www.youtube.com/.../watch?v=4AcB18Y7cgw

So now that we ...

... I'm a programmer ..

... I hope that we're going to get a bigger soon ...

We specialise in masonry. Masonry bridges in particular.

We do a few other bits and pieces, but the core is basically bridges.

We're always looking for new ...

Sorry!

...

Hopefully that doesn't trouble.

So I think we're looking for ways to understand damage better, and in masonry that is an interesting task.

And in the last couple of years we've done a lot of work on developing photogrammetry

which we believe has the potential to transform inspection and assessment of historic bridges ...

... and all masonry bridges ...

But really all masonry bridges are historic bridges.

I don't have to tell most people here, I think, about photogrammetry, so I'll cut out all my usual slides.

The basic process is you take a lot of photos, with lots overlap ...

... compress them down into a model and then you profit from the results

Reality is obviously a bit more detailed.

I'm not going to talk about processing a basic trick that we have here ...

... is big workstation and reality capture. Which is fantastic.

Taking photos is more of an issue, and how you get information out of the data that we produce is the second part.

A couple of case studies.

Pontypridd Old Bridge was built in 1750.

It was the fourth attempt that Williams Edwards made.

He was given a 7 year contract to cross the Taff at this point.

The first attempt was a 3 span washed out by floods.

He thought, well sod that. if I'm going ... to go in 1 step

That one, the centering collapsed before the bridge was finished.

Not being put off, he did it again, did the centering a bit better.

Successfully structured the centering.

Six weeks later the bridge collapsed.

And it collapsed in a particular way

with the crown bursting upwards and the sides going in.

So he then gathered a little bit more money together from the gentry of the area

who must have been quite ...

... he must have been quite compelling, or maybe it was the fact that he was a well respected preacher.

Well he must have thought so anyway.

He gathered these transverse tubes at the sides of it where it's out ...

... and if you look at the top of it you'll see there's a partition ... at the top ...

... and it's been there since 1786.

100 years later they built this bridge along the side, that's been widened since.

And now it runs to about half a meter from the circle ...

So since 1850, or it seems, the south elevation ...

Capturing photographs of this, what we're aiming to do is to get set sub-millimeter detail from the whole structure.

It's big. It's 43 meter span. It's all rubble masonry, basically lots of roughness, lots of detail.

The crown is about 10 meters off the water.

Victoria Bridge is very close, which ...

And at least there was a ford here, so in the driest summer in recent years it was certainly possible walk backwards and forwards underneath.

And we ended up with 14,000 photos.

That's taken straight from reality capture. And reality capture can take 14,000, or indeed up to 30,000 quickly photos.

And align them.

30,000 took me within a gnat's whisker of 256gb of memory.

But it just does it.

And you finish up with a model that allows you to step back and look.

This is the south elevation. No-one has seen that for 170 years.

In this view ...

... 5 million triangles with a very high detailed texture that ...

... mesh means that the texture is just slightly blurred on these rock surfaces.

But we can zoom in and see cracks, and we can see details that we wouldn't really understand without the photographs.

... for bridge inspection is much a detailed photograph site as issue here.

Forced out.

And so being able to understand that damage in context is pretty good.

Being able to read the full photographic elevation of light to measure things.

And we can zoom in to have a look.

For some reason, it's not quite as good on the software, which is annoying ..

.. but this allows you to see ...

... it's still pretty good. You can see individual bits ...

A bit on collection.

We don't use drones.

We don't have the scale to justify having the the utilisation that justifies the licensing costs.

And anyway, I've yet to come to a bridge and find that half of it is only accessible to a drone.

No trees. There's not a bridge next to it. It's next to traffic ...

It will be useful for the some bits of it ...

.. but we don't have to deal with this stuff anyway.

So there we are ... standing in the river we've got some mud weights attached to the bottom of the pole for balance.

And we can get it to about 8 meters.

Different bridge, and we can stick it out over the side.

...

And we have camera rigs.

So this is set of Sony QX1 cameras all strapped to a 6 meter beam.

The triggers are powered on a wire so they trigger almost constantly ...

... they're carbon batteries, so there's always one that's running out of battery.

You can't take it in and change the battery if it's tied a beam.

... Here you could walk into the swinging ...

... rigged up the Sony to the side ...

And why bother? It's a lot of effort. But ...

The ability to zoom in and see that detail, and then step back and see where it is.

I keep doing that in the office ...

... where it's warm ...

It's just unnatural.

The problem is we get a lot of data.

We don't need the data. We're looking for understanding.

Just having the model is a step forward.

We have a point cloud. You've got a vast amount of data ...

... you can convert that into a mesh, and bring the data level down and get more access.

Photogrammetry gives you a bit of a much better place, and just having the model to look at is good.

But we need to do more to interrogate them and extract information to learn the stories we have to tell

and then we also need to share those stories with other people.

So we've been working on a viewer with a few simple tools to help us take the model and say what's going on here.

A very quick at an an 1830s canal bridge and then a bit of a bit of a look at a Clifton suspension bridge.

One slightly sad bridge, and also very faint.

It's just a standard canal bridge. You can see cracks here.

About an hour on site and 2000 photos got us this and gave us this level of detail, where we can see into every crevice

we can see all those lost bricks, and we can see how this bit dropped here.

And we can look around it.

So far, so good.

But we need to understand what's happening. Why is the brickwork here? What's going on?

And what we can do with the viewer is ...

We know there's something funny about the crown. Let's put in a horizontal plane through the point.

And it gives us an imaging contact.

So this is used for the shading engine.

We can see the intersection. We can see that it's lower here. That there's a ...

... at this point.

At this end there's also mould, but not nearly to the same extent ...

... and all of that lets us start to get an understanding of what's going on interactively.

So we can contour this. We can say we've got a mesh, we're going to do a set of contours.

We've got to decide what contours and what spacing.

With this ...

... and play and move it around and see what it is and then go and start producing your contours.

...

This is the Clifton suspension Bridge. You may be familiar with it.

Clifton's over on this side, and Leigh Wood's over here.

This buttress built up about 10 years ago.

Somebody doing some maintenance on the deck lifted a stone up and realised oh there's a big hole here.

There's a shaft that goes down and they looked up and -- from there -- they could see that the shaft goes right down to the depths of the buttress.

And obviously they explored further and discovered that around the shaft there's this whole network of vaults.

So the road comes up over the river, runs along the central vault, and there were these two at the back and off the line.

And nobody had thought, that's a massive abutment ...

But once you know they're there you have to expect them. You have to know you're safe.

Out of sight, out of mind.

Just out of interest.

We've got a laser scanner there. This was early in our photogrammetry exploration. We didn't know if it was going to work in pitch dark.

So we needed the geometric information as well, and we got the laser scan, we got 45GBs

converted that into a textured image

200MB that we can load onto a normal PC.

These models are about 200MB as well, per vault.

This is ... we come in through this tunnel, past this shaft, having gone up another tunnel ...

... coming in from the other level through a ladder in the shaft ...

...at my height you have to remember to put your hand up before you get into it because you can't move your elbow.

We find if we look at the bottom bit and turn it around ...

... we've got these things that throw cast iron ties into the walls ...

... that have been there since this was finished and closed. And they're is packed with timber.

You can see there that they were vertical timbers, with just a bit missing in the middle.

This one was filled with water before the others were discovered.

And it was obviously a very stable level. It's moved up and down by about a foot.

And the timber has rotted where that's happened and there's now coral down there ...

You can look up the top and view along these things which are 10 meters up in pitch dark

and you can see that tie is shining quite brightly.

There's no attention to it.

If we look to ...

... we can see a crack.

We couldn't see that until we looked at the model.

There's no way ...

... that by the time you've wriggled into that space, shining a torch ...

... that you're got to catch features like that ...

... but once you got this you can look at and take your time with about, you can see things that you wouldn't see otherwise.

We can move the plain across here as well.

And ... the plain.

I've set that to just roundabout about springing where the whole starts turning in.

You can turn it over clipping plain and change the clipping direction.

You can go to photographic ... view from below.

And then next to him ...

... colouring.

So if we take a normal vector for every triangle and cover the mesh with that, we can very quickly see changes in matter.

So you can see that although the shape of the bottom planes have curved sides and corners that is carried right onto the bulk of the top.

But we can also see very quickly that there are orange stripes all the way around here

...

So we can start to learn that the walls are built quite easily once we got to the top and built freehand as far as we could.

Because working up there, if we built a center...

... you'd be fighting trying to work out ...

... and you stand at the platform ...

and only at the very top do you put the center in and finish it.

So you can see that it's smooth at the sides. Smooth at the top where the wood would be worked on ...

... there's always roughness in ... masonry.

And there are interesting things like this.

These stones were embedded in the stones. The stones actually slipped forwards as they were building it.

We're going back there next week to do the top level.

So those models are of the bottom, and we're going to back there and do the top one.

I'm a bit nervous about that ...

...

I've been developing a bit of extra kit to try and speed up the process and not just go like ...

So developing an understanding of defects is really hard.

Textured meshes are a lot more useful than point cloud in this respect, and that's not just if you're in the dark.

It's possible to get sub millimeter details for very big structures ...

And being able to take snapshots in time at very high detail gives you an ability to rethink

... whether it's just because you've thought of something and you need to go back and have a look

or because you're looking at it again for a second time.

Thank you.

[APPLAUSE]