Publication: Christian Weichel, John Hardy, Jason Alexander, and Hans Gellersen. 2015. ReForm: Integrating Physical and Digital Design through Bidirectional Fabrication. In Proceedings of the 28th Annual ACM Symposium on User Interface Software & Technology (UIST '15). ACM, New York, NY, USA, 93-102. DOI: http://dx.doi.org/10.1145/2807442.2807451 Abstract: Digital fabrication machines such as 3D printers and laser-cutters allow users to produce physical objects based on virtual models. The creation process is currently unidirectional: once an object is fabricated it is separated from its originating virtual model. Consequently, users are tied into digital modeling tools, the virtual design must be completed before fabrication, and once fabricated, re-shaping the physical object no longer influences the digital model. To provide a more flexible design process that allows objects to iteratively evolve through both digital and physical input, we introduce bidirectional fabrication. To demonstrate the concept, we built ReForm, a system that integrates digital modeling with shape input, shape output, annotation for machine commands, and visual output. By continually synchronizing the physical object and digital model it supports object versioning to allow physical changes to be undone. Through application examples, we demonstrate the benefits of ReForm to the digital fabrication process.

1. ReForm: Integrating Physical and Digital
Design through Bidirectional Fabrication
ChristianWeichel
John Hardy
Jason Alexander
Hans Gellersen
Lancaster University, UK.

2. ReForm provides a more flexible design process
by combining physical and digital modeling.

4. The Concept
Bi-directional Fabrication
The Implementation
ReForm

5. +
Motivation
 The creation process is uni-directional: once an object is fabricated it
is separated from its virtual model.
• Ties users to virtual modeling tools.
• Virtual design must be completed
before fabrication.
• Re-shaping the physical object no
longer influences the digital model.
http://www.computerweekly.com/feature/How-3D-printing-impacts-manufacturing

6. +
Bidirectional Fabrication

7. +
Bidirectional Fabrication
Users can flexibly
move between
working on the
digital model and
physical object.

8. +
Bidirectional Fabrication: Advantages
 The right tool for the right job:
 Expressive manipulations using the physical object
 Precise/repetitive actions using digital tools
 Evolutionary Fabrication:
 Incremental addition/subtraction/modification of the object
 ‘On-the-fly’ validation and refinement of the style, size, and confirm each
element is fit-for-purpose.

9. +
Bidirectional Fabrication: Advantages
 PhysicalVersionTracking:
 Physical object is continually synchronised to the digital model, allowing
undo, redo, and version tracking in the physical world.

10. +
ReForm
 Additive and subtractive
fabrication system.
 Reusable polymer clay which
is extrudable, machinable, and
sculptable.
 Implements the bi-directional
fabrication concept.

11. +
Capabilities & Operations
• Additive and Subtractive
Fabrication
• 3D Scanning
• Augmented Reality Overlay
Capabilities

12. +
Capabilities & Operations
• Additive and Subtractive
Fabrication
• 3D Scanning
• Augmented Reality Overlay
Capabilities
• Synchronized Digital
and Physical models
• Physical Shaping
• Digital Modeling
• History andVersioning
Operations
Enable

13. +
Starting A Session
Digital Model
Physical
Object
Online Repository
CAD Model
Saved ReForm Session
Object in theWorld
Clay Model
Digital Model
D Scan3
Physical
Object
Fabricate

14. +
Physical Shaping
(A) User can mold objects with their hands
(B) Using tools
(C) Or with existing objects

15. +
Digital Modeling: Global Operations
(A) Global flatten
(B) Scaling the object

16. + Digital Modeling:
Selective Operations via Annotations
(A) Extruding an annotated patch
(B) Producing accurate holes
(C) Patterning model features

18. +
History andVersioning
(A) Modifications to the physical object
(B) Can be undone using the digital model
(A)
(B)

20. +
Implementation
(a) Jog wheel
(b) LMI HDI120 3D scanner
(c) Asus Xtion depth camera
(d) Heated clay extruder
(e) Milling spindle
(f) Build plate
(g) Projector and screen
(h) Air-guide
(i) ReForm Core.

21. +
Example Output Designs

22. +
Discussion
 What is the impact on the design process? How do we measure it?
 Does ReForm encourage different or better designs?
 How do we address the accuracy/time trade-off in physical creation?

23. +
Summary
 Bi-directional fabrication entangles digital and physical objects so
that updates to one always propagate to the other.
 ReForm implements this concept allowing us to demonstrate the
novel and flexible design process.

24. ReForm: Integrating Physical and Digital
Design through Bidirectional Fabrication
ChristianWeichel
John Hardy
Jason Alexander
Hans Gellersen
Lancaster University, UK.