This project re-works Clair Barnes’ (2015) MSc dissertation. Here is the abstract from Clair’s dissertation.

Statistical methods are increasingly finding applications in new disciplines; one area in which interest in such approaches has increased in recent years is archaeology, and in particular, in archaeological studies of Anglo-Saxon England.

A question currently under consideration in this field is whether any evidence exists that buildings in settlements dated to the early Medieval period may have been planned according to a perpendicular grid system. Assessment of the features of a site of interest, and any spatial or angular patterns contained therein, has until now typically been carried out by visual appraisal of transcribed site plans.

We propose a method by which a JPEG image of an archaeological site of interest may be converted into a set of points representing the locations of post-holes that once formed part of the support of large structures such as walls, buildings and fences. Defining the orientation of the post-holes by the direction in which its nearest neighbour lies, we are able to test objectively whether there is any evidence that larger features share a common orientation, and to assess whether a similar grid orientation is shared globally across multiple regions of the grid, or found only locally in smaller regions.

Necessary preparation

Here are the steps needed to prepare a Kubuntu computer system to run the resulting code.

Preparation of Kubuntu environment

Working in the bash terminal:

please apt-get install libssl-dev
please apt-get install libcurl4-openssl-dev
please apt-get install libgeos++-dev

The geos software suite is required by the AS.preprocessing package, in order to load the rgeos package.

Preparation of R packages

Install devtools package using, e.g., Rstudio. Similarly install package fpc. Then load three packages from Clair Barnes’ GitHub repositories using the following R code.

library(devtools)
install_github("ClairBee/AS.circular")
install_github("ClairBee/AS.preprocessing")
install_github("ClairBee/AS.angles")

Preparation of Genlis image

The initial image cleaning requires interactive input! Carry out the following within R:

library(AS.preprocessing)
genlis <- import.map("Genlis.jpg", threshold = 0.2, plot = T)
get.scale(genlis)

responding to prompts appropriately:

> get.scale(genlis)
Is the highlighted object the map scale? (y/n) > n
[1] Please click on the scale marker...

Click on marker! A further response is required, this time numerical, followed by affirming that one wishes to continue.

What is the length, in metres, represented by the map scale? > 10
Do you want to rescale the map coordinates now? > y
[1] New object 'rescaled' created containing rescaled raster.

Now proceeed with

genlis.NS <- get.NS.axis(rescaled)

responding again to prompts:

[1] Please click on the N-S marker...
# Click on marker!

Finally add information to data structure.

genlis <- NS.marked

save.features(genlis, "Genlis-Initial-Cleansing")

so that the Rstudio script can commence with

genlis <- load.features("Genlis-Initial-Cleansing")

Bibliography

Barnes, C. (2015). Statistics in Anglo-Saxon Archaeology. MSc dissertation, Department of Statistics, University of Warwick. 82 pp including 5 appendices.