Low hanging fruit for mixed reality fabrication

The ability to view 3D models precisely in space creates obvious opportunities for mixed reality to improve tasks like set out or clash detection during construction of conventional buildings. However as conventional buildings are typically optimized for construction from simple 2D elements, standardised joints and minimal skilled labour, most tasks can be completed from simple 2D drawings and manual measurements and situations in which mixed reality can radically affect construction time, cost and risk are rare. The real potential of mixed reality fabrication to impact the built environment will remain largely unrealized until its affordances can be anticipated earlier in the design process.

Mixed reality affords certain novel fabrication tasks and design systems to be realised in comparable time frames and cost to conventional construction, while facilitating simpler documentation requirements, more formal variation, greater adaptability, faster learning curves without increased risk of failure and so on. Some approaches, together with examples and affordances are listed below in the hope of drawing attention to opportunities for design experimentation and improvement.

  1. Highly variable 2D pattern application
  2. 3D pattern application
  3. Stacked 2D patterns
  4. Mass-assembly of parts with discrete joints
  5. Flexible joint systems
  6. Pinned joint systems
  7. Continuous / amorphous material systems
  8. Fabrication directly from stock materials
  9. Approximate assembly with flexible materials
  10. Visualizing structural requirements to distribute low quality materials
  11. 3D tool orientation
  12. Subtractive forming / Silhouette carving
  13. Approximate sheet forming
  14. Fabrication of compound curves / splines
  15. Fabrication of compound bends / polylines
  16. Ad-hoc integration with existing conditions

1. Highly variable 2D pattern applications

Aesop Store, March Studio

Benefit: Speed, variation, design adaptability, visual quality control checks and reduced risk of human error.

Considerations: Reduced precision over large scales, precision vs time tradeoff at small scales.

Can be used to view contextual fabrication metadata along with the simple 2D pattern - for instance to show where parts are located along with orientation, extrusion height, colour etc. An example application like this would be March Studio’s aesop stores.

Can also be used as an adaptable alternative to lasercutting if high precision is not required. As an example, each of the ~400 steel brackets in the Tallinn Pavilion required pre-drilled and tapped holes on bend segments that would connect to timber boards. Rather than lasercutting parts, printing drawings or producing measurement lists to locate hole centers, we used an interactive holographic model to step through 2D drawings of each part as they were needed and used these to locate drill holes. This reduced fabrication time and enabled us to change the design of any part at any time.

2. 3D pattern applications

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Stitch, Rosie Gunzburg

Benefit: Simple documentation, speed, visual quality checks and reduced risk of human error

Considerations: Requires a scan of a physical object, and/or precise alignment of the digital pattern with the object to be traced. Low precision over large scale and error introduced from challenges of judging hologram depth.

Ordinarily applying patterns to 3D objects requires projection mapping or unrolling of the drawing to be applied. Using a 3D hologram aligned with the object to trace is a far simpler process and so reduces both fabrication time and documentation requirements.

3. Stacked patterns

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Royal Hobart Hospital Holographic Instructions, Fologram

Benefit: Simple documentation, speed, visual quality checks and reduced risk of human error

Considerations: Reduced precision over large scales, precision vs time tradeoff at small scales.

Eliminates the cost of design variation (e.g. brick types or locations) by removing the need for time consuming measurements and template setout. Because brickwork is completed in courses, holographic information can remain 2D (at different heights) eliminating the fabrication challenge of correctly judging hologram depth.

4. Mass assembly of parts with discrete 3D joints

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UTAS Workshop, Fologram

Benefit: Simple documentation, simple visual quality control checks, parallel construction

Considerations: Benefits need to outweigh overheads of setting up and using mixed reality

In design systems where parts are precisely pre-fabricated and can only join in explicit locations (e.g. lego blocks), mixed reality creates opportunities to complete fabrication in parallel by more efficiently distributing fabrication tasks, tracking fabrication completion, and providing clear visual references to design intent to minimize fabrication mistakes. These benefits will only be realizable for designs that are either difficult to read on screen (3D joints, mirror conditions, linework etc) or too detailed to efficiently produce 2D documentation for.

5. Universal Joints

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Pelican Studios

Benefit: Speed, precision, reduced documentation / detail complexity, adaptability, reduced waste, reduced chance of accumulative error,

Considerations: Challenges judging depth of near holograms. Joint system needs to be tolerant of small errors in joint positions.

Universal joints (e.g. ball and socket joints) with one or more degrees of freedom are well suited to mixed reality because a 3D hologram can be used to show both the local conditions of the correct joint geometry as well as the global conditions of the assembled product, enabling fabricators to make small adaptations to joints during construction to eliminate accumulative errors.

6. Pinned joint systems

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Inferno Redux, Artillion Studio

Benefit: Speed, precision, reduced documentation / detail complexity, adaptability, reduced waste, reduced chance of accumulative error,

Considerations: Challenges judging depth of near holograms, design language can appear arbitrary

Holographic models can also be used to effectively eliminate the need for considered joints in a design and leave these up to the fabricator. A good example of this is using tack welding joints between arbitrarily positioned elements.

7. Continuous / Amorphous material systems


Flow Morph, UCL Bartlett

Benefit: Speed, precision, reduced documentation / detail complexity, adaptability, reduced waste, reduced chance of accumulative error,

Considerations: Challenges judging depth of near holograms, imprecision of fluid materials requires very wide tolerance designs

Holographic models can also be used in additive fabrication processes as a kind of analogue 3D-printing. Adding human dexterity to amorphous processes of material deposition enables some very creative and unusual approaches to form making, with a good example of this being the FlowMorph project from Soomeen Hahm’s students at the Bartlett UCL.

8. Fabrication directly from stock materials

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Fologram

Benefit: Design adaptability and reduced documentation / detail complexity, reduced waste, reduced chance of accumulative error

Considerations: Stock material limits design language. Reduced precision at larger scales.

The approach here is to use a holographic model to orient stock material which is then tacked in place and cut to length (again using the hologram). Eliminates the need for prefabricated and labelled parts and thereby maximizes design adaptability during fabrication. As a result this approach lends itself to a very fast turnaround from design sketch to fabrication process.

9. Approximate assembly from flexible materials

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ARgan, Kristof Krolla & Garvin Goepel

Benefit: Reduced learning curve, reduced risk of accumulative error, visual quality checks, a lot of flexibility in design documentation (anything from just showing a surface model of the finished result through to physically simulating expected behaviour of each part)

Considerations: Can be extremely difficult to maintain alignment between hologram (which is static) and physical material (which is moving / flexing / sagging).

Enables fabrication of curved designs from bending active materials and reduced requirement for jigs and formwork. Requires significant skill to maintain alignment between static holographic model and dynamic, moving material and generally also requires a wide-tolerance approach to design (prioritizing meeting design intent and reduced fabrication time over precision).

10. Visualizing structural requirements to distribute low quality materials

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Fologram

Benefit: Anticipate material strains and minimize faults, reuse waste / low cost materials, visual quality control checks and improved training

Considerations: Reduced precision over large scales, precision vs time tradeoff at small scales.

As an example, around 60% of the timber in the Tallin Pavilion is low quality (knotted and flat sawn) and would be very difficult to bend into even lose radii. By using a hologram to visualize how each board would bend along its length we were able to distribute material such that it never exceeded bending limitations and utilize low quality material without risk of part failure or breakage.

11. 3D tool orientation

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Bench, Aki Hamada and Eri Sumitomo

Benefit: Speed, low cost, reduced need for documentation and automation, enables arbitrary joint designs

Considerations: Very low precision compared to CNC approaches due to challenges of judging depth with nearby holograms and also physically working with hand tools. Requires a wide tolerance design approach

An excellent example of using a holographic model to guide the orientation of a tool in 3D space is by Aki Hamada Architects and Eri Sumitomo who used this approach to drill dowelled joints between timber logs. By aligning the holographic model showing the correct tool location with the physical tool a fabricator can make arbitrary cuts / holes / notches etc in 3D space. This approach can be improved by placing a marker on the physical tool to provide some visual feedback to the fabricator as to when the tool is in the correct orientation.

12. Subtractive forming / Carving silhouettes

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Fologram

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Secret Whispers, Kristof Krolla & Garvin Goepel

Benefit: low cost, clear visual feedback on quality control

Considerations: Very low precision compared to CNC approaches due to challenges of judging depth with nearby holograms and also physically working with hand tools. Requires a wide tolerance design approach

It is possible to reduce the risk of accumulative errors and the complexity in general of subtractive forming processes by using a holographic guide showing the silhouette of a design from the fabricators tracked vantage point. This approach can be further improved by tracking cutting tools to provide feedback to fabricators, though the imprecision of marker tracking together with a requirement for significant craft skill still serve as barriers to achieving precise results.

13. Approximate sheet forming

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USC Workshop, Fologram

Benefit: Speed, low cost

Considerations: Very low precision compared to CNC approaches due to low resolution of marker grid. Requires a wide tolerance design approach

Sheet materials can be arbitrarily formed (e.g. by bending and reinforcing or heat forming etc) using a holographic model as a guide to the desired end state. This is typically extremely difficult to achieve without visual feedback due to challenges judging holographic depth, and so one solution is to directly stencil the material being formed with markers in order to track the change in the sheets shape over time. We’ve barely experimented with this idea, but think it has some promise especially at much larger scales than pictured above.

14. 3D splines / Compound curves

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Fologram & Agency of Sculpture

Benefit: Reduced training time / expertise requirements, speed, precision, low cost, design adaptability, visual check of quality

Considerations: Reduced precision at larger scale, difficulty of making changes to parts during fabrication means that designs should be tolerant of some error

Fabricating 3D splines is very difficult to do from 2D projections and so these geometries are typically rationalized into simple polyarcs. It is possible to fabricate arbitrary splines using 3D holographic templates as guides in combination with various forming techniques (heat bending, cold rolling etc), and the holographic models serve as an excellent visual check on part precision / tolerances. Holographic models can also be used to efficiently set out ad-hoc formwork to assist with forming 3D splines (e.g. with steam bending timber boards).This in turn reduces the learning curve associated with these otherwise complex fabrication tasks.

15. 3D polylines / Compound bends

Benefit: Reduced training time / expertise requirements, speed, precision, low cost, design adaptability, visual check of quality, reduced chance of accumulative error

Considerations: While a hologram of the overall part helps avoid accumulative error, small errors in individual bends are still frequent resulting in a need for wide tolerance design.

Holographic models can help fabricators position parts in 2D bar benders to fabricate 3D polylines from compound bend angles (a bend in two planes). Compound bend angles are very time consuming to fabricate otherwise as they require multiple measurements or templates for every individual bend. By replacing these with a simple visual check it becomes much quicker to form compound bends, without introducing risks of accumulative error.

16. Ad-hoc fit with existing conditions


ACADIA 2018 Workshop, Fologram

Benefit: adaptability, reduced chance of clashes and incorrect fit

Considerations: low precision of marker tracking and hololens scan requires highly adaptable joint and design systems.

It is possible to invent hybrid approaches to fabrication that combine ad-hoc hand craft with digital precision by utilizing tracked markers or the hololens spatial mesh as input to parametric models that create precisely fitting parts. We explored this approach in our ACADIA 2018 workshop, and there are plenty of opportunities to extend this beyond the material (timber stock), joints (compound cuts + but joints), structure (framing), context (blank slate) etc.

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