Tag Archives: scotsburn

Experiments using a Quadcopter for Archaeological Aerial Photography

by Alan Thompson (NOSAS)

Introduction

I’ve had my Quadcopter for over a year now, had great fun flying it, and have produced many interesting images.  I recently showed a selection of images at a NOSAS evening, and was asked if I would write this blog and share some of the things I’ve learned along the way.

Of course the pictures are what it’s all about and even if you’re not interested in my comments, I hope you enjoy looking at them.

Background

Inspired by some of the wonderful aerial photos (APs) I’ve seen (for example on Canmore) I have long thought how good it would be to be able to take such pictures of our own archaeological sites.

For several years I have been interested in photogrammetry and experimented with that, especially of rock art where the production of a 3D surface and use of computer generated lighting and shadows can give some great effects.

In 2013 I began to investigate kite aerial photography (KAP) but the possibility of using a Quadcopter also emerged and I realised that technology and prices were moving so quickly that it might be a better option.  In early 2014 I decided that the only way to learn was to buy one.

The Quadcopter – getting ready to fly

Most amateur Quadcopters are sold with very wide angle cameras, with the intention of video recording, and also providing a pilot’s view (called first person view or FPV).  This is less than satisfactory for archaeological aerial photography, and so I bought a Quadcopter without a camera, with a view to fitting my own.

The camera is obviously critical, and it needed to be light (ideally <300g including battery), robust, of good enough quality, and with an interval timer.  Unfortunately I could find no such camera.  All those with interval timers are heavier, for example those used for kite aerial photography.  A solution can however be found in that a group of people spend their time hacking the software of Canon cameras (google CHDK) and provide a hacked version for some models which enables an interval timer to be run.

Having bought and hacked my camera and got the interval timer working I had to fit it to the Quadcopter.  The main problem is the high frequency vibration from the rotors which renders the pictures useless.  A suitable anti-vibration mounting was needed, all within the weight limit.

Next, to prepare for the first test flight.  The web (YouTube) is full of videos of alarming crashes and fly-aways.  The Quadcopter instructions are daunting saying that a first flight should be from the middle of a large field, with no wind and no people about.  There is also the matter of insurance (it could certainly hurt someone badly), and the possible need for a CAA licence.  The regulations here are changing quickly but at present as a hobby flier I can insure through the British Model Flying Association (BMFA), and (unlike a professional archaeologist) have no need of a CAA licence provided I fly within line of sight, avoid certain areas (eg near airports) and limit the height.  I would again emphasise that this is all very much in the news and changing and my observations here will quickly be out of date.

Quadcopter flying

The first flight is bit nerve-racking, but set to auto mode the Quadcopter uses its own GPS and compass and is set so that (more or less) if you let go of the controls it just hovers where it is.  Flying in this mode is reasonably straightforward.  I have not dared try any of the advanced modes as yet.

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Excavations on the Tarbat Peninsula: Scotsburn (Iron Age Broch or Dun) Part 2

By Vaidutis Žutautas (University of Aberdeen)

Just above the left bank of steep wooded ravine of the Balnagown river, remnants of a prehistoric dun (NH77NW 6, NH 7148 7616) sit on the sloped eminence surrounded by a complex of structural features, arguably belonging to it. The site has been known for a long time, as it still stands prominently and it is likely that it has not been disturbed by agricultural activities throughout centuries, although some possible robber trenches can be seen on the E side of the dun wall. Prevailing arguments suggesting that the roundhouse could carry the title of ‘a broch’ were usually subjected to narrow over-surface interpretations by only taking into consideration structural features such as the diameter of the house (13m), wall thickness (~6m on the surface) and its elaborate compounds that skirt the dun. However no comprehensive evaluation has been done since 1968 when OS did a basic descriptive survey and designated the structure as a dun.

In order to expand the distributional scope of the late prehistoric structures in Tarbat peninsula and its environs, the team of archaeologists from the Aberdeen of University has targeted Scotsburn Dun in seeking to evaluate the underlying archaeology. A permission to locate 3m x 20m trench and extract effective dating material that would provide a chronological framework for the site was given by Historic Scotland Scheduled Monument Consent. Additionally, to answer perhaps the most intriguing question­- whether the structure is a broch or a complex dun – authorisation was given to uncover the roundhouse wall and identify its external morphology that would allow drawing assumptions regarding its structural classification.

Since this excavation was ongoing along other two digs in the area (Cnoc Tigh and Tarlogie Dun), the logistics were relatively subordinate especially in terms of people on the site. At least two archaeologists were working at Scotsburn with a kind help from volunteers living in the region. Yet even said that, the dig has not been crowded and therefore dealing with exceptionally complex archaeology and nearly 40m3 of deposited rubble extended original ten day dig to a four and a half week mattocking paradise.

Realising the complexity of the site on the first day, it was decided to open 2m x 20m trench stretching NW-SE encompassing area between the roundhouse and the enclosure wall and another two earthworks giving another 6,8m extension for vegetation, top soil and limited latest collapse deposit clearance from the dun wall. Unsurprisingly, it has been a highly demanding task to define structural features and reach occupation horizons by removing tons of collapsed stones; this process took nearly two weeks mainly allocating labour in two areas: a) between the roundhouse wall and the enclosure wall, and b) between the enclosure wall and the first earth bank.

Scotsburn full trench

Aerial picture of the entire trench showing mid-excavation.

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Excavations on the Tarbat Peninsula: Scotsburn (Iron Age Broch or Dun) Part 1

Mid Excavation Report by Oskar Sveinbjarnason (University of Aberdeen)

The excavation at Scotsburn House aims at dating the occupation as well as trying to discern if the site is a broch or a dun.

Outer wall face of Scotsburn "house" with Roland.

Outer wall face of Scotsburn “house” with Roland.

A single trench 20m long and 2m wide was placed over the building wall and extends northwards over four rampart banks. The round house wall has been revealed but it has not shown yet if it is a broch or a dun. The ramparts have so far shown a nice stone facing. The site is getting more complex as “new“ walls have been uncovered in the trench. The relationship between these walls and the ramparts and ditches is being investigated.

Photo from the trench with Leaf and James.

Photo from the trench with Leaf and James.

The lower left corner of the picture shows one of the banks. Behind Leaf and James is another bank and towards upper right corner is the Scotsburn house wall.

Following Oscar’s report an iron age road surface was uncovered in this ditch.

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