LiDAR data presented as an image.
2. PRESENT: ARCHITECTURE AND LIDAR
Over the past decades architectural surveying using technological equipments such as laser scanners, LiDAR scanners and other digital tools have become increasingly prominent in the industry. In the last few years, point cloud processing has become more powerful which allows for better management within Building Information Modeling (BIM). BIM is often referred to as the software or computer program used by architects and engineers to simulate the planning, design, and construction of a building. "BIM technologies requires in addition to geometric information, other data, such as physical, structural and functional parameters” (T. Mill et al., 2013, p. 24). Architects and engineers use the BIM software to model a digital copy of an existing or new building to visually show the metrics of the building. Plan view drawings, sections and facades are also generated through the BIM software.
Mill, Tarvo, Alt, Aivars, Liias, Roode, 2013. Combined 3D building surveying techniques - terrestrial laser scanning (TLS) and total station surveying for BIM data management purposes. Journal of civil engineering and management, 19(Supplement_1), pp.S23–S32.
2.2 ARCHITECTURAL GENERATION
Drawing plan views, sections and facades is a standard form of working with, representing and presenting architecture. It is historically a format that presents an abstraction of architecture, which can be easily presented and discussed. Communication in the form of these drawings require that both the designer and the interpreter have the same underlying knowledge to be able to read and communicate using the drawings. While working as an intern, I experienced that there was sometimes a lack of skill in understanding plan view drawings, sections and facades in the AEC industry. The communicative skill of presenting architecture using these drawings also fluctuated. This might be because more and more information in society is being conveyed visually through photographs and architectural renders, rather than drawings.
The change from analogue work to digital work has become a clear divider in the field of architecture. You have those who draw with pen and paper, and quite elegantly manage to communicate through different perspectival techniques and two dimensional drawings. On the other hand you have the "new school" who might not be as skilled with the pencil, but manage a digital model far better. This divide allows room for development in the younger generation, as they may adapt to change easier, due to more exposure to technology, however the older generation is usually the one who has the most experience with architecture. With this being the case, it becomes increasingly important that both generations find common ground to be able to communicate effectively through their BIM models internally but also externally with clients.
As seen in architecture by Zaha Hadid Architects, much of the work is nearly impossible to achieve without the use of computers. The Heydar Aliyec Centre, for example, becomes a building that showcases how parametric design can drive new design forward (Hadid, 2012). Zaha Hadid embodies “the transformation from the analogue to the digital, where the values of both technological models were appreciated and explored” (Fontana-Giusti, 2016, p.97). Only the ability of the designer stops the progress of the way we can design and think. Parametric design thinking becomes a way for architects to design in terms of an incremental progression (Oxman, 2017). Regardless of the initial design process whether it be analogue or digital, what happens if one were to make changes to buildings in the future, assuming that existing drawings are neglected?
If we look at Norman Foster and partner's ICD Brookfield Place, the mere scale of the work begs for computational forces as the thought of drawing 107,542 square meters (Foster, 2020) by hand would simply be unthinkable within the timeframe given. In addition, to be able to repurpose the building in the future for a new intended use in 20, 30 or 50 years from now, architects would require a method of working that is efficient, accurate and different. The existing design will have to be made a part of a larger parametric world, where the parameters of the original buildings can be changed to meet newer requirements.
With the rise in technology, we are in need of discovering a way to use the technology to our advantage. In Oslo, Arcasa Arkitekter together with Seltor and Multiconsult will rehabilitate Kristian Augusts gate 23 from a previously protected building to a new office building (Byggfakta, 2020). The goal is to look at the existing building mass and be able to renovate and rehabilitate the building using 50% of its original resources. Kristian Augusts gate 23 aims to be an example of how repurposing can be done through technological advances. The underlying driving force is that the building sector was responsible for 25% of the 11.7 million tonnes of waste disposed in Norway in 2017 (Byggfakta, 2020). Through a pilot project, they will be able to test and evaluate new ways of working.
To be able to repurpose and redesign buildings designed by previous architectural generations, architects benefit from making use of new techniques and technology that will allow them to efficiently understand the ideas implemented when the building was originally built. Many existing buildings have good qualities that are worth incorporating in a new design, even though the apparent building envelope needs development. Through working with the older architectural generation, who have experience from building some of the buildings in question, the new generation of architects can get a cutting advantage in understanding what makes a specific building great and prolong the life of the building. By adopting to change, for example through BIM models together with scanning, architects have the potential to create an efficient and accurate way of working. However, in order for there to be a new way of working, the framework for redesign needs to evolve.
​
Hadid, Z., 2012. Zaha Hadid Architects. Available at: https://www.zaha-hadid.com/architecture/heydar-aliyev-centre/ [Accessed April 21, 2021].
Fontana-Giusti, Gordana, 2016. Zaha Hadid: 1950–2016. Arq (London, England), 20(2), pp.95–98.
Oxman, Rivka, 2017. Thinking difference: Theories and models of parametric design thinking. Design studies, 52, pp.4–39.
Foster, N. 2020. ICD Brookfield Place: Foster + Partners. Available at: https://www.fosterandpartners.com/projects/icd-brookfield-place/#drawings [Accessed April 21, 2021]
Byggfakta, 2020. Skal gjenbruke 50 prosent. ByggFakta. Available at: https://www.byggfakta.no/skal-gjenbruke-50-prosent-162183/nyhet.html [Accessed April 21, 2021].
2.3 WHAT IS LIDAR?
LiDAR is an acronym for Light Detection And Ranging. It is used in applications for surveying, geodesy, geomatics, archaeology, geography, geology, forestry among many others (Cracknell et al., 2007). In short, LiDAR uses ultraviolet, visible or near infrared light to image objects (Cracknell et al., 2007). Wavelengths are emitted from a device, moving to an object and reflected back. The time taken for the light to come back determines the distance. The most common LiDAR scanners also capture a photo of the objects which then gives the registered points color. The distance to objects and its color is the information that becomes valuable within the field of architecture as this can form the basis for architectural modelling.
Cracknell, Arthur P, and Ladson W. B. Hayes, 2007. Introduction to Remote Sensing. London: Taylor & Francis. Print.
2.4 USES IN ARCHITECTURE
LiDAR has been used in architecture over a period of time due to its ability to accurately represent an existing situation. The scanning technique started in the early 1990’s (Fritsch & Klein, 2017). Now, reality-based 3D modeling has become the basis for uses such as material production, restoration and conservation policies (De Luca, 2014). The complexity of heritage sites, for example, deems for advanced analytics to be able to reconstruct and safe-keep the cultural history in a heritage site through precise measurements and registration. The starting point of having a scan is vital to making a functional digital model that works well with analytics. The scan allows us to be able to reconstruct surfaces based on what is missing from the current design. De Luca (2014, p.116) states that “It seems essential today to examine how quantitative information (extracted from surveying) and qualitative information (produced by interpretation of data acquired during the analysis of documentary sources), can be analysed and displayed within a unique integrated platform”.
Using BIM or other digital models becomes a way to compound information about a specific site to be able to study it accurately, and through a longer timeframe than if one were to study the project on site. Due to the accuracy and efficiency of LiDAR scanning, the technology has been used increasingly to survey existing situations and use this to model new architectural projects. The information obtained from a scan is available to be accessed and used at any point in the architectural design process.
Fritsch, Dieter et al., 2018. 3D preservation of buildings – Reconstructing the past. Multimedia tools and applications, 77(7), pp.9153–9170.
De Luca, Livio, 2014. Methods, formalisms and tools for the semantic-based surveying and representation of architectural heritage. Applied geomatics, 6(2), pp.115–139.
Screenshot showing what point cloud file looks like from ReCap Pro.
The image above portrays how a point cloud file looks like when opened in a post- scan software called ReCap Pro. The LiDAR scan, delivered in the format of a point cloud, gives a reference of the existing building with Red, Green and Blue (RGB) colored dots representing the colours and distance to the objects recorded by the scanning device. When having imported the point cloud into a post-scan software, the point cloud can be viewed in space and the points can be measured. The ability to “fly” through the model allows the users to acquaint themselves with the building through the scan. The point cloud samples can at times be very dense as there are millions of points in one file, because of this, there is often a need to reduce the file size for the point cloud file to be used efficiently with BIM. This process is called to "decimate" the point cloud. The points are also often put in layers, organised by floor plans to make them easier to handle within BIM. BIM has the ability to work with layers and you can then hide and make visible the layers needed in your current view in BIM. The information obtained in the point cloud model can then be used to make a replica in a BIM modeling software by importing the decimated point cloud into the BIM software.
Screenshot showing BIM through Archicad (BIM software), using a decimated point cloud in reference to modelling an existing situation.
The image above shows how the point cloud can be incorporated within the BIM model to consistently have a reference to work with. The dots seen in the image above is what was originally scanned by the professional LiDAR scanner. The other smoother surfaces seen are native BIM elements. BIM elements and objects hold physical as well as visual properties. This means that the wooden flooring, for example, has a thickness of 19 mm, made with oak, and the width of each floorboard is 130 mm and so on. Heat transfer coefficiency, fire resistance and sound absorption are also included as parameters, among many others. The types of materials and how much of it is used is instantly calculated and becomes available to easily extract if this information is necessary. This means that in a BIM model you have a lot of information about the specific elements in the project that would only be applicable to include in some certain drawings. To give an example of this, the fire resistance of doors, walls, floors and ceilings might just be included in a fire plan and section drawing. In terms of future repurposing, this is information that can be very useful to be able to determine the quality of the materials used. Architects and engineers can produce all necessary design drawings, constantly being able to view the existing situation by viewing the point cloud that is integrated into the BIM model. This makes it easier to track changes and see how the building was to begin with, which is important when rehabilitating existing buildings.
2.5 LIMITATIONS OF LIDAR SENSORS
Architecture is experienced through a variety of our senses. The senses of sight, touch, smell, taste and hearing all account for the perception of architecture. Sight, however, is the prominent sense when experiencing architecture. This also translates to how LiDAR works. It makes use of the visual sensory system to record space by showing what is visible.
What becomes important to remember when scanning, is that a LiDAR scan only captures the immediate surfaces seen. What you then get is the surface on both sides of a wall, which embodies how the interior spaces are together with the surfaces. However, the structure of the building is left blank in the scan as the structure is not visible and therefore not registered. This becomes important to understand as the structure of the buildings is often how we can determine how and if we can use the structure in a transformation project. Therefore, unless there is an archive with an existing BIM model or an accurate set of construction drawings there is still a need for a qualified inspection on site to determine how the building was constructed and if the construction system is adequate for a transformation.
Due to the LiDAR sensor working with light we also need to be aware of certain limitations that comes with using light. Windows, mirrors and completely black surfaces will reflect and refract light in a different way than most materials. Windows will allow for light to travel through, essentially recording the distance out the window until it is stopped by an object on the outside of the window, depending on the range of the LiDAR sensor. Mirrors will reflect the light, making the length double as the scanning position is seen “behind” the mirror. Lastly, completely black objects will absorb all light, not allowing the light to reflect back to the sensor.
The major downside associated with LiDAR scanning when using professional equipment is the price of the service due to the high price of the equipment. The cost of labor adds to the already steep price.
Plan view of a scan. Showing the surface of walls and ceiling. Unscanned areas are shown in white.
2.6 PRECURSOR TO MOBILE LIDAR
As a precursor to LiDAR on the mobile phone, photogrammetry was used to make digital models from photos. In 2019, Xiau Pan wrote an academic paper on the use of mobile phones for texture-mapping and digitisation of an object. He used photogrammetry, which is a method of taking several photos of an object and using the information stored within each photo such as the aperture, exposure and shutter speed, to be able to make a digital model of a plaque (Xiau Pan et al., 2019).
Photogrammetry has been used for some time to document and register archaeological sites to be able to make digital replicas. However, the process requires many photos, and the process can be tedious, yet important in order to reach the desired accurate outcome.
Technology advances quickly, as seen for example with cameras on phones, from barely being able to see what was photographed to where it is now preferred by some professional photographers. With the introduction of the LiDAR sensor on the iPhone 12 Pro in 2020, I was curious to see if I could use my knowledge within architectural softwares to determine how the design process could be affected and if so, the outcomes of this. I wanted to test if LiDAR on a mobile phone could be used similarly to that of a professional scan. Knowing that the technology is at an elemental stage of its development, it was interesting to test and see how it could affect architecture.
More about this topic is found in the chapter 3: NEW ERA.
Pan, Xiau et al., 2019. RESEARCH ON INFORMATION ACQUISITION AND ACCURACY ANALYSIS OF ANCIENT ARCHITECTURE PLAQUE WITH COMMON SMART PHONE. International archives of the photogrammetry, remote sensing and spatial information sciences., XLII-4/W20, pp.65–70.
2.7 SUMMARY
-
Existing building application drawings and other available documentation may deviate from what is actually built.
​
-
LiDAR presents itself as a tool that is precise and efficient in being able to measure and depict what has been built. This information can be used to make a BIM model.
​
-
It is important to combine technology and new practices with the experience from those who have worked in the AEC industry for a long time.
​
-
LiDAR can present great efficiency in the way architects work, but one also have to keep in mind the limitations of LiDAR technology.
​
-
LiDAR is now available on mobile phones which presents an interesting opportunity to investigate new ways of working.