Category Archives: 3D Scanning

Supported by Share Academy, the Philatelic and Digital teams will be partnering with UCL on a year-long project to document and scan objects from the Philatelic collection, such as dies and rollers. This blog will document the progress and provide important updates.

Experiments in Photogrammetry

Recently we experimented with producing a set of 3D models of items from the collection using a process called photogrammetry. Rose Attu, a Digital Humanities MA Student from UCL, who’s currently on placement at the BPMA, talks us through the process.

To create a 3D model a series of overlapping photographs of a single object are taken from different positions, and then a piece of software is used to triangulate the coordinates of each image and align them, reconstructing the whole object in 3D. With each shot, the digital camera also records metadata including the focal distance between the lens and the object; this enables the software to recreate the position the camera was in when each photo was taken.

Curator Emma Harper holding the stamp snake

Curator Emma Harper holding the stamp snake

The objects we chose were the prosthetic Postman’s Hand and the Stamp Snake. An object covered in a repeating pattern, or one without any distinguishing features at all, will affect the software’s ability to rebuild the depth of an object. Both these objects have plenty of distinctive features, so the software could detect the details from photo to photo and build accurate models without distortions.

Postman's prosthetic hand being photographed

Postman’s prosthetic hand being photographed

Our first object was the Postman’s Hand. Once it was in frame and in focus, and evenly lit to avoid shadows, we could begin the capture process. To capture our objects from multiple angles we used a turntable to rotate them through 360°. The turntable was also covered in a distinctive image, which gave the software more common points to identify. The turntable was edited out at a later stage, so that our final models were just of the hand and the stamp snake.

Stamp snake being photographed

Stamp snake being photographed

On average it took 30 photos to complete one rotation, after which the camera was raised for a second sequence capturing the object from a higher angle. For more consistent results we kept the camera settings the same until a rotation was complete, and used a tripod and remote shutter release to keep the camera static. We output the raw image data as a set of TIFFs and corrected the white balance, and then our images were ready to be transformed.

Based on the estimated camera positions and the details in the images, the software built a point cloud, which is essentially a 3D model made up of dots. It then added a more detailed polygonal mesh layer representing the object surface. The final step was to add the textures; because we photographed our objects in high resolution, even the tiniest details were visible on the final models.

Snapshot of the 3D model of the stamp snake. Manipulate the model on Sketchfab.

Snapshot of the 3D model of the stamp snake. Manipulate the model on Sketchfab!

We were surprised with how little effort and technology it took, and the results were fantastic!  For our set-up we used:

  • Lazy Susan turntable with a nonrepeating pattern on it
  • Digital SLR camera and tripod
  • Light box or tent
  • Studio lights or some source to help get rid of shadows
  • Photogrammetry software – we used Agisoft which was great and you get a 30 day free trial

Have a go yourself– we would love to see your models!

– Rose Attu

Capturing Mail Rail in 3D: The Next Steps

Imagine a place frozen in time, left exactly as it was the day that everyone left it. That is what it’s like in Mail Rail today. After it was mothballed in 2003, everything was left as it was that day, down to the newspapers, rota and personal belongings. This time capsule effect is part of what makes Mail Rail unique and exciting; however when we start construction later this year to convert it into a ride and visitor attraction we’ll have to make a few changes to ensure it’s safe and accessible for visitors. We are keen that the space remains as true to how it is now as possible, but these changes mean that the little things could be lost. We thought long and hard about how we could preserve Mail Rail exactly as it is today. The solution we came up with was 3D scanning.

Just before Christmas ScanLAB Projects, a 3D scanning and visualisation company based in East London, spent a week down in Mail Rail and captured the Mount Pleasant depot, loop and platforms in 3D. In total they completed over 223 terrestrial laser scans with incredible and accurate results.

View of the Mount Pleasant platforms

View of the Mount Pleasant platforms

The scans that ScanLAB have created show all the minute detail of the spaces, preserving Mail Rail as it is now for us all to explore in years to come, including parts of Mail Rail that visitors to the site won’t be able to see, such as the train graveyard.

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Fly-through of the train graveyard

 

Of course the results have got our creative gears spinning. Increasingly visitors are expecting an increased level of digital interactivity from a visitor to a museum, allowing them to interact with exhibits and collections through devices such as smart phones and tablets, before, during and after their visit – but how can we use these scans to enhance the visitor experience, both physically and remotely?

The guys at ScanLAB gave us a demo of just this; using an Oculus Rift headset we explored the train graveyard and the depot. BPMA staff delighted in walking around, reaching out to touch trains and walls, and even ‘sitting’ in one of the trains!

Looking around the Mount Pleasant Depot through Oculus Rift headset

Other possibilities include augmented reality apps for smart devices, projections or 3D printed installations –the options are endless– so what would you do with them?

Exploring 3D technologies at the BPMA

The last 12 months have been exciting for the Digital team here at the BPMA. Our Share Academy/London Museums Group funded project, From Vault to View, which partnered us with Mona Hess from UCL’s Civil, Environmental and Geomatic Engineering Department, has given us both a lot to do and to think about. The project has now come to an end, but it has increased the knowledge we now have of 3D technologies, and encouraged us to do much more.

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George V Die for striking leads. 1½d postage British Empire Exhibition, 1925

The aim of the project was to test different methods of capturing objects in 3D. Working with our little-viewed objects, Mona tried a variety of techniques to see what would produce good 3D models and what wouldn’t. The objects chosen posed real challenges: many were made of bright metals, which makes them difficult to capture using laser scanning or photogrammetry techniques; some were complex shapes, such as a flintlock pistol; while others had such a lack of detail making them difficult to measure and recreate as 3D computer models.

So what did we get out of it? Before the project we knew very little about how 3D

imaging worked. We felt the buzz around these technologies, such as 3D printing, but had little idea of how these things were created or how they might be used. All we really knew was that we had a rich treasure of 3D objects that no-one could really access physically in a satisfactory way.

By the end of the project, the BPMA had purchased photogrammetry software which has enabled us to try 3D imaging for ourselves – and the results are extremely promising. These techniques can be learnt by our staff and employed to create 3D models of items in the museum collection for exploration by the public.

This new-found knowledge, though still fairly elementary, has given us confidence to explore other uses for 3D imaging. In December 3D experts, ScanLab Projects, spent a week scanning the work depot, platforms and tunnels of Mail Rail which we will be opening to the public in 2016 as part of our plans for The Postal Museum. The results are truly astounding and we hope to show them in the near future.

Scanner capturing Mount Pleasant platform

Scanner capturing Mount Pleasant platform

Beyond all this, the project has given us an opportunity to revisit the objects and see them afresh. Although we weren’t able to obtain good 3D models of objects such as the large printing plates and the rollers, we did get excellent images of a number of dies using a technique known as Reflectance Transformation Imaging [RTI]. We also obtained an excellent laser-scanned 3D model of the Machin cast of Queen Elizabeth II – a truly unique and iconic object. The fruits of these experiments will eventually be made available via our website and online catalogue as we integrate the technology.

Plaster head of HM the Queen made by Arnold Machin for new definitive issue of stamps, third version (POST 118/5373)

Plaster head of HM the Queen made by Arnold Machin for new definitive issue of stamps, third version (POST 118/5373)

-Martin Devereux, Head of Digital

Capturing Mail Rail: 3D survey of the depot, loop and platforms

Last week was an exciting one for the Digital team here at BPMA! For the past five days, Rachel and I have been accompanying ScanLAB Projects Ltd. while they undertake a 3D survey of Mail Rail.

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Scanner capturing the west platform.

 

ScanLAB have been targeting the areas of the network that are to be the focus of our Mail Rail  visitor attraction – that is the work depot at Mount Pleasant, the platforms beneath Mount Pleasant and the tunnel loop from the depot to the platforms – just about 1km of tunnels.

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Will from Scanlab discusses the technology with guests from FARO, New Scientist and Harry (BPMA Communications Manager).

 

The 3D scanning of Mail Rail is important in that it captures the industrial heritage of an unexplored and little-known feature of central London. The survey records the details and the features of Mail Rail as a working space, with all the flotsam and jetsam left behind when the service was suspended. From tools and equipment to newspapers and calendars from over a decade ago, Mail Rail is a time capsule just waiting to be explored. These features will inevitably be tidied up when we open it to the public so it is crucial to capture that detail for posterity.

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Thomas and Will from Scanlab sharing the raw data.

 

The survey will allow users to see these features in three dimensions – bringing the platforms to life in ways not possible even when the train ride is running. The survey can be shown via the web and used in the exhibitions we create at the Postal Museum and Mail Rail attraction to offer a truly explorative experience of Mail Rail in a way that the train ride cannot. Imagine navigating the tunnels and platforms for yourself?

Scanner on the platform.

Scanner on the platform.

Using the latest scanning technology from FARO, and using the surveying and imaging expertise of ScanLAB, we will be obtaining as faithful a representation of the site as we possibly can. From the work depot to the platforms and the tunnels in the loop around Mount Pleasant, we will be recording a truly significant piece of Britain’s industrial history.

-Martin Devereux, Head of Digital

3D Scanning moves into its final phase

Over the last fortnight we have been undertaking the latest stages of scanning of our 3D philatelic objects as part of our Share Academy funded project – from vault to view.

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Scanning the flintlock pistol.

We took a number of dies, including the Old Original die of the Penny Black, and the Silver Wyon Medal, over to UCL to be photographed in a PTM dome. The dome is opaque and is fitted with 84 flash lights arranged in rings around the hemisphere. Each flash is activated one at a time and a photograph taken. Once all 84 flashes have been triggered the resulting 84 photographs are processed together into one image so that all the lighting conditions can be observed via a special viewing computer program. The observer can manipulate the lighting condition to reveal hidden features – the engraving, the scratches on a die, etc

The activity described above is part of a series of techniques for a process known as Reflective Transformation Imaging (RTI). You can find out more here – http://culturalheritageimaging.org/Technologies/RTI/

ptm_dome

Scanning at UCL

The results of this test are still being processed, but the images we’ve seen so far are impressive and we’re very excited by them.

Last week UCL’s 3D specialist, Mona Hess, visited the BPMA bringing a portable 3D laser scanner with her. This was to be the last set of trials with laser scanning and we wanted to try the same set of objects which were digitised by the PTM dome. This time around, the results were more mixed as the laser had difficulty with the shiny surfaces of the dies and medal. We also tried scanning the flintlock pistol we had scanned previously with the large laser scanner at UCL and the results were slightly better. The scanner rendered the wooden parts of the handle and stock, but struggled to render the metallic parts, such as the barrel and the firing mechanism.

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Latest tests at the BPMA

The preliminary findings of the tests show that the PTM dome renders the most useful images of metallic objects from the stamp printing process. We have one day of scanning left to complete in this fascinating project and we will then make the results of the whole project publicly available.

After a break following the first trials of our 3D scanning project

After a break following the first trials of our 3D scanning project, work continued last week when Martin Devereux, Head of Digital, and Stuart, Philatelic, took three objects to UCL to be scanned by Mona Hess, our 3D specialist. 

These were no ordinary objects, however. Stuart, our philatelic archivist and I took a flintlock pistol used to guard mail coaches, a handstamp used to cancel mail carried by the first airmail trial in 1911, and an iconic plaster cast of Her Majesty the Queen, sculpted by Arnold Machin. The Machin cast is recognised around the world as it has appeared on UK stamps since 1967.

Handstamp getting scanned by the

Handstamp being scanned by the Arius 3D colour scanner.

Each of these items poses a serious challenge to current 3D digitisation techniques. Glossy surfaces and deep features mean that lasers do not work as effectively as with less shiny and less detailed subjects.

Mona spent over 3 hours scanning the plaster cast with the Arius 3D colour scanner, while Stuart and I, along with MSc student, Sarah Sifontes Duran, captured the geometry of the handstamp and flintlock pistol, using an infra-red scanner – a technique that Mona is pioneering. The aim of this work is to produce a set of techniques which can be combined quickly and at low-cost to produce accurate and detailed representations of objects in three dimensions.

Stuart carefully transporting the Machin cast.

Stuart carefully transporting the Machin cast.

Output of the Machin 3D scan.

Output of the Machin 3D scan.

Digitising the plaster cast of Her Majesty was the climax of the day and a highpoint for Mona. She has scanned many memorable objects over the years and the Machin cast is certainly a significant addition to her list.

Flintlock pistol being scanned.

Flintlock pistol being scanned.

Machin cast close-up.

Machin close-up.

Once the cast had been scanned, the remainder of the day saw the scanning of the flintlock pistol and handstamp using the Arius colour scanner.

Mona is working to refine the results of the trials and further work will be undertaken over the summer as the project moves forward.

-Martin Devereux, Head of Digital

From Vault to View: Scanning trials

It’s been an exciting month for those involved in our 3D digitisation project, as it moved into the trial stages. A while back we shared what objects we selected for the scanning. A couple of weeks ago, Mona Hess, the project’s 3D digitisation specialist, visited the BPMA to undertake trials of low-cost scanning and photogrammatery techniques. 

In conjunction with our Conservator, Krystyna Koscia, Mona tested the application of a cyclododecane spray – a substance which, when applied to objects, makes them easier to digitise with a laser–scanner.

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Cyclododecane spray applied to test objects.This substances evaporates shortly after application and makes the object easier to scan with a laser.

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Mona applies the Cyclododecane spray to test objects as Krysia looks on.

The main event of the day was the photographing of a large printing plate against a target background, from which photogrammetric measurement will be taken to create a 3D map of the plate. You can find out more about photogrammetry and other techniques we will be using in this post. The plate was also scanned using a low-cost laser scanner, to obtain a rough geometry of the plate itself. Other objects were also photographed and scanned, including a die, an embossing die, a slogan die and a roller.

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Martin examines the plate.

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Mona standing on a stool for photogrammetry imaging.

You can check out the preliminary 3D model of the plate online now, and manipulate the model. We promise that the final results will be more detailed!

Trials continue in May, when Mona will be using the laser-scanner at UCL to scan other key objects from the collection.

-Martin Devereux, Head of Digital