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David Fletcher Completes 1000 Cultural Heritage Scans

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Introduction

It has been nearly two years since I wrote my last Sketchfab blog post, Guerrilla Photogrammetry in London. I have now reached the epic milestone of ONE THOUSAND models uploaded to Sketchfab. I feel that I have made big leaps forward in the quality and quantity of objects and places that I have managed to capture and there’s even an interview with me on the BBC News website. I hope that an update might be interesting to all my followers.

The big map

One key thing I have achieved recently is to finally plot all my captures onto a public map. I mentioned in my previous blog that I keep a map of things I intend to capture in the future but when I photograph each place I remove it. Over the summer I spent a few hours each day going through every model I had uploaded to Sketchfab and getting accurate coordinates for their locations. I wanted to keep the source data in a Google spreadsheet so that I could reuse it in different ways. Firstly, I used the Sketchfab API and a custom script to download a list of all my model names and links. I then went through each one and used Google Maps (usually in satellite view for accuracy) to right click and get the latitude and longitude coordinates. I added those to the spreadsheet, too. Now each time I upload a model to Sketchfab I make sure to add its name, link, and coords to the spreadsheet; every few models, I reimport the spreadsheet to a Google My Map, which is publicly viewable. I hope this map is useful to people looking to explore London heritage in an exciting new way.

Exciting new location opportunities

Since my last blog, many amazing people have reached out, asking me to capture specific places or objects. I’m always happy to do my best to help and feel very lucky to have visited so many fascinating and important places.

I apologise to anyone outside London who has contacted me looking for help—my full-time job is looking after my young children and so getting in and out of London on a school day can be very tricky.

In July 2020, I was contacted by Joanna Large from Camberwell. She is part of a community project to protect and make best use of the abandoned Southwark Control Bunker and empty land above it. They have set up a lovely space for local residents to come and meet, relax, and grow produce. The control bunker below was built during the Cold War as a place for local government to retreat in the event of a nuclear attack. There are a few of these bunkers across London in various conditions and the one in Southwark is in a particularly poor state. It is entirely underground and unlit. The floor is flooded to a depth of about six inches apart from the bathrooms, which are full of up to ten inches of thick, stinking gloop. This made photography particularly challenging. I used seven portable LED camping lamps and a diffuse light panel attached to the top of my camera. As I moved around the bunker, I moved the lamps from room to room, always leaving one in the adjoining room(s) or corridor to create light overlap with the last room. If you look closely you can see the little green lamps in the 3D model as well as my rucksack on a shelf in one of the rooms. The smell in the bunker was pretty bad so I had to work quickly—but it still took a full morning to get every room photographed. I’m really proud of the result, though, because these bunkers are fast deteriorating and I’m not aware of there being another 3D capture of one online. I would love to do more if anyone can give or get me permission to visit a control bunker, air raid shelter, or Royal Observer Corps monitoring post.

Southwark Control Bunker. A rare view into a Cold War nuclear bunker.

At the end of 2020, Colin Fenn, a trustee of Kensal Green Cemetery, contacted me after seeing my capture of the crypt at St Pancras New Church. He was very keen to get a capture of the crypt under the Dissenters’ Chapel at Kensal Green and I was more than happy to visit. Colin is particularly interested in the care and workings of crypts like these and is conducting research of several around London. Having a good 3D model of the crypt really helps him to understand both its condition and layout. The crypt is partially lit but some corners are very dark, so I again used my camping lamps and diffuse panel to shoot the whole space. It made for a really great scan because every surface is textured and detailed, allowing Reality Capture to easily align the photos and produce a really accurate final model. I also managed to capture the chapel above the crypt and the exterior of the building on a separate day. Having both interior and exterior scans allowed me to piece together all the sections and reveal the relationship between visible and hidden parts of the building. Colin and I hope to return to the cemetery in the near future to capture further incredible crypts and catacombs.

Kensal Green Dissenters’ Chapel and Crypt. I also chose to upload higher resolution models, which are linked from this model, of just the crypt to Sketchfab.

In early 2021, I read via Twitter that the famous and very old sailing shop, Arthur Beale on Shaftesbury Avenue, was to close. Shortly after, Louise Calf reached out to me and kindly offered to put me in touch with Grit Eckert who works with the management and has a keen interest in preserving the records and heritage that they have amassed over the centuries. I met up with Grit one Saturday morning in May and spent a really happy few hours photographing as much of the store as I could. It was really interesting listening to Grit explain the history of the business and seeing some of their fascinating records. I photographed the main shop floor, the basement store rooms, attic, and upper floor store rooms, allowing me to produce a complete collection of models on Sketchfab. This set of captures, I hope, will be a surviving record of how the shop looked just before closing down and will allow others to virtually visit and experience an important piece of history. I feel really lucky to have been allowed to capture Arthur Beale at a critical moment, this being a unique overlap between the required technology existing and the shop still being open.

The shop and basement stores of Arthur Beale, now closed.

In my last blog post I described my passion for capturing the fast-changing landscape of the Thames foreshore and I continue to do this as much as the tide will allow. At the beginning of 2020, I was contacted by Alan Murphy who is a full Thames mudlark. Alan lives in Rotherhithe and spends as much time as possible out on the foreshore looking for finds as well as caring for larger historical objects that lie there. In the paste, objects such as ships’ timbers have gone missing from the foreshore, either carried away on the tide or worse, stolen. Alan is on a mission to secure and look after these timbers for future generations. He invited me to Rotherhithe to see the timbers and 3D capture as many of them as possible, which I was delighted to do. I managed to capture about a dozen timbers and even had time to photograph Alan himself—my first scan of an actual person. I recently acquired a 3D printer and, after printing a miniature Alan, was able to send him a model of himself. Alan also put me in touch with Elliot Wragg from the Thames Discovery Programme to help capture ships’ timbers located in Sands Films Studios in Rotherhithe. While Elliott and his team of volunteers recorded the ships’s ‘knees’ used in the fabric of the building using pen and paper, I went round photographing them to produce 3D models. Ultimately, I produced 24 different models that I hope will be of use to future researchers; they can all be seen in this collection on Sketchfab.

The brilliant and patient Alan Murphy, full mudlark and my one and only scan of a person.

Selling on Sketchfab

Over the past few years a big surprise has been an increase in my Sketchfab sales via the Sketchfab Store. I make about five percent of my uploads pay-to-download in the hope that this will partly fund purchasing future equipment I need for photogrammetry. When deciding whether a model I upload is free to download, not downloadable, or paid download I use the following methodology. Firstly, it is worth noting why I capture heritage locations in general. I passionately believe in the recording (to the best of my abilities and technology) and public sharing of heritage, particularly in London, a city I live in and love. I want people to visit places they may not be able to reach and future generations to see what the world looked like in our time. Some locations I have captured have already changed or been lost entirely and I hope that by capturing as much as possible with technology that is as advanced as possible, I am creating a valuable record akin to the early days of photography and film.

This philosophy leads me to make as much as possible of what I upload freely downloadable so people can reuse the models in innovative ways. Some models of historic locations are not downloadable at the request of the owners or custodians who allowed me to capture them. I always explain the merits and possible outcomes of downloadable or not and let them decide.

When it comes to which models to sell, I tend to do this for objects or locations that exist in the public realm and that I have captured in particularly high quality. Models that I put up for sale also tend to be of more modern locations. For example, I have made most of my skatepark and urban graffiti locations paid downloads as these take a long time to capture and people really enjoy using them in their own projects.

Whites Grounds Skatepark near London Bridge.

Lockdown

Late 2020 into early 2021 was obviously the year of the COVID lockdowns. During this period I found myself with much time to ponder what I captured and why; it also gave me a chance to make new contacts for future projects. The main disadvantage from a photogrammetry perspective was that I could not go out and photograph heritage. However, as soon as the lockdowns lifted and I was able to continue my longer walks around London, a quieter city emerged where I was free to photograph usually busy locations without disturbance. For example, small parks such as the ruins of St Dunstan in the East would usually have been full of city workers but were now empty. With people working from home and missing London and its sights, my photogrammetry models gave many people a reminder of the places they love but could not visit.

London itself is starting to return to its normal busy self, albeit without the usual huge numbers of tourists. I continue to be out as much as my free time will allow, on longer and longer walks, looking for new places to capture.

St Dunstan in the East, a ruined church and now city park. Quieter in a post-lockdown world.

Cameras

The biggest change in quality in my captures over the last year has been due to a change in camera. I recently upgraded from a Sony a6000 to a full frame Sony a7R III with a Sony 16-35mm f4 lens. The main difference with this new camera is the resolution—photos are now 42.4 megapixels rather than the a6000’s 24.4mp. This improved resolution has the advantage of allowing me to capture more detailed models and textures. The disadvantage, however, is that processing is now slower as Reality Capture has to work with larger photos. I am also using up storage space on my NAS drive faster than before. I take all my photos in RAW and JPG and always keep both. With the new camera, I have also had to switch to processing JPG files rather than RAW due to Reality Capture not wanting to import the ARW files that the a7R III saves. It worked for the ARWs from the a6000. I’ve contacted Capturing Reality about this and I hope they fix this as I really prefer importing the RAW files into RC and letting it figure out how best to work with them. I did try manually batch converting my RAW photos to JPG using Lightroom and then using those images instead, but in addition to that taking a very long time, I also didn’t notice any improvements over the camera-generated JPGs in the final model.

I often still take my a6000 with me, too, because I have a 200mm zoom for it which can come in useful. When I get a zoom lens for the a7R III, I’ll leave the a6000 at home.

Software

I now nearly entirely use Reality Capture for processing my models. When Capturing Reality was acquired by Epic Games, Steam subscribers were upgraded to a full license, which means I can process any number of photos without limitation. This has been a huge advantage and I thank them profoundly for this. I hope that Capturing Reality sees the value in my use of their software for the recording and free publishing of heritage for public good.

Large location photography

I’m often asked how I shoot large locations like church interiors. I try to work methodically so as not to miss any areas or angles, although that can still happen and I occasionally return to a location to fill in holes. If the location is made of rooms I work by photographing around the room with my back to the wall and then walking up and down looking at the ceiling and floor. I then focus on individual objects in the room, taking loops of photos around them. If the location is large such as a church I will walk up and down taking photos every step or so, forwards, 45 degrees up and 45 degrees down. I then walk sideways taking photos along walls, aisles, pillars, etc. This can take a few passes depending on how tall the space is and may require extra passes looking slightly up and down to get the joins between walls and floors/ceilings. I then stand in key positions taking photos in 360 degree circles while rotating on the spot. As many of these rotational sets, the better—getting into hard-to-reach spots helps, too. If I can get high up and photograph downwards, I will. In churches this might include balconies, pulpits, and triforiums, for example. All my photography (apart from on an extended pole) is handheld so I try to keep an eye on each photo taken on the camera screen and immediately delete and reshoot any that are blurry.

Drone photography and tall structures

One question I’m asked nearly more than any other is how do I capture the tops of buildings and large structures. Many people assume I use a drone. Some of my early captures were captured using a drone (DJI Phantom 2) in a time when they were far less common, and unregulated. I discarded my drone many years ago. Now drone photography rightly requires a license and has become very difficult to do in London. Flying one anywhere in London requires permission from several places, such as airports and land owners and, unless being done as a full-time occupation, is not practical. I therefore use other methods to achieve the best result I can for the higher-up parts of scans. My first approach is to get as far away from the subject as possible and zoom in. In parks this can be easy, just trying to avoid trees that might obscure things. In built up locations, this involves walking away down nearby streets with lines of sight back to the subject while continually taking photos. Sometimes parallel streets offer views over lower structures to the top of the subject and I’ll make use of those, too. This might require a bit of manual aligning in Reality Capture later if it can’t find the relationship itself. If there are public nearby structures or buildings that I can climb, I will do that and take elevated photos. Rooftop bars or nearby hills can sometimes help.

I also use a 67 inch monopod to raise the height of my camera and get elevated shots. I make sure to get several shots with the pole half raised so that the fully raised photos have the best chance of aligning with the handheld ones. Very occasionally I’ve also used a 2.7 meter selfie stick with a GoPro on the end for even higher shots. I’m also considering buying a 5 or 10 metre inspection pole but these are expensive and cumbersome to carry.

View of Star & Still Pub in Reality Capture showing camera positions to capture top.

One-thousandth model

In summer of 2021, Chris Romer-Lee contacted me to ask if I would be able to capture the architectural artwork ‘Writ in Water’ at Runnymede. This reflective space was built to celebrate Magna Carta and the founding principles of democracy; I wanted to produce a really high quality model of it. I took just over 3000 handheld photos of it, inside and out, including several from a nearby hill in the hope of getting some of the top captured. The final model took some cleanup and interpretation, such as filling in missing parts of the roof, to get looking right. It was also really important that I recreate the reflective water so that the key inscription could be read. This was done using the tried and tested video game technique of duplicating and flipping the inscription mesh below the water line.

Writ in Water, an architectural artwork by Mark Wallinger at Runnymede, Surrey.

The future

There are plenty of locations around London I would love to capture and I continue to update my map of places to visit whenever I hear of something new.

For example, there is an enigmatic lost world, just south of Stratford called Channelsea Island. Originally it was the site of a 12th century mill and then later a chemical works; what remains now is an (almost) unreachable overgrown set of slowly deteriorating ruined buildings. The island is currently owned by a nearby mosque and only reachable at certain tides and by boat. I’d love to capture this fascinating place, preferably in winter when the vegetation is less dense.

If any custodians or trustees of interesting places would like me to visit I am always happy to come along for a chat and see what I can do. Further I would love for my photos to go into a museum archive for posterity.

About the author

David Fletcher

David Fletcher is a computer artist at Sony Interactive Entertainment as well as a stay-at-home dad with a passion for heritage and archaeology. In his free time, he scans heritage sites around London where he lives.



8 Comments

  • https://sketchfab.com/matousekfoto says:

    Congrats, amazing collection!

    On importing raws: it works with Nikon NEFs for example, however, RC only uses the small embedded jpg files inside the raws… so it doesn’t make much sense to do that… the obvious advantage of raw is that you can process it in something like Lightroom and get even better control and more details from the pictures…

  • Vasilis Haroupas says:

    Congratulations!
    You’re doing an amazing job and your consistency is truly inspiring.

  • Diêgo says:

    Hello David, hello everyone! I live in Brazil, can I use these 3D models for free without giving credit to the author? I think these models are in the public domain, am I right?

  • Matthew says:

    This is a beautiful inspiring collection! Thank you for sharing it. I love London and already knew I have not spent enough time there, now I have even more reasons to visit.

  • unfa says:

    I think Sketchfab should implement a first-person style walking controller with collision. Navigating these scans would be much more immersive that way 🙂

  • David Seeliger says:

    @David Fletcher
    Congratulations on the 1000! I keep looking at your scans for quite a while, impressive every time!

    @unfa
    You have the possiblity to walk in some of the models in VR.

  • Mark says:

    I agree with unfa – this would make a great first-person exploration game. Maybe add some easter eggs about production technique for the more challenging sites. Where can I sign up?

  • Earl Laamanen says:

    Great work. Your scans are a primary reason I stuck around Sketchfab week to week, and now I’m pretty interested in doing this myself and contributing some scans from my part of the world.

    It would be nice if Sketchfab allowed you to record a world position for a model origin — these are all real places so why not georeference them!

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