In the next few steps of this tour, we will show you different slices of the CT scan. These show a greyscale density based image of the interior of the whale.
Investigations into cultural heritage objects are most often focused on external features. While this is not surprising, simply due to ease of access, the interior often holds as many secrets at least! From traces of toolmarks that inform us about studio practice and making processes, to fingerprints that facilitate authenticating objects: unveiling an artwork’s internal structure may help uncover a myriad of aspects of an artwork previously hidden from the eye.
In the past years, X-ray Computed Tomography (CT) has been used to visualise the interior of objects in 3D. For example within the NICAS and NWO funded Impact4Art project by CWI and Rijksmuseum. A CT scan is comprised of hundreds of individual X-ray images taken from different angles, which are then combined using tailored reconstruction algorithms into a 3D representation of the object. Such datasets are often investigated by slicing through the 3D representation, providing the researcher with a 2D image as if the object was cut through at a given point. This image, a black and white image of relative densities in the object, allows us to identify and investigate internal features.
A drawback from analysing CT data using such slices, is that most museum professionals are trained to examine objects in 3D, rather than 2D. It can be hard to interpret and extract certain features from 2D slices and directly relate them to the 3-dimensional object.
Therefore, within the IntACT project, we set out to solve these issues by providing a better way of inspecting CT data for museum professionals. To accomplish this, we wanted to:
1. Visualise the CT data interactively in 3D (with an option to still enable 2D slices alongside);
2. Combine 3D surface scans of the object with the CT data, to provide the real surface colour of the object.
In this online representation, we focus on the second goal of the project.
By combining surface scans and CT scans, the data becomes more easily and intuitively explorable. That is to say, the object now exists virtually in 3-dimensional space, with its real colour information on the outside, and the CT data on the inside! This facilitates associating observations on the exterior surface to features in the internal CT data - and vice versa.
In the next steps of the tour you will see a few slices that have been registered to the 3D model of the whale. This allows us to look at the interior, while also having the threedimensional shape still visible. This helps object experts to interpret the relationship between what can be seen on the outside and what is on the inside.