Five types of urban digital twins

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The definition for urban digital twins is too vague — so it is important to create a clearer picture of the types of urban digital twins that are available. Not all digital twins are the same and each one comes with features and capabilities, strengths and weakness, as well as appropriate and inappropriate use cases. Based on my recent presentation of my SIMO software at the Smart Cities World Expo in Barcelona (tinyurl.com/Smartexpo) and many exchanges with clients, customers, designers and project managers, I believe it is time to create a better understanding of urban digital twins.

As shown in my proposed Urban Digital Twin Taxonomy below, I propose that we classify these products first based on their Main Functionality (the Use Case), then based on their Technology Platform. I highlight some of main products within the different categories and their product scope.

Next, I detail the different types of twins and offer some brief strengths and weaknesses for each type. This taxonomy could apply to other industries such as architecture or manufacturing, but it is specifically applied to cities and urban development projects.

The main functionalities can be grouped by:

• Modelling Twin

• Computational Twin

• Scenario Twin

• Operational Twin

• Experiential Twin

The technology platforms can be grouped by:

• Computer Aided Design (CAD)

• Web GIS

• Geographic Information System (GIS)

• Gaming

BIM is not included since it is limited to building scale objects and does not have any data model for the broad spectrum of urban systems.

Please let me know what you think! Did I miss anything?

■ www.linkedin.com/in/darrelronald

Modelling Twin

This is the most common type of urban digital twin because it provides basic functionality and workflows common to traditional CAD software. These can be based on either CAD technology (running mostly on the desktop computers) or Web GIS technology.

These products support mostly manual design modelling with automations in the background. In some cases parametric inputs and form generation algorithms are exposed so that it is more interactive.

Strengths

CAD

• High accuracy modelling and data.

• Common design process and easy to learn.

• Very powerful general purpose software readily available.

Web GIS

• Can integrate external geospatial data layers.

• Common design process and easy to learn.

• Easier for multiple users to view the twin (but does not mean collaborate in real time).

Scenario Twin

The majority of these urban scenario twins are based upon GIS or Web GIS technology. Due to their GIS origins and data sources, this is especially 2D geometry and analysis, with some products working on better 3D integration.

Due to their GIS origins they tend to implement well known geospatial tools and analysis to the product.

Strengths

• It can allow for diverse testing of development scenarios, but this depends on the product itself.

• Potential to integrate many geospatial data layers.

• Web GIS — common design process and easy to learn.

• Web GIS — easier for multiple users to view the twin (but does not mean collaborate in real time).

Weaknesses

• Limited to a specific geographical region (always).

• Limited to geospatial data sources.

Weaknesses

CAD

• More difficult to integrate external geospatial data layers.

• Mostly limited to desktop modelling.

• Real-time collaboration is difficult.

Web GIS

• Low data accuracy for both the model and external data layers.

• Mostly limited to web-based modelling and requires continued internet connection to run.

• Risk of high (or very high) operational costs.

• Limited geometric detail and accuracy.

• Web GIS — risk of high (or very high) operational costs.

• It is well known and documented that urban development scenarios are far more complex than any simulation can offer, so there is an illusion of control, accuracy and intelligence that is very risky to decide urban policy on.