Structure from Motion (SfM) is a relatively new and novel ‘machine vision’ software technique that allows us to quickly capture the 3D geometry of static features, artefacts, scenes and objects at relatively ‘low cost’ compared to more established survey methods (Terrestrial LiDAR, structured light scanning etc). SfM uses commercially available handheld digital cameras (DSLR) or in some cases small format camera equipped Unmanned Aerial Vehicles (SUAV) to capture hi resolution/high megapixel colour images of the target feature and/or scene.
Overlapping imagery is processed in desktop PC software or in the Cloud to calculate the ‘position’ of the digital camera in virtual 3D space around the object. Multiple overlapping camera positions are used to create a ‘depth map’ of the subject that exists in 3D space as a ‘sparse point cloud’. A second software run creates a ‘dense point cloud’ similar in resolution and geometry to laser derived surface geometry. Finally the point cloud is meshed to create a continuous surface and the original colour imagery from the camera photos is ‘draped’ over the model to aid visualisation.
Outputs include a final solid 3D model of the feature, 2D orthometric colour imagery and area/volumetric analysis (where control point measurements are available). The models have value as a metric archive (digital reality, conservation through record), an educational/tourism resource (virtual museum/field visit/3D printing), and where features/objects are of similar form/geometry but separated by geography, scientific analysis and research (metric comparisons, condition analysis, virtual research collaborations).
As a value added component, models can now be uploaded to ‘community 3D’ Cloud websites (e.g. Sketchfab.com), visualised, shared and downloaded to PC, tablet and Smartphone, to the local, national and international public, scientific and heritage community.
This technology is managed by and Mr Conor Graham
Lieutenant-General Sir Denis Bernard
Many thanks go to:-
Mr Gavin Glass, Curator of the Royal Ulster Rifles Museum, Belfast for the loan of Lieutenant-General Sir Denis Bernard uniform.