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Difference between 3D Model, BIM, BIM Model, and Digital Twin

3D Model, BIM, BIM Model, and Digital Twins, GIS

Sometimes there is some confusion when dealing with these terms: 3D Model, BIM, BIM Model, and Digital Twin… it happens that one term is mentioned while actually another term is meant…. Therefore, I am trying here to define these terms in simple words.

3D Model

The term “3D Model” refers to a way of representation … Assume we have a building, we can represent this building in a flat two dimensional format (2D), on papers or screens, as a polygon that has an area.

Or, we can add the third dimension, which is the Height… This way, we have a 3D representation of the building as an object with Area + Height… The model can be more complicated by adding 3D models for each buildings elements such doors and windows.

The below is visualization for some buildings in 2D & 3D.

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BIM

BIM means Building Information Modeling … Actually, BIM is not just “Modeling” … BIM is a complete process for creating and managing information related to building an asset (Buildings, or infrastructure networks). This process allows collaboration and sharing information between different stakeholders such as owner, contractor, consultants, Project Managers, and project engineers. Ideally, part of the process is having a shared 3D Model for the asset. So, instead of working on huge number of 2D drawings, engineers work on building one 3D model, then they may generate the needed drawings from the model. This saves time, and enhances the common understanding. There are Software Packages for supporting this process. The most famous one is AEC collection from Autodesk, which includes multiple software programs + Autodesk Construction Cloud, which is a cloud-based platform.

There is multiple levels for the BIM process:

Level 0 BIM: No collaboration between parties. Work is mainly done using 2D CAD drawings.

Level 1 BIM: Work includes a mixture of 2D drawings and 3D CAD models for concept work. Still no collaboration between different disciplines. Each unit maintains its own data.

Level 2 BIM: This is distinguished by collaborative working. All parties use their own 3D CAD models, but not necessarily working on a single, shared model. However, there is common format that allows the exchange of information between different parties.

Level 3 BIM: A full collaboration between all disciplines. A single, shared project model is stored in a centralized repository. All parties can access and modify that same model, and the benefit is that it removes the final layer of risk for conflicting information. This is known as “Open BIM”, or Integrated BIM (iBIM)

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BIM Model

This refers to the 3D model used in the BIM process. Generally, this BIM Model is not just a 3D representation. Usually, it includes information as well. So, each component of the model stores information about this specific part of the asset. When a user clicks on a visual element, a list of data items appeared to display the stored info about this element.

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Visualization and rendering capabilities can be used to give the BIM models an attractive look.

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Digital Twin

Digital twin means having a digital copy of the asset, and this copy reflects the asset in additional to any updates take place for that asset.

For example, a digital twin of a building means we have a digital 3D model for the building, plus finding a way so that updates happen in physical buildings appears on the digital model as well. Question is how to transfer these updates from physical building to the digital 3D model? The answer is Internet of Things (IoT). In simple words, we add sensors in the physical buildings to detect changes that we need to track, such as sensors for temperature, intrusion, motion… etc. Sensors are connected to the internet so that they send readings online. The readings are received, and used to updated the 3D model. Accordingly, this model can be call a Digital Twin.

Why do we need a digital twin?

Digital Twin allows us to quickly understand and analyze the changes at the asset in order to respond accordingly. Moreover, we can use digital twins to analyze “What if” scenarios to study specific changes and their expected impact on the asset.

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Integration with GIS

Integration of BIM model with GIS (Geographic Information System), adds the spatial perspective to the picture. By integration we link each BIM model with its location on earth. In other words, we store the model at its coordinated (latitude and longitude). Accordingly, we can have a GIS map (2d/3d) with the different 3D model. And we use this map for the following:

  • Display BIM models + other data on the same map. For example, we display the models of the new buildings + existing streets, and other old buildings
  • We can apply spatial analytics (such as heatmaps – service areas – buffer zones … etc) to study the relation of these models with the surroundings.

Good news is there is an agreement between Autodesk and Esri, the two leader companies in BIM modeling and GIS. This facilitates the integration between these two worlds. You may view the following video.

You may read: GIS, Cloud and Life.