Over the summer Kieran and I became involved with a little bit of work for the Hidden Heritage Project. The community project is based in the isthmus area between Arrochar and Tarbet and aims to investigate the heritage of the area from prehistory to modern-day. We were called in to help record one of the post-medieval graveslabs in the Ballyhennan Graveyard which potentially dates as far back as the 16th Century. The stone sits in a fairly shady setting under some trees in the old graveyard and in daylight it is very difficult to make out any of the carving on the surface of the stone – it could quite easily be mistaken in passing for a plain, quite unremarkable slab. However, as Iain Dick’s photographs taken earlier in the year had revealed the slab was in fact highly detailed.
We took a drive up to meet one of the project leaders Sue Furness at the graveyard and amidst a cloud of very determined biting midgies Kieran did the honours and began capturing the images for a detailed photogrammetric survey of the slab. Photogrammetry simply involves taking a series of overlapping photographs from different angles and using computer software such as Autodesk 123D Catch to stitch them together to produce a three-dimensional textured model of the subject. It was our method of choice as we felt it was the quickest and most accurate way of efficiently creating a detailed record of the slab which could then be manipulated digitally in software such as Autodesk 3DS Max (rendered with Vray) to bring out detail by playing around with the lighting in a virtual environment.
Once the photographs had been processed and the resulting 3D mesh tidied up I began work on an animation which would bring out the detailed carving on the slab. After a few experiments I decided the best way to achieve this was to animate the stone with a moving light source, almost like a time-lapse, in order to bring out the relief from different angles.
In addition to the animation, Kieran produced some really nice un-textured orthographic projections (in other words 3D views of the slab in 2D which allow accurate measurements to be taken), re-lit to bring out the detail and I spent some time drawing (with my actual hands not digitally with a graphics tablet – this is a rare occurence these days!).
This wee project proved to be a great example of the different ways it’s possible to document and visualise a subject and the different benefits from each. Photogrammetric survey allowed us to create a textured solid mesh model of the graveslab which could then be re-lit in a virtual CGI environment to experiment with the best ways of bringing out the detail. The resulting animation reveals the detail of the slab in a dynamic way as the light moves across the surface of the carvings and expresses the three-dimensional nature of the slab from different lit perspectives. The photogrammetry also allowed us to produce measurable orthographic images of the graveslab which in turn helped to inform the traditional hand-drawn illustration.
You can read more about the Hidden Heritage project on their website or follow them on facebook which is always updated with the current goings-on of this fantastic community project! If you want to read more about the graveslab itself and see the visualisations again (why wouldn’t you?!) you can explore their interpretation pages here.