Contrastación de Hipótesis

With new set of components and a basic plan in mind, the coding for the device now needed altering to reflect the changed nature of its performance. For a full breakdown of this coding, as well as technical data of the device, see Appendix 1.

This first stage of coding was subsequently refined following on from the Bryn Celli Ddu pilot study (see chapter 5.1), where minor tweaks were made to default settings variables such as gain, in order to have truer hue readings.

62 3.3.3.3 Construction

Fig 7. Orac V2.1 - now waterproof and dog proof. P Foreman March 2016

After the initial prototyping phase, the first version of the device was constructed for testing at a pilot study at Bryn Celli Ddu, Anglesey (see chapter 5.1). This construction phase took the components from the prototyping board seen in figure 10, and permanently soldered them in place on permanent circuit boards along with a battery module and LCD screen, meaning the device could function in the field without use of a laptop.

3.3.3.3.1 Challenges and adaptations in construction

As the first stage of the research design, the pilot study naturally highlighted a series of challenges that form valuable feedback and opportunity for finessing of the methodology.

The main challenges identified were issues with the prototype colour sensor, issues with the removal of lichen on site, and issues with the recording of data.

Although the initial results gave recognisable values that did show a difference between pale, dark, and reddish material on site, the results were “muddy” – not as precise as

expected for a device as sensitive as the hardware specifications suggested, and always on the darker end of the spectrum. This could be explained by two factors; 1, that the mapping of RGB values from 16bit to 8bit has made the values less accurate and more prone to

63 giving dull results, or, 2 - the wooden emergency casing for the device meant the sensor was slightly too far from the surface of the material being measured.

These could both be addressed by further adaptations to the device, most notably creating a custom thin plastic casing which will allowed the sensor to be much closer to the material surface, but also the possibility of tweaking the parameters the colour sensor works upon. At the beginning of the code that initialises the sensor, there is a default setting for gain – which is, in effect, the white levels within the colour values it records. Altering the gain will make colours lighter or darker depending upon how the setting is changed – by raising the gain level, a lighter reading could be achieved, which may resolve the “muddying” issue.

As with most uncleaned rock surfaces exposed to the elements, the stones of Bryn Celli Ddu are covered, in various degrees, by lichen of numerous species. These manifest in a variety of colours and can cloak the actual colour of the stone beneath. During this pilot study removal of small patches of the lichen was attempted, using water and a soft toothbrush.

However, it was soon obvious that this was not a simple task, and that the attempt to remove lichen actually spread staining further – usually as a faintly green mark on the cleaned area, that returned a slightly green RGB result with the sensor. It soon became apparent that a firmer approach was needed, perhaps with a hard bristle brush – which then raised concerns on the damaging of the rock surface. Short of power washing with pressure washer, it would be very difficult to remove all traces of lichen. It was decided instead to attempt to locate portions of the rock that were least affected and to take readings there, making careful note on each stone’s recording sheet if there was the suspicion that any particular reading was polluted by lichen.

As has been previously noted, the original prototype was made into a wooden case, for ease of temporary construction and to develop an appreciation for the general reliability and durability of the components and wiring before the device was placed in a more permanent home. As a custom plastic casing would take some time to be delivered, a short term replacement was made from materials to hand, and so a small wooden case was constructed. This contained the components securely and was robust in nature, though clumsier in appearance and less convenient than a more streamlined plastic casing would be. The advantage of wood as a material was that it could be easily drilled to allow the switch and colour sensor to fit correctly to the exterior, but the disadvantage was that the wood was slightly too thick to allow the sensor to be as close to the stone surface being measured as desired.

A further issue, highlighted by repeated delays caused by poor weather, was the face that the device is not waterproof or even splashproof. The sensor itself is by necessity open to

64 the elements in order to be placed close to the stone and measure colour accurately – tests involving thin, clear plastic did show slight alterations in RGB values and were thus rejected.

However, as weather conditions can never be guaranteed, it would be valuable to make the device as weather proof as possible, and so, further iterations should explore options to protect the sensor whilst still allowing it to record data without compromise.

Otherwise, performance was acceptable. Although battery power failed after a few hours, the interior was easily accessible to replace the 9V batteries into the simple clip. The screen was clear and easy to read, and the wiring was reliable, requiring no repairs or inspections over the course of the study. Improvements decided upon for the next iteration improved

portability, weatherproofing, performance of the sensor, and battery life, as follows;

1. A custom designed case that accommodates all components safely and securely, that retains the feature of being easily accessible to enable battery replacements, any emergency repairs, and inspection of the device,

2. Covering the sensor with a material that will not affect the fidelity of the readings, 3. A material thickness of not more than 3mm above the surface of the colour sensor, to

optimise its performance, and,

4. A further 9V battery clip, which should extend the time between battery changes and reducing the number of times access into the device is needed in the field, during which the device vulnerable to damage through dust and moisture ingress.

Though the recording sheets proved broadly adequate for noting the key details of each stone, the sheer volume of sheets (over 100 for Bryn Celli Ddu) was unwieldy in the field, especially in the typically inclement blustery Welsh weather. As the sensor device was bulky, it became necessary to put it down in between each reading and record it, then put the notes down, take a second reading, pick the notes back up again; repeated over 100 times this was time consuming and not always convenient, especially when there were numerous other visitors at the site who may have inadvertently damaged the sensor when it was placed on the ground during physical recording of results.

To avoid this issue, a tablet or phone with access to an offline version of the results spreadsheet is necessary, with a wrist strap so it does not require picking up and placing down regularly. There should also be an increase of data recorded from two to three repeats, to improve the accuracy of the colour average and to further ensure the sensor is giving consistent results.

65 Fig 8. - ORAC on location at Calderstones, as shared by their social media accounts.

In order to achieve a daylight reading with the recording device, modification was needed. A simple daylight blue gel, of a type frequently used in photography to get a daylight effect when shooting images with bright lighting, was fitted over the LED and a separate set of readings taken. The results were interesting; whereas the white LED gave readings that were more yellow than observed by the human eye, the ones under daylight gel were closer to their apparent red colour, though with a blue tinge that stubbornly refused to be adjusted for even with tweaks to gain, time of recording, and physical distance between the LED and the blue gel. It also took a significant amount of time to record readings six times over for each stone - three white LED, three “daylight” - which will not be practical at sites with larger numbers of individual stones, particularly those where access is time limited.

Going forward, therefore, the daylight readings were not attempted. Though it would be ideal to have a record of something that approaches the “original” daylight reading, this technical solution does not come close enough to make an accurate simulacra of daylight to function as a fitting recreation of the stone’s “true” colour. Rather than depict a colour close to that first experienced by the Neolithic stone seekers, it would simply be another layer of artificial,

“born digital” data that would not approach even an approximation of the original assemblage of colour-aesthetic-meaning-choosing inherent in the construction of the monuments studied in this research.

66 3.3.3.4 Rationale for open source software

The Arduino range of devices, peripherals, and documentation is one of the most popular home computing and prototyping platforms in use today (arduino.com 2018) - and one of the main reasons for this is the fact that it is open source. As stated previously in this

methodology, the professional tool to conform to the same function as ORAC would be in the region of ten times as expensive to purchase - and comes with the inherent black-boxed, user separation from comprehension of function and performance inherent with all pre built consumer IT solutions. The flexibility to conceptualise, design, prototype, and construct in affordable stages is a significant benefit, particularly in a research project such as this one where objectives are narrow and specific, and results required to be repeatable and quantifiable.

Open source software and hardware is not merely an affordable and flexible IT solution, however - it is also the source of a significant community of free, welcoming, and helpful expert and enthusiast advice - available freely online through the use of web forums, social media platforms like Reddit, and the support services of the Arduino team themselves. For any problem or issue, it is almost guaranteed that someone has come across it before and has solved it - often a quick Google search will solve a problem easily and cheaply. This community of immense value to postgraduate researchers looking for support and guidance often in isolated, non-standard working hours situations. As one of the key future goals of this research is to develop a crowdsourced initiative to collect massive stone colour datasets (see chapter 10.3), access to these welcoming and free communities means that any group wishing to take part - from academic to school coding club to adult learner training facilities - can find friendly and accessible help with ease.