Categories
3D Penzance

Point Cloud Penzance – the town in 3D

Using 3D data (LiDAR) collected by the Environment Agency through the Government Open Data initiative I have created an interactive 3D model of the town centre of Penzance, Cornwall.

It’s a very detailed model, with a measurement point every 50cm or so across the entire town. There are 12.9 million vertices (points) in this model.

You may need a reasonably modern computer for the model to work correctly, but give it a try. Use your left mouse button to rotate the model, right-hand button to pan, and the scroll wheel (or equivalent gesture) to zoom.

View this model directly on Sketchfab, where you can try full-screen mode.

If you get too close to buildings you may notice that you can see the ‘points’ that the model is made from. In the future technology will allow agencies to collect much more accurate and dense data, and faster computers will allow us to view more detailed models. Until then – enjoy!

LiDAR data is extremely useful to archaeologists to identify features in the landscape. This is my primary use of such data. In the future data like this will be useful for understanding how our towns have changed. This model is presented here for a bit of fun, and to demonstrate the many uses that this kind of data can have.

Penzance LiDAR
Penzance LiDAR with Ambient Occlusion to show streets and features more clearly.
Categories
Broadband News

My Fibre to the Premises (FTTP) Installation – Part 1

When I first moved to Penzance in January 2012, BT Openreach’s fibre rollout was already well underway in Cornwall. The Penzance exchange was due to be enabled that May, and in my mind I thought that a few months would be well worth the wait. Well, it turned out to be more than a few months!

In February 2012 I registered my number with Superfast Cornwall to be informed when fibre of one kind or another (Fibre to the Cabinet – FTTC, or Fibre to the Premises – FTTP) would be enabled on my line. By the end of August this year (2013) I decided to check my number again as I hadn’t heard anything and there seemed to be a fair number of BT Openreach vans and roadworks in the area. The line checker came back with a friendly message saying that my property was eligible for FTTP – one of the few that would receive ultra-fast broadband.

After carefully reinstating my jaw from its newly found location on the desk in front of me, I looked up BT’s packages to find out how much it would cost. We currently pay £25/month (plus line rental) for a standard unmetered ADSL connection which on a good day peaks at 11.25Mbs down / 0.7Mbs up. BT offered a 160Mbs/20Mbs FTTP connection for £35 with free installation. That’s a lot of extra speed for not a huge sum of money – and when you work from home and are reliant on broadband any increase in speed, especially upload speed, can make a huge difference.

Naturally, I signed up. (Order date: 30 August 2013)

Installation of FTTP

I was given two dates for the installation. The first visit would be for the fibre to be run to our house on 20th September, then an engineer install the remainder of the fibre into the house and to connect up the new fibre modem on 1st October. I’d waited this long, so thought that those dates were reasonable.

Then a few days later I received a call from BT Openreach saying that they have had to delay the installation, and I was given new dates for the visits. The external work would be completed on 4th October, and the engineer visit would be on the 15th. A bit of calendar re-shuffling, but still OK. A tiny part of me wondered if it would even be possible, and the dates would march off into the distant future.

I was wrong.

This morning (20th September) at about 9am, there was a knock on the door. “Hello, I’m here to install your fibre broadband”.

The “external” appointment, I was told, meant that it was optional for me to be at home. But be warned – that’s not always true. In the case of our house, we have a locked rear courtyard which we needed to let the Openreach engineer into. It can also be helpful if you are in to help the installer know where you would like the fibre to enter your property. They also tend to respond favourably to offers of tea.

What happens during the “external” fibre installation appointment?

An armoured cable needs to be run from either the pole (in my case) or underground to your property, terminating in a small box called a Consumer Splice Point (CSP) over or near the point where the fibre enters a hole in your wall/window casement.

Here’s mine, taken during installation:

BT Openreach Customer Splice Point (CSP)
BT Openreach Customer Splice Point (CSP) during installation

Bear in mind that the steel-reinforced outer cable cannot be bent along a right angle – there must be smooth curves for it to turn a corner, and so this may affect where the cable is installed.

Once the armoured cable and CSP are in place, then the fibre itself is “fusion spliced” at the fibre terminator on the pole/duct/cabinet (delete as appropriate) and “blown” with compressed air down the cable. As I typed this, that’s just what they did:

CSP with fibre blown through the cable
CSP with fibre blown through the cable

And then a quick photo of the end of the fibre optic:

End of the fibre optic
End of the fibre optic

And finally, the completed CSP, ready for the second BT Openreach visit:

FTTP Consumer Splice Point
FTTP Consumer Splice Point

The BT Openreach engineers who undertook the installation were great – professional and courteous. Details of the next stage in a few weeks time.  [Update] Find out about stage two of my FTTP installation.

Categories
3D Archaeology News

A Medieval Discovery at Gulval Church, Cornwall

Gulval Cross-BaseJust to the left of the south porch of Gulval Church, near Penzance in Cornwall, lies a large block of granite. I first came across it on a visit to the churchyard in 2012. However, it really piqued my interest a couple of months ago after reading a short report in Newsletter 132 of the Cornwall Archaeological Society. The article, entitled ‘An unusual stone at Gulval Church‘, by Professor Mick Aston, Teresa Hall, Professor Rosemary Cramp, Ann Preston-Jones and Andrew Langdon, highlighted that the block was a medieval cross-base, and was decorated on all four sides. Aside from the south, pictured here, the images on the other sides were very difficult to see at all. Ann and Andrew visited the stone at night “armed with car batteries, a mirror, two spotlights, a tripod, head torches, and a camera” to capture raking light photos of the decorations to see if controlled shadows could be used to interpret the decorations.

The results were good, producing a set of shadowy atmospheric photos of each side. Professor Cramp began to interpret the scenes from these photos but noted that, while useful, the photos only provided a single fixed view, and she had not seen the cross-base with her own eyes. It was thus difficult to say for sure what was depicted on this rough stone.

It was shortly after receiving the newsletter that I also heard the sad news of Mick Aston’s death. Doubtless that Mick would have had a continued interest in the cross-base, and given that I only live a few miles from the church I became determined to use the tools available to me to record the cross-base and see if I could help with the interpretation.

On 8 June 2013 I visited Gulval Church and recorded in high resolution 3D each side of the cross-base using a photogrammetric approach. Taking a series of over a hundred overlapping 18 megapixel scale photos at a fixed focal length, I covered the whole block.  It was quite a tricky subject to tackle, as there is very limited clearance between the cross-base and two of the church walls.

Over the next few weeks, I began to process the images into 3D point clouds, and from there to solid 3D meshes. Afterwards, I subjected each side to a series of techniques which I have used to analyse prehistoric rock art and inscriptions in the past. The results were fantastic.

What is depicted on the cross-base?

Thanks to this analysis, I believe that we now know what is shown on the cross-base at Gulval. The existing interpretations, as laid out in the CAS Newsletter, didn’t match up with what I have found. The computer-generated images, shown below (and may others that I have created using false colour representations of depth), have been able to provide a slightly clearer representation of the granite carvings, and, I believe, help perceive them in a different way. I can now see many of the details in the original photos now that I know what I am looking for.

Rather than sit on this discovery for ages until everything is just right, I have decided to post my initial findings here. It does not represent a full description of the findings and condition of the cross-base and its imagery, and it builds upon the work already done.

Firstly, I must thank my friend, Nick Ford, for putting me onto the iconography – I believe that he spotted what was depicted in the first image I showed to him straight away, and knew what the others would reveal. It led to an exciting evening searching for comparative images, and further enhancing them. And without the original report in CAS Newsletter 132 (now online) I wouldn’t have got this point at all.

The cross-base depicts the four Evangelists, Matthew, Mark, Luke and John, as the four living creatures described in Ezekiel 10:14 and Rev 4:6-7

Revelation 4:6-7

New International Version (NIV)

6 Also in front of the throne there was what looked like a sea of glass, clear as crystal.

In the center, around the throne, were four living creatures, and they were covered with eyes, in front and in back. 7 The first living creature was like a lion, the second was like an ox, the third had a face like a man, the fourth was like a flying eagle.

The Gulval Four Evangelists

The south side of the stone depicts St Matthew. He is symbolised as a winged man or an angel, and depicted here with a halo, holding a book (Gospels or Book of Life?) with “MT” inscribed on it. The lower part is damaged. This image shows the details picked out using an ambient occlusion filter.

On the west, facing outwards, is St Mark. He is shown kneeling, with haloed lion head. His book, held in his left hand, has “M” on it. It is possible that he is giving the sign of benediction with his right. The folds of his robes are nicely visible.

On the north, facing the church proper, is Luke, depicted here seated with haloed calf head . His book, held in a rather large left hand, has “LS” on it (Lucas). Luke is mainly depicted as an ox, but it isn’t unknown for him to be shown as a calf.

On the east, facing the porch wall, perhaps the most badly eroded of them all, is St John, depicted as the eagle. His robes, especially the folds around his legs, are clearly visible.  It is difficult to discern the presence of any halo. He is holding a book in his right hand, with what looks to be an “H” on it (not easily visible in this image – only range-colouring a very small area shows this). It would be very neat if it said “IH” – Iohan, but archaeology isn’t always a neat discipline. Further work needs to be done here.

We must remember that the stone block onto which these images are carved is a course Lands End granite. Some of the quartz crystals are several centimeters long – fine detail just isn’t possible – and granite can crumble when exposed to the elements.

A Tetramorphic Cross-Base?

So there we have it. Starting on the south side of the stone, if you run the sequence clockwise (South, West, North, East), runs the familiar sequence of Matthew, Mark, Luke and John. Matthew, the best preserved of all, was positioned facing outwards, and the shield-like shape of the carving has, according to some, become thought to be a coat of arms. Now that we know what is really shown here, perhaps we can even call it a tetramorphic cross base, bringing together the symbols of the Four Evangelists together into a single object. One thing is for certain, however, and that is a lot more work needs to be done on the Gulval cross-base, in terms of research, verification, and recording techniques. Reflectance Transformation Imaging (RTI) will certainly be the next approach for further enhancing the panels. Comparative examples need to be sought.

This could have a big impact upon our understanding of Gulval, and indeed have ramifications on how we understand the history of this part of Cornwall in the early Middle Ages.

The authors of the original article in the CAS Newsletter have had copies of the images and my findings in advance of this blog post. Luckily, when I sent my findings to Ann Preston-Jones, she was pleased, as she felt that these were the Evangelists, but lacked firm evidence to back it up. I trust that my arguments, and the images above, will help to win around any doubters.

I have been asked to add the finished images of the Evangelists to the forthcoming Corpus of Early Cornish Sculpture, to which I am honoured to be able to make a contribution. The vicar of Gulval Church is adding the images to his parish newsletter. Who knows, even a sermon may come of it!

Further images and information will be added to subsequent blog posts, and linked from here, so do bookmark this page and check back from time to time.

And now for the plug!

As an independent archaeologist, I am of course pleased to offer my professional services. Please contact me with any enquiries.

Below is a series of images of St John (Eagle) from the east side of the cross-base. The 3D data has been filtered in a number of ways to extract the detail of the carving.

East elevation of a medieval cross base at Gulval, Penzance, depicting St John the Evangelist as an eagle (see Rev 4:6-7 & Ezekiel 10:14). Captured using photogrammetric methods and processed using different filters to interpret the carving.

Categories
Penzance

Open Shed – a new hackspace in Penzance

Open Shed

[Update May 2014] Sadly Open Shed closed in May 2014 due to the inability to grow membership enough to meet costs.  

For the last six weeks I have been doing something a little bit different. From a friend, I heard that a small group of people were setting up a hackspace to provide a place for people interested in and working with technology to get together to work on projects. It would include a hot-desking (coworking) area for people working at home to escape and work in a more sociable way, whilst sharing skills and knowledge, a room for events and courses. There would be an electronics lab, a workshop, and a small café, and the chance to meet with like minds. I was excited at the prospect.

The hackspace was to be called Open Shed, and I signed up to the email list as soon as I could. A scout through the list archives revealed the prospective premises, the ground floor of Champions Yard in central Penzance, so I popped round the next day to have a peer through the window. The space looked huge, but two thirds full of junk and old machines from its former days as an amusement arcade, and one third full of the remains of a video library. But what a space. Loads of potential. Whilst looking through the murky glass, David, a member of the core group setting up Open Shed, cycled up behind me and asked me if I would like to look around – he was just about to get the keys. Well, the premises were spacious, but divided up with stud walls and absolutely full of junk. Potential and challenge in equal measure! I asked to help out there and then – this had to be made a reality.

Fast forward six weeks, and Open Shed opened for its members. As a social enterprise it also provides premises, equipment and training to help people take control of the technology that surrounds us, and helps to recycle unwanted equipment. There’s still a lot to do, and equipment to acquire, but the team of hackspace volunteers have done vast amounts of work. Stud walls have been ripped down, opening the space up again, wood and abandoned equipment has been recycled, and we have equipped a comfy café made up from reused furniture. The major hacking done so far has been to fix a professional coffee machine (using parts taken from a broken fruit machine), some welding, some bike fixing, building a café countertop, rewiring, and making a website. We’ve got four Raspberry Pi computers, lots of donated broken computers which we’re fixing, and our first event coming up.

I now volunteer on a regular basis, and when the coworking space is ready, I intend to work here most days on my own projects and treat it as my workplace, as well as helping to run it as a cooperative member. Not bad for £50 a year – the price to join Open Shed as a member.

Rather than repeat all of the information about Open Shed, visit the website and find out more. We have just launched a crowdfunding campaign to help raise money to buy equipment to further fit out the space, so if you can help (and you’re reading this before October 2012) please watch our video and read our pitch, and donate if you can.

If you’re a self-styled geek, nerd, or are just enthusiastic about technology, and you find yourself in Penzance, Cornwall, drop by our hackspace in Champions Yard (to the right of the cinema on Causewayhead – see Google for a map) for a cup of coffee, some wifi, or join us!