, Peter J. Nilssen, Zelalem Assefa y Elizabeth C. Stone2002 The analysis of cutmarks on archaeofauna: A review and critique of quantificationprocedures and a new image analysis GIS approach, American Antiquity 67(4), 643-663, Washington, D.C. Abe, Yoshiki y Curtis W. Mareans.f. Bone entry GIS and Bone Sorter Manual: for recording, sorting and analyzing bonesusing GIS, State University of New York, New York. ESRI2005 http://www.esri.com/ Harland, Jennifer F., James H. Barrett, John Carrott, Keith Dobney y Deborah Jaques2002 The York System: An Integrated Zooarchaeological Database for Research andTeaching, Internet Archaeology 13. http://intarch.ac.uk/journal/issue13/harland_index.html Jasc Software1998 Paint shop pro 5: User guide and tutorial, Digital Workshop, Tewkesbury. Marean, Curtis W., Yoshiko Abe, Peter J. Nilssen y Elizabeth C. Stone 2001 Estimating the minimum number of skeletal elements (MNE) in zooarchaeology: areview and a new image-analysis GIS approach, American Antiquity 66(2), 333-348,Washington, D.C.