Photogrammetry and RTI

Photogrammetry and reflectance transformation imaging (RTI) are techniques for creating interactive spatial images. We are using these techniques to create representations of Blackfoot cultural heritage, as well as in workshops and art-making.

Photogrammetry is a photographic process that creates an extremely dense and precisely textured 3D model.

photographs that are used to create a 3D model
Software uses the data from the photos to generate a textured 3D model.
Screenshot of photogrammetry software
Each ring is made up of a series of photographs taken around the object at different angles.

The 3D models on were created by Tom Allison, 3D artist and Associate Lecturer at Central Saint Martins.

The top and bottom of an item are usually photographed separately. The two halves are processed in the software to generate models and are then joined together to appear as one cohesive object. Some soft or semi-transparent materials, like fringe and hair, are very challenging to image using photogrammetry, which prefers solid surfaces. As a result, some of the fringing and hide had to be manually modelled based on photographic references to create a truer image of the original item.

RTI is a photographic method that creates an interactive image that can be relit from multiple angles to reveal detailed surface information. The resulting digital file can be digitally interacted with as if with a raking light, often revealing details difficult to see in natural lighting conditions.

Hundreds of photographs with a moving light source are used to make the interactive image.

Cultural Heritage Imaging is a great resource for learning about photogrammetry and RTI. They offer free software for building and viewing RTI projects.