Photogrammetry is the process of making measurements from photographs. Scientists can use photographs to create a digital model of an object or location. There are many different reasons why palaeontologists make digital models of specimens, from studying small and hard-to-see details, to making exact replicas (casts).
Although we have the majority of this Daspletosaurus torosus skull in our collection, it is too fragile to piece back together. When a specimen is too delicate for display, we usually create a cast. However, most of the pieces of this skull are too fragile to withstand traditional casting methods.
Our solution was to use photogrammetry to create three-dimensional models of each piece of the skull. We then had these models 3D printed.
Our technicians took multiple photos from different angles of each individual piece of the skull with scale bars. The scale bars ensure accurate measurements when creating a digital model of the specimen.
By taking multiple photos from different angles, our technicians were able to create digital models of different sides of each bone. First, the model is generated as a “point cloud.” Then it is fleshed out to create the three-dimensional model.
The numbers of pictures taken and models made depend on how complicated the shape of the bone is. Two hundred and seventy-seven photos were taken of the pre-maxilla pictured here to build a three-part model that was stitched together to create a digital version of the fossil.
Once complete, the models were sent to the printer to create a 3D-printed cast. This is the first time we have used 3D-printing technology to create casts for display. The technology offers us a new and exciting way to make casts of delicate specimens.
Using models of the individual pieces, we also created a merged model of the skull, and virtually pulled pieces apart to create the exploded side. This formed the design for what the specimen would look like on display. The complex mounting process required the specimen to be suspended in the air to determine the final position of the pieces.
The exploded skull of Daspletosaurus torosus is currently on display in our Fossils in Focus exhibit.