Projection Mapping and Medieval Virtual Reality

PJ Banner 2Over the past couple of months we’ve been examining a range of delivery methods for historic building reconstruction visualisations beyond apps and on-screen video fly-throughs, in particular for museum and exhibition settings. A couple of techniques have been of particular interest, projection mapping and VR headsets. Projection mapping also known as video mapping and spatial augmented reality is not a new technique, it’s been used widely for projecting images and particularly polychromy reconstructions onto real buildings at 1:1 scale for some time. However as far as we can determine it’s been little used in conjunction with 3D printed heritage exhibition models, which is something we thought would be worth exploring. Our intern Romylos created a polychrome reconstruction of the internal south wall of the nave of the St. Mary of Annunciation 3D printed model we made last year for the De Montfort University Heritage Centre to try out the technique. With the assistance of collages at the Heritage Centre Romylos carried out some tests, in situ in the exhibition with a micro-projector to see what the projected polychrome elevation would look like and examine the practical issues of this kind of projection within a live exhibition setting. In low light conditions the overall effect was remarkably effective with an ability to switch easily between alternative polychrome reconstructions within the same 3D printed model. It’s also possible to project video instead of still images and animate the projected surfaces which has a number of narrative possibilities. At a technical level beam divergence does not appear to be a significant issue on sectional models like this where the variation in projection plane is relatively small, nor does transmission loss or diffraction through a layer of 5mm Perspex case cause any noticeably deleterious effects, though focus has to be precise, and the flatter the sectional model the better. Of greater issue are foreground obstructions within the model itself which if not accounted for the in the composition of the projected image will, when illuminated have the wrong surface image and will cast a shadow behind them (e.g. see the tombs and altar to left of model in the image above). Overcoming this requires careful thought in designing the model and the projected images together so that complement one another.

VR headset banner 1 smallFor the same reconstructed church we’ve also been using a Samsung Gear VR headset, to create 3D virtual interiors. It uses a Samsung Galaxy S6 Flat 128 GB SIM-Free Smartphone to deliver the sphere photo / render of the 3D environment and you can have a connected series of locations which you can navigate through using a slider on the side of the set. This is a relatively low cost, accessible and well-understood way for users to engage with VR and delivers a remarkably convincing immersive experience for the cost. The key factor in the experience beyond the content of the image is the screen resolution of the phone, the Galaxy S6 has a screen resolution of 1440 x 2560 pixels (~577 ppi pixel density) which is good by current mobile phone standards, but you’re still conscious that you’re looking at a digital image because although they are small, the pixels are still detectable. It’s very likely that continuing improvements in phone screen resolution will overcome this in the next couple of years just as flat screen technology has done in other applications. As it stands, it’s the immersive 360 degree real-time interaction with the virtual environment which is a significant attraction to users and consequently for heritage visitor experiences that are considering adopting it. From being a novel technology 3-4 years ago, with prices to match VR headsets are now rapidly approaching something that could be described as mainstream, and the technologies comprising its immediate on-site use are becoming much more integrated and mature. Given this we are looking carefully at the methodological and epistemological issues which bear upon how and why to employ these technologies for presenting and understanding heritage buildings, what effects the technology may have upon that understanding and whether other alternatives may be more appropriate in certain circumstances. In particular we are interested in the institutional, museological, operational and interprative advantages that hybridised approaches using both tangible exhibits like 3D printed models and digital assets like 3D VR interiors can bring to heritage interpretation.

About Douglas Cawthorne

Reader in Digital Heritage at De Montfort University.
This entry was posted in 3D Digital Modelling, 3D Printing, Churches and Ecclesiatical, Medieval, Museum Installations, Museum Installations, Projection Mapping, Textures and Rendering. Bookmark the permalink.