Digital Twin Using reality Capture

Desapex

This book is not going to be philosophy book of digital twin but, it will explain the step by step process of creating digital fabric of built environment ( buildings, factories, warehouses, estates, villas, metro’s etc ) and use it for numerous use cases , which by definition is Nth dimension of information model.

BIM as per NBS UK is defined as below

BIM or Building Information Modelling is a process for creating and managing information on a construction project across the project lifecycle. One of the key outputs of this process is the Building Information Model, the digital description of every aspect of the built asset. This model draws on information assembled collaboratively and updated at key stages of a project. Creating a digital Building Information Model enables those who interact with the building to optimize their actions, resulting in a greater whole life value for the asset.

So, with this definition of BIM , one can easily relate that digital twin to some extent is the subset of BIM provided that life cycle use case are defined and executed during the CAPex to OPex handover stages of construction project , and the only thing where it gets differenti ated from any other 3D models/2D drawings is the real time connection to the physical twin , which expands the horizon of digital adoption in built environment. This is not only limited to the data during design and construction but the capturing, storing and analysing the data during the operation stage of the asset. And this have been evident in the Gemini principles which is the basic framework for UK NDT (UK National Digital Twin Program )

Digital Twin

When the VR /AR technology entered the AEC space there was a similar dilemma and still there are lot of grey area’s as to how one can utilise the technology in a tangible manner and what are the use cases. And with digital twin this dilemma is only getting larger and more broad discussions are happening in the AEC industry to determine the use cases of this framework. When we say broader it might be City level use case and building level use cases, but for all these frameworks to be implemented we need to further breakdown the implementation process into the source of data generation and the way the data get stored, whether it might be static data or dynamic data.

Also, in today’s scenario the digital twin perception is all dependent on the hardware and software technology which are readily usable for certain use cases in the Built environment. For anything which goes beyond the readymade solutions, there is lot of integration and backend processes which needs to be developed, and this changes case to case depend ing upon the user business objectives. Whether it may be BIM or Digital twin , we advise our client’s to take use case approach for digital transformation, because we have seen multiple projects where the use cases are realized or changed during the project execution stage ,which is good at one end but the efforts and the framework gets disrupted.

As a steppingstone towards the journey of digital transformation in the AEC industry, we at desapex believe that the use cases of Digital Twin can be broadly classified into 2 aspects for a built environment:

1 Static Use Case Dynamic Use Case

To clearly understand the subject and to focus on the initial process of creating data fabric of the building this book is focused more on the static use case , which is the preliminary step for second use case.

Static Use Case: In this scenario we will create the as-built data using reality capture technology for operational planning and continuously update the data for future expansion or modifications of the asset. This includes both digitalization of device database geometric and non-geometric. Generally, these are the design data points or the baseline parameters of the particular asset.

This static structured data plays a vital role in creating the digital data fabric required to perform various ongoing planning in the facility, like for example for a Corporate Real Estate Asset

Geometric Twin using Reality Capture Process

Let’s deep dive into the process of creating geometric twin using reality capture process

Step 01: Plan the site

We first take initial plans and the mark all the areas which needs to be scanned and create a schedule of scan and the pathway for the scanning activity, this process helps us in planning the scanning activity efficiently and capturing maximum information during the site survey. The number of scan points depends upon the clear sight of view, if there are more partitions or obstructions generally the number of scan points will increase, also in some of the spaces where ceiling’s must be removed to capture the above ceiling services

Step 02: Scan the Area

After the planning, our team of site surveyors will visit the factory to scan to factory layout during this process our team will be carrying the TLS units along with manual measurement and georeferencing devices to scan and calibrate the data, the schedule of the scanning depends on the size and sight of clear view in the area, if there are more obstructions, naturally the number of scans will increase. Generally, a typical medium level scan will take 4 minutes to scan the given location with mm accuracy.

Step 03: Processing the Data

The point clouds generated of each scanning position are merged and transferred in the same coordinate system, using specialized software tools, in a process that is called Point Cloud Registration. After removing the unnecessary points of the surrounding of the building, the point cloud is ready for use from the client, or for further processing to produce the 3D BIM Models. So for example a building or particular facility might have a 1000’s of scan points but, during this step we will merge all the data and create it to one building or one area file which can be easily linked into modelling tools.

Step 04: BIM Modelling

Once we are done with the processing, we publish the data into a cloud server where our clients can perform their virtual site navigation and track the construction progress or use the BIM model documentation as as-built , in this step ,we link the point cloud data to model all the elements and classify the point cloud data into BIM Model elements. This process includes use of semiautomatic plugins which understands the surface data and identifies the point cloud into specific objects , but also some manual interventions to add the exact data related to building geometrics and non-geometric data , this becomes the data library of the building with object linked into it.