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Chris Thompson, Research Engineer, BSRIA Sustainable Construction Group
Built2Spec is a EU funded project that aims to bring together the latest in self inspection, 3D modelling, management and quality-check tools for construction to unify various techniques through a virtual construction management platform (VCMP). The VCMP system will support the collection and sharing of all project data from the initial design through to completion.
BSRIA has been involved in determining the requirements to integrate thermal inspection techniques with a VCMP system by looking at the technology involved, training specifications, systems operation and identifying potential limits for both now and in future.
The general idea was to create a platform for a construction worker with limited training to perform quality checks using a thermal imaging camera. The results would then be uploaded on the VCMP system so that the progress of construction could be easily monitored. Figure 1 illustrates this idea of the thermal imaging self-inspection system.
Some of the main areas in need of development are outlined below as:
The ability to determine the location of the thermal imaging camera is key to the success of the system. The system put in place to do this would need the location to be as accurate as possible, locating the position, the field of view (FOV), elevation, orientation and distance to the object being imaged.
Many systems such as Structure, Google Tango tablet devices and Bluetooth Low Energy (BLE) technology for smartphones were researched to fulfil this purpose. The BLE system would use BLE devices located around the building from which a Bluetooth enabled device such as a smartphone could receive the signal and determine its distance from each BLE device. BLE has its limitations as it relies on comparing signal strength between beacons to estimate distances from each, but the signal strength can also be affected by building components and features that intervene and by materials that cause reflections. The BLE systems accuracy may prove too poor to make it useful for camera location system so it was concluded that further research would be required. Google Tango or Structure could prove useful as they can provide accurate orientation and direction due to their 3D mapping capability.
Thermal Imaging Device
Currently, a qualified professional equipped with an expensive thermal imaging camera, is essential to take good quality, high resolution images and determine what is shown in the images. Having a qualified thermographer present at multiple stages during the construction process would be very expensive, therefore, the possibility of having a site worker take the images was explored through this project.
See BSRIA's range of thermal imaging cameras for sale and hire
The Flir One model cameras for smart phones (figure 2) were researched by comparing the cost, technical specification and performance with a mid-range thermal camera, the T360 from Flir. After multiple tests, it was determined that the Flir One would be suitable for basic quality checks such as correct installation of insulation. The Flir One could also take advantage of the smartphone features such as being able to take a composite panoramic image shown in figure 3, along with the added functionalities of a smartphone which would help simplify other aspects of the project such as sending and receiving images.
BIM and Thermal Modelling Software
Thermographers often have a problem in determining the building fabric composition being imaged which could be solved by connecting BIM models and thermal images for analysis and quality inspection. With a location system working alongside the thermal imaging system, the images could be located on the building model making comparison easier. This process could be improved further by feeding the environmental data collected on site as input to the building model using the dynamic thermal analysis software, to create a site-accurate 3D thermal model. This thermal model could then be compared to the thermal images via location system placement; however, the software to perform these functions does not exist yet.
The Built2Spec project is advancing the boundaries of construction practices. Some goals such as using smartphone cameras for quality inspection maybe achievable in the short-term while others such as implementation of a complete system which would change the process of construction management are long-term. This will help the industry realise the potential of new technologies in construction practices by bringing together different areas of the process of building a centralised system leading to more efficient building construction.
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