A 3D tactile model for architecture: all the secrets

This post is also available in: Italiano

The scale model is one of the most established and traditional tools of architectural communication. Its innate three-dimensionality can describe an artefact in detail, addressing a very heterogeneous public, without requiring any deep comprehension of the architectural drawings.

While ancient models were mainly made of wood, today we have a wide range of solutions available, both as regards the techniques and the materials used to produce the models, at any representation scale: we can now achieve levels of detail that were unimaginable just a few years ago.

The physicality of the scale model opens possibilities for tactile utilisation, allowing blind people to appreciate all the details of a specific architecture. To understand the features of a 3D tactile model in a practical way, let’s try to highlight the main similarities and differences compared to a traditional model, made only for visual enjoyment.

What are the peculiarities of a 3D tactile model?

For the sake of clarity, an introduction is necessary: creating effective 3D tactile models is not a task for a neophyte. It requires adequate cross-disciplinary skills: knowing and managing the main modelling techniques, knowing how to read architecture and, based on this, identifying the most suitable solutions according to the budget available for a specific project.

An experienced modeller must be able to find a balance between at least three key factors.

The tactile model is always a scale model of architecture. Compared to the conventional model, the “cultural mission” of respecting the characteristics of the original work remains unchanged, in particular as regards the general proportions and the relation between all the parts. Though designed for the blind public, a 3D tactile model is in most cases suitable also for undifferentiated use.
Compared to the model designed for simple viewing, the tactile model must highlight the differences between the parts only resorting to physical contact. At the risk of stating the obvious, this consideration implies the need to reinterpret some parts of the model, differentiating them in geometry and/or in the choice of materials. It is fundamental to prepare a legend that is easy to understand while abiding as much as possible by the communication standards of blind people (Braille language, etc.).
The tactile model must be designed taking into account the inevitable stress that a visual model is not expected to endure, especially when protected by a display case. The points most stressed must be sized appropriately. The arrangement must facilitate access of blind people to the model, avoiding crowding that would hinder its utilisation, as well as increasing the risk of improper handling of the model.

It’s easy to understand how these aspects must be assessed case by case, depending on the architectures being reproduced and the customer’s display needs.

De Albertis Castle - Genova - tactile model — A scale model of D’Albertis Castle in Genoa – overview of the model, made of full-colour sandstone with 3D Systems technology (credit: Protocube Reply)

De Albertis Castle - Genova - tactile 3d model — A scale model of D’Albertis Castle in Genoa – the model offers a reading of the work at different scales, contextualising it at an urban and architectural level. The model is designed to be used by both the undifferentiated public (differences in colour) and blind people (differences in materials). The texts also feature a Braille version (credit: Protocube Reply)

How to make a 3D tactile model?

The process of designing and producing a 3D tactile model has many steps:

Data acquisition – as in the case of a conventional model, the first step is to review archive documentation, 3D scans or photogrammetric reconstructions of the architectural asset to be reproduced.
3D modelling – the creation of the digital model constitutes the crucial moment of its design, in which all the considerations made in the previous paragraph come into play. When making the model using predominantly 3D printing, all the parts need to be sized accordingly. In the case of large models made of several parts to be assembled, it is important to pay attention to the division of the parts, also with a view to optimising the quantity of material used during the printing process to reduce the costs of the project even in a significant way.
Prototyping – the revision process is subject to constant dialogue with the particular type of audience. The person who creates the model cannot receive the same feedback as a blind person, with whom they must communicate consistently to receive useful information for the effective finalisation of the project.
Production – From a technical point of view, a 3D tactile model is produced with a wide variety of techniques and materials. In relation to a traditional model, some additional care is needed: it is important to provide appropriate reinforcements for the smaller parts or parts for which greater stress is expected, by increasing the minimum cross-sections, using suitable metal pins, or joining more elements, whose connections are hidden by pieces inserted during the design phase.

The 3D modelling of a scale model requires a critical selection: all architectural details must be reproduced faithfully. For this purpose, the modeller needs to document well, using architectural drawings, images and scans of the real work. The image depicts a detail of the pavement of the Palatine Gates in Turin (scale 1:200, left) and of the entrance of the Gran Madre di Dio church, with details of the colonnade and the tympanum (scale 1:200, right) (credit: Protocube Reply)

A detail of the scale model of the Cathedral of Turin shows a phase of the assembly of the dome of the Chapel of the Holy Shroud, whose real counterpart was seriously damaged by a fire in 1997 and was recently reopened after a long and complex restoration. The expertise of those who create the model is fundamental when separating the whole into parts that must be easy to create and assemble during the final set-up (credit: Protocube Reply)

Palazzo Madama - Torino - tactile model — A 1:200 scale model of Palazzo Madama in Turin. The tactile 3D model features considerable differences in surface detail, making the medieval parts of the Castle of the Princes of Acaja easily recognisable over the baroque façade designed by Filippo Juvarra. The model is part of a series created for The Italian Union of the Blind and Partially Sighted, which includes, among other works, the Mole Antonelliana, the Gran Madre di Dio church, the Palatine Gates and the Cathedral complex (credit: Protocube Reply)

Is 3D printing the technical solution to the problem?

In most cases, a 3D tactile model is produced as a single piece or in a very limited series, a condition that makes the use of 3D printing favourable. Though the context is extremely favourable, it would be simplistic to limit the advantages of 3D printing to the production of a specific one-off model. Additive manufacturing assists the designer from the very first stages of design, allowing samples and prototypes to be created in-house, in no time, to be shared with the customer for revisions. 3D printing is also fundamental even after the model has been made.

The particular use envisaged for tactile products entails the need to provide for spare parts. In practice, in the case of serial elements (e.g. trees, fences, etc.), it is possible in the production phase to manufacture more elements than those strictly necessary for the assembly of the model, to have replacements available in case of breakage. Having the 3D digital model available also makes it possible, at any time, to reproduce any part of the model, and to carry out repairs even of complex parts in a very short time.

In spite of being flexible and congenial to this solution, 3D printing is by no means a prerogative for this kind of production, which admits many hybridisations. For some parts of the supporting bases, 3D-printed solutions are rarely used, preferring instead blocks of homogeneous material, milled at the points where the inserts go. Other parts can be made with laser cutting systems, others by modelling sheets of homogeneous material. There is no limit to creativity. Without prejudice to the project criteria and technologies functional to additive production, it is therefore advisable to use an artisanal approach in this case: another aspect that cannot be separated from expertise but constitutes the key element that makes the difference, especially when it comes to achieving the best value for money.

To view some examples of 3D tactile models, in addition to those mentioned in this article, we suggest reading the case studies of the National Cinema Museum of Turin and the Porta Pretoria in Aosta.

For a summary of the application potential of the scale model in architecture, we suggest reading the in-depth analysis The 3D model in architecture: Design, Marketing, Culture.