Scanning Stephenson’s Rocket
One of the areas that the Science Museum Group’s Digital Lab has been experimenting with is what we are calling enhanced digitisation.
Given that most of the Science Museum Group Collection is comprised of 3D rather than 2D objects, we have been exploring how we might capture a better representation of our objects than just a photograph, what the impact on our internal workflow would be for different capture technologies and how visitors might access and use these new digital objects.
In the run up to the opening of Mathematics: The Winton Gallery we undertook rotational photography as well as some photogrammetry of smallish objects. One of the challenges we faced with the rotational photography was adjusting the lighting conditions so there was no flare as the object was rotated for photography.
Shortly before Stephenson’s Rocket left the Science Museum to visit the Discovery Museum in Newcastle (for the Great Exhibition of the North) and the Science and Industry Museum in Manchester, we decided to carry out a very high resolution scan of this iconic locomotive.
Working with ScanLAB — who previously scanned the Science Museum’s former Shipping Galleries — it was agreed that the best approach would be to produce a point cloud using LIDAR scanners and high-resolution photography. From this we could produce a high-resolution 3D (.obj) model of Rocket.
On the evening of 16 May 2018, a team of three people arrived from ScanLAB together with over 200kg of equipment, which included a Faro s350 LIDAR scanner, a Phase One digital medium format camera, a Nikon D810, lights, rigs, batteries and computers. Over the next eleven and a half hours — and under the watchful eye of our conservation department — an incredibly detailed scan was undertaken.
This comprised of 22 high-resolution LIDAR scans and over 2,500 high-resolution colour digital photographs (over 220Gb of RAW image data was captured). The resulting model contains a staggering 720,000,000 points.
Rocket was scanned from every angle including from underneath. The scanning and photography were particularly challenging because of the nature of the object. Rocket is complex, black and glossy, all of which present scanning challenges.
Over the next six weeks, ScanLAB processed the captured data into a series of point clouds — data sets that include millions of points each comprising of an x, y and z coordinate, as well as RGB (red, green, blue) colour and intensity values. Three point cloud data sets were produced containing 720 million, 200 million and 50 million points respectively.
Further data processing for two weeks produced beautiful, accurate high-resolution 3D models of Rocket (stored as .obj files). These models were produced at 5 resolutions (recorded in vertices): 750 million, 4 million, 2.5 million, 1 million and 170,000 vertices respectively.
To enable online audiences to easily explore the model without performance or connectivity issues, the smallest 3D model has been published to the Group’s Sketchfab account and then embedded on the Science Museum Group Collection website and on webpages which explore Rocket’s significance.
We are now beginning to explore what else is possible with the point cloud and 3D models. The next steps include building an AR (augmented reality) demonstrator to explore how to give visitors to our museums access to these amazing models.
