Tag Archives: blk360

Scan Survey: Les Grandes-Serres de Pantin, Paris.

  • 23&24 -10-23
  • Leica BLK2GO SLAM Scanner / Emesent Hovermap ST / DJI Mavic Pro
  • Multiple scans / 2 Days
  • Rendered with 3DS Max/V-Ray/Arnold, Houdini/Mantra, Leica Cyclone 360
  • Visit: Les Grandes-serres de Pantin (French)

A visit to a vast disused factory in Paris before it is demolished. The old Pouchard Tubes pipe factory was a historic industrial site in Pantin, a suburb of Paris. It was founded in 1927 by the Pouchard family, who specialized in cold deformation and surface treatment of steel tubes for various applications, such as automobiles, boilers, and railways.

The factory occupies a large area between the railway tracks and the canal de l’Ourcq, and has distinctive glass-roofed halls that gave it the name of “Les Grandes-Serres” (The Great Greenhouses)

The factory itself closed in 2017 and the site acquired by a real estate developer with plans to transform it into a mixed-use complex with offices, services, shops, restaurants, and a hotel.

Prior to commencement of the redevelopment the premises were made available as a huge artist space for exhibitions and installations; this scan survey was carried out in cooperation with “Boite à tubes #1, Grandes-Serres de Pantin, 2021”, an electroacoustic work on the industrial sound memory of the site.

The installation was created by Nadine Schütz, a Swiss artist who works in sound and space. She created the work in collaboration with the artist collective Echora.

The sound installation itself is located in a small control cabin in the Grande Halle of the Grandes-Serres which has been perforated with a variety of metal tubes of different sizes. Each tube plays a different sound, creating a cacophony of industrial noises which act as powerful reminder of the industrial past of the Grandes-Serres site.

While the many lime trees that surround the site cannot be relocated, the intention is for their sculpture-grade wood to be repurposed within the new development.

Scan Survey: Greenwich Foot Tunnel

The foot tunnel beneath the Thames connecting Greenwich in Southeast London to the Isle of Dogs.

  • 27/7/22 : 5.00AM
  • Leica BLK2GO SLAM Scanner
  • Single scan / 20 minutes
  • Rendered with 3DS Max / V-Ray

The tunnel was built in 1902, is 370 metres long and 15 metres deep.

The south shaft has 100 steps, the north shaft is a little shorter with just 88 steps.

A section of the tunnel was damaged by a bomb on the first night of the blitz during the Second World War in 1940. The repairs included this exposed metal ring segment.

Creed Monument – Scan Techniques

The monument of the Creed family sits against the North wall of St. Alfege Church, Greenwich. Sir James Creed (1696 – 1792) was an MP and lead merchant and is buried with his wife at the church. This is a marble monument, about 4 metres high – with markings higher up that suggest a metal cross piece used to be fixed to it.

Photogrammetry Scan

By photographing an object from all sides and capturing many images – with enough overlap so they can be tied together – photogrammetry software can create an accurate 3d model of that object. The resulting mesh object can then be edited and used in CAD / 3D modelling software such as 3DS Max, Rhino, Maya etc. Processes could include replacing textures / materials or applying sun and light models to examine artificial shadow patterns.

This model was created with the software Zephyr Aerial 4.5 using 64 photographs taken with an Apple iPhone X in good daylight. The clarity of a high definition photograph enables the model to carry over very fine, close up detail. Zephyr allows for the mesh to be tidied up, cropped and then exported to the Sketchfab website / service which allows models to be zoomed, spun and examined via browser or app (embedded link below).

Photogrammetry lends itself particularly well to constructing museum-grade scans of smaller, closer objects. It can also deal with larger projects though these are likely require the use of extra equipment – drones, zoom lens, etc. – to obtain distant, high up and otherwise hidden spots to sufficiently cover the entire subject.

Creed Monument: Photogrammetry

Laser Scan

LIDAR technology – radar with light – bounces many light rays off objects within a space to measure distances to those objects and build up a cloud of points with accurate spatial data that represent the shapes found. Typically a tripod mounted laser scanner will rotate the beam vertically and the scanner unit horizontally to capture a 360 sphere of data in a single scan. A number of scans are carried out to best capture the space from all points – and eliminate “blind spots”. These scans are combined together – or registered – to create a single unified point scan.

While the density – and size – of the points can give the impression of solid geometry it is important to remember that this model is floating dots – not solids or meshes that can be edited in the same way as the photogrammetry final output. The size of these points can be adjusted to create revealing, x-ray style views through a building. More practically a point cloud survey of a site can reside as a reference layer on a CAD site plan; the very fine accuracy of a laser scan and the distance it can reach being a distinct advantage.

A Leica BLK360 scanner was used to carry out this scan – with three scans about the monument registering into a single point cloud. Each scan takes around 5 minutes and with so few scans the registration process is straightforward – large projects with lots of scans can be a very involved and time consuming process.

Relative to other laser scanners this model has a range of “only” around 50m (the Faro scanners have nearly three times this). The high concentration of light points sent out also mean that – even with tree coverage around a building or landscape – enough of the beams will still get through to record the semi-hidden project behind.

Creed Monument: Laser Scan

iPhone Polycam App

The Apple iPhone 12 Pro and iPad Pro include a Lidar sensor – a feature to enhance the accuracy of distance and measurement for purposes of augmented reality and camera focusing. This feature has also been utilised by a number of developers to create Lidar scanning apps which open up the opportunity for quick, on-the-go scans straight from the phone.

This app by Polycam is one of the earliest and best to exploit the hardware and point to possibilities of this handset based technique.

This is a lower resolution mesh but the high resolution images wrapped around it still give a good impression of the model. Polycam / Lidar sensor will continuously try to correct itself during the scan sweep to maintain alignment – but there are a few tears in this example where the registration has slipped. More careful movement when scanning would help to prevent this. This scan took about 5 minutes.

Creed Monument – Polycam Scan / iPhone

iPhone TrueDepth Apps

Recent Apple devices use the front facing camera – with “TrueDepth” sensor – to capture 3D information for use with face ID authentication and Animoji. This technique involves projecting 30 000 infrared points and reading back a 3d map of the user’s face. Similar to the Lidar apps, developers have utilised this feature to author apps that can 3d scan with it.

Heges and Capture by Standard Cyborg are two good apps that lever this power of TrueDepth to carry out 3d scans.

Although the capture resolution here is very high the range is short which makes it suitable just for smaller, close-up scans. The other big barrier is that since it uses the front facing camera the handset needs to be pointed at the subject – with the screen away from the viewer. This can make it difficult to see what areas are being scanned – though the Heges app does include a screen share feature where the scan view shows on another device. Constructing a rig that can rotate the camera smoothly all around the model is another option too, where possible, to control speed and shake.

St Anne’s Church Limehouse

A Nicolas Hawksmoor church started in 1712, completed in 1727 and consecrated in 1730.  Part of the 1711 act of parliament to build 50 new churches in London. Twelve – known as the Queen Anne Churches – were built, with six designed by Hawksmoor.

The tower of St Anne’s Church was originally designed for a rebuilt St Alfege Church in Greenwich however, as a cost saving measure the original St Alfege church tower was retained, and the new tower design went to St Anne’s instead. 

The approximately 50m high tower was designed to be visible from the Thames and protrudes well above the canopy of surrounding trees in the churchyard.

A large pyramid sits in the churchyard with the inscription “The Wisdom of Solomon”. A Hawksmoor elevation from the British Library shows a design with two pyramids on the east towers that were not built suggesting it could be one of two intended for there – though these are much larger than the one in the churchyard.

Further Reading / Sources

The National Archives

St Anne’s Restoration Campaign

St Alfege website

Londonist Article

Severndroog Castle Laser Scan

Laser scan / point cloud

Severndroog Castle – “Lady James’s Folly” – is an eighteenth century tower located in Oxleas woods in Southeast London.  It was built as a memorial to Commodore Sir William James, a former chairman of the East India Company by his wife Lady Anne James in 1784. Designed by architect Richard Jupp and based on Shrubs Hill Tower in Windsor, the triangular tower is 19 meters high with three storeys and a viewing platform. It stands within ancient deciduous woodland at the top of Shooter’s Hill – one of the highest natural points in London.

An inscription on the stone tablet above the entrance reads:

This building was erected MDCCLXXXIV by the representative of the late Sir William James, Bart. To Commemorate that Gallant Officer’s Atchievements (sic) in the East Indies during his command of the Company’s Marine Forces in those seas. And in a particular manner to record the Conquest off the Coast of Malabar which fell to his superior Valour and able Conduct on the 2nd day of April MDCCLV.

Survey Details
  • Laser Scan
  • Leica BLK360 / 13 scans / Medium scan density setting
  • Early morning / May / Sunny weather / significant tree coverage
  • All scans from ground level, external
  • Registration: Recap iPad app / Recap Pro 2021 desktop application
  • Post processing: CloudCompare / 3D Studio Max 2020

Export from Recap Pro as .PTS file

Clone instances of these imports and apply different subsampling settings to vary density of castle vs trees. Blend the results

3D Studio
Real World Point Size: 0.05 | Quality 2

3DS / V-Ray to render of point cloud – vary settings of Real World Point Size and Level of Detail

Real World Point Size: 0.01 / 0.02 / 0.05 | Quality 10
Orthographic – blended point sizes
Zephyr Aerial

Generate Orthophoto from dense point cloud

Further Reading / Sources

Official Severndroog Castle Site

Ian Visits: Climb to the top of Severndroog Castle

The Folly Flâneuse

Historic England

London Gardens Trust