Rendering: Demetris Shammas
Fragments of the 3D printed grotto

Composition: Design by Algorithm

In computational design, the architect no longer develops form by pen on paper or by mouse in CAD program, but instead defines procedures to generate form. Shifting the design process onto this abstract level has a dramatic impact: Forms can be designed with a complexity and richness that would be impossible to draw by hand. Now these complex forms can be brought out of the computer using additive manufacturing. Bits and bytes can be rendered directly into reality.

The combination of computational design and additive manufacturing can lead to a non-standardized, highly differentiated and spatially complex architecture that is defined at the scale of millimeters. In the Digital Grotesque project, every detail of the architecture is generated through customized algorithms, without any manual intervention. A simple input form is recursively refined and enriched, culminating in a geometric mesh of 260 million individually specified facets. This single process generates many scales of architecture, from the overall form with its broad curvature, to local surface development, down to minute textures.

At a basic level, the algorithm used to generate the Digital Grotesque room functions by gradually refining and enriching a simple input form. The surfaces of a form are divided into smaller surfaces, and these in turn are divided again and again. Changes to one surface propagate down to its children. By altering the division ratios, one can control the geometry of the form.

Using this simple process, one can create astoundingly complex geometries with only a few subdivision steps. By changing the division ratios, one can also generate a surprising variety of forms. The process remains entirely the same; only the division parameters are altered.

This example sequence shows variants of square that is being successively divided into smaller squares, while the division ratio are altered. While this example is two-dimensional, the same principle also works for three-dimensional forms.

Subdivision of a square

While computational geometry in architecture is often used to create volumes with smooth, minimal surfaces, in Digital Grotesque the design goal is exactly the opposite. We sought to achieve maximal articulation of surfaces to create volumetric depth. Light is reflected in countless directions and the boundaries of the architecture are spatially diffuse.

The subdivision process that is used to articulate the form produces information at multiple scales. The closer one gets to the form, the more features one discovers. Such a hierarchical differentiation can also be found in classic architecture. Yet unlike traditional architectural design processes, here a single process is used both to sculpt the overall form, and to create the minute surface details. This procedural articulation can be used to create features that exceed the threshold of immediate haptic and visual perception.

Information at the threshold of perception

New Fabrication Methods Require New Design Tools

Today, we can fabricate anything. Digital fabrication now functions at both the micro and macro scales, combining multiple materials, and using different materialization processes. Complexity and customization are no longer impediments in design.

While we can fabricate anything, design arguably appears confined our instruments of design: we can only design what we can directly represent. If one looks at 3D printed artefacts, there is oftentimes discrepancy between the magic of digital fabrication and the conventionalism of the printed objects.

What is needed is a new type of design instrument. We need tools for search and exploration, rather than simply control and execution. We require tools that go beyond the fulfillment or optimization of simple functional requirements, and that allow us investigate and advance more ambiguous factors of the design: soft criteria.


Digital Grotesque is the first human-scale immersive space entirely constructed out of 3D printed sandstone. The design consists of two individual halves (Aediculae) that form a volume – the grotto. While on the outside the grotto presents itself as a flat cubical volume, on the inside a complex geometry, consisting of millions of individual facets that awaits the visitor.

The grotto was purely designed and detailed through customized algorithms. It is printed at a resolution of a tenth of a millimeter to dimensions of a 3.2-meter high, 16 square meter large room.

As it is the first architectural high-resolution 3D Print, innovative construction details had to be invented. In order to facilitate the transportation and the assembly of the massive construction, a modular system of individual, prefabricated sandstone bricks with specific details is developed. 3D-Printing as fabrication process allows the planning of three-dimensional details in an unknown consistency and precision, and offer the possibility to develop customized constructions systems.

For Digital Grotesque, we developed an innovative construction system based on a discrete assembly of smart bricks. These 3D printed bricks can have surface formations at a previously unseen level of detail. Internally, they are partially hollow with a sub-interior structure to reduce material according to force flow. The bricks have integrated labels as well as alignment and lifting details that enable a mortar-free assembly. All of these features are directly printed into the brick, without the need for any secondary material or processes.

In Digital Grotesque, these self-supporting bricks are dimensioned to fit onto standard Euro pallets [120x80cm] for easy transport. The material thickness of the bricks varies with their position within the structure and with the loads they need to sustain.

Schematic of individual bricks

The geometry of the grottos consist of 260 million and 1.35 billion individual faces respectively. This large amount of data cannot be adequately processed by existing CAD Software. Customized algorithms were therefore developed to calculate the construction details and to convert the form into printable data.

The articulated mesh is a self-intersecting surface that does not enclose a volume as it is not a differentiable, orientable manifold. In order to extract a volume with a uniquely definied inside and outside from this geometry, a strategy analog to casting is implemented: The folded surface is filled with water. Every part that stays dry in this simulation is counted as the inside of the wall construction. As a result, a clean volume emerges.

To calculate this volumetrization and to insert construction details, the entire mesh is voxelized at resolution of 1mm (0.8mm for grotto 2), leading to 30 billion spatial data points. Such an enormous amount of information cannot be processed as a single entity in the computer: the geometry is loaded only where needed, streamed layer per layer.

Information at the threshold of perception