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The work was completed by a two-person team over three nights, minimising disruption to the client, while providing high quality inspection survey information that is now accessible via any authorised PC.
L&M’s Spheron SceneCam solution was chosen as the best tool for the job because of its unique combination of a 32-bit High Dynamic Range (HDR) SceneCam camera and battery powered ScanLight lighting system, which enabled capture of all the detail present despite the complete darkness.
The company’s HDR technology is able to manipulate and store all colours and brightness levels visible to the human eye and beyond, resulting in a greater level of detail and clarity.
One of the main issues with traditional digital photography imaging in rail surveys is that there is usually a need for an extra light source, which limits colour range, constrains luminance and narrows contrast banding, all of which can result in losses of information.
L&M‘s HDR SceneCam cameras used for the East Midland’s tunnel survey avoided these issues by imposing pixel precision detail that represents all the brightness and colour information for every single pixel.This avoids loss of colour vision in dim conditions and much higher levels of contrast between different objects, resulting is real-world images that are brighter and more colourful than LDR, even in complete darkness.
The HDR SceneCam camera used during surveying of the East Midlands tunnel recorded image-pairs every ten metres at chainages, which had been marked out with survey chalk and referenced to a mile-marker, located just outside the tunnel.
Three image locations were captured simultaneously and the cameras then moved on to the next three locations. The SceneCam images were supplemented with additional images from a standard frame digital camera.
The SceneCam images captured the whole tunnel environment and the standard frame camera captured sub-surface details such as the insides of catch-pit chambers and covered cable-housings.
L&M’s SceneCam camera captures a single, continuous image around a full 360 degrees in the horizontal and 300 degrees in the vertical, using a slit aperture and a fish-eye lens.
No stitching of images was required. The camera captures 26 F-stops simultaneously.
In daylight this would capture all the lighting conditions present, allowing the viewer to look into the darkest shadow, yet still remaining detailed in the brightest areas.
On this occasion it allows the viewer to brighten the data from dark conditions to a detailed, vibrant data-set.
Another major benefit of L&M’s SceneCam technology is that no processing is required and the spherical images are imported directly into Spheron’s own SceneCenter software. This software is used to prepare the deliverable for the project – a complete visual tour of the tunnel.
The spherical data set was added to by importing the additional images and then PDF drainage reports of the catch pits and other reports too, all of which can be viewed within the software.
Once complete, the report allows the viewer to navigate through the tunnel in a similar way to Street-view. The viewer can increase the brightness, zoom in, open reports and also – uniquely – measure dimensions directly from the images (possible due to the capture of stereo-pairs on the same location).
Being able to take dimensions from anyone’s desktop means more efficient use of time and reduced schedule on site. This can improve productivity by around 20%, equivalent to adding an extra day’s work for each person.
Alasdair Kirkwood, Commercial Director at L&M Survey Services, said: “Our HDR SceneCam Cameras and content management software can be used for a wide variety of roles in the rail surveying sector. This includes dilapidation and inspection services, VR content capturing, 3D from photogrammetry, site familiarisation and documentation.”
He added: “The technology provides a very cost effective and efficient solution for general onsite scene documentation as well as simplifying onsite communication details by linking high quality pixel visualization technology to real business asset data.”
There are also important health and safety benefits for clients that choose L&M’s HDR camera and software technology because it enables company’s surveyors and its clients’ personnel and their project partners to familiarise themselves with the site access points and track conditions from the safety of their desks, before they try to find, park and access in the middle of the night.
