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ReFabricator: Integrating EverydayObjects for Digital Fabrication
Suguru YamadaKeio UniversityEndou 5322, Fujisawa,Kanagawa, [email protected]
Masaki OgawaKeio UniversityEndou 5322, Fujisawa,Kanagawa, [email protected]
Hironao MorishigeKeio UniversityEndou 5322, Fujisawa,Kanagawa, [email protected]
Takuro YonezawaKeio UniversityEndou 5322, Fujisawa,Kanagawa, [email protected]
Hiroki NozakiKeio UniversityEndou 5322, Fujisawa,Kanagawa, [email protected]
Hideyuki TokudaKeio UniversityEndou 5322, Fujisawa,Kanagawa, [email protected]
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AbstractSince current digital fabrication relies on 3D printer verymuch, there are several concerns such as printing cost (i.e.,both financial and temporal cost) and sometimes too ho-mogeneous impression with plastic filament. To addressand solve the problem, we propose ReFabricator, a com-putational fabrication tool integrating everyday objects intodigital fabrication. ReFabrication is a concept of fabrica-tion, mixing the idea of Reuse and Digital Fabrication, whichaims to fabricate new functional shape with ready madeproducts, effectively utilizing its behavior. As a system pro-totype, we have implemented a design tool which enablesusers to gather up every day objects and reassemble themto another functional shape with taking advantages of bothanalog and digital fabrication. In particular, the system cal-culates the optimized positional relationship among objects,and generates joint objects to bond the objects together inorder to achieve a certain shape.
Author KeywordsComputational Design, Algorithmic Modeling, ComputerGraphics, Digital Fabrication, Bricolage, 3D printing
ACM Classification KeywordsD.2.2 [SOFTWARE ENGINEERING Design Tools and Tech-niques]: Computer-aided software engineering (CASE)
IntroductionPersonal Fabrication has been widely known due to thespread of digital fabrication technology such as free CADsoftware and open source 3D data. Although it is revital-izing public creativity, digital fabrication depends on sin-gle material such as plastic filament when using 3D printerwhich makes the output impression homogeneous. On theother hand, people have been creating products from thepast by reusing surrounding objects. Reused objects hasits unique value and warmth that digital minimum materialdoes not contain. However, combining surrounding objectsneed high expertise which restricts the potential of designfor the endusers. For example, it usually requires much try-and-error process to decide how to place and connect theeveryday objects to make target shape.
Figure 1: Prototype output image
Registration phase
Positioning phase Connecting pahse
Surrounding Object Target Object
ReFabricator
Positioning Joint
Output
Figure 2: Process Flow ofReFabrication
Having listed the pros and cons about both of digital andanalog fabrication, this paper presents a concept of mixingthe idea of reuse and digital fabrication process. We callthis ReFabrication(Reuse + Fabrication), a hybrid fabrica-tion style utilizing the unique behavior of everyday objectssuch as shape, texture, or structure by obtaining supportfrom CAD software. This aims to take in as many paramet-ric function of the material object as possible, in order tomaximize the variety of fabrication inputs. For example, ifwe can utilize textures and shapes of a material, we canoutput artistic piece such as collage art, and if we take instructures and durability, architecture can be created.
By ReFabrication, everyone could easily make collage artswhich would widen expression skill and enhance creativ-ity(e.g. making an interior from surrounding objects), andflexible fabrication could be done in polar environment likein outer-space and material-less developed countries. Asa system prototype, we have implemented ReFabricator, acomputational design tool supporting to fabricate with sur-
rounding objects. The prototype output is shown in Figure1. This is composed of everyday objects and 3D printedjoints which is generated automatically with ReFabricator.Our contribution is summarized in the following three points.
• Implementation of the prototype system of ReFabri-cation.
• Experimentation with the prototype system, tryingseveral elements and targets.
• Discussion based on the output result of the system,about the future possibilities of reuse fabrication.
Research Challenge and StepsReFabrication consists of three steps as it is shown be-low, with related works and the research challenge for eachstep. The process flow is shown in Figure 2.
Registration phase: First of all material should be registeredin order to be calculated. To compute optimal position of ev-eryday objects and joints, 3D data of the material should beconverted before construction. Recently, open source of 3Ddata is prospering including Thingiverse[1] , which is mak-ing acquisition of 3D data easy. In addition, 3D scanningtechnology has also advanced, like inexpensive scannerand making smart phones a scanner. These technologyhas been practically used in personal fabrication. Com-plex Construction has been designed easily when makingchairs and paper planes are reinforced by the support ofCPU[2][3].
Positioning phase: After registering the element(hereafterelement), we need to optimize the element to the suitableposition to achieve the function of the target(hereafter tar-get). An algorithm which automatically generates a 3D col-lage in CG space is developed by Ran[4], but since it isfocused on creating a collage in CG space, it is permitting
the data to be resized and overlapped which does not ac-count the physical limitations of space. Another algorithmdeveloped by Zhe[5] automatically generates a complex3D collage by constructing pre-designed materials, but itis difficult to apply with variety of objects in the surround-ings because the elements they are using are consciouslydesigned for construction.
Connecting phase: Connecting phase in ReFabrication re-quires to connect many everyday objects easily. In addition,the connected objects should be also disconnected easilyfor reusing them in another purposes. In order to obtain thestructure after optimization, elements should be connectedtogether and be statically solid. AutoConnect, developed byYuki[6] arranges a joint which connects two surrounded ob-jects automatically. However since it is assuming to connectonly two objects, the algorithm in generating multiple jointsare restricted.
As it is shown above, our research is focused on the phaseof Positioning and Connecting. The technical requirementsin these phases are partially fulfilled with related works,however, there are still problems to be solved for realizingReFabrication concept such as how can we place and con-nect multiple ’real’ everyday objects in real space.
VeVT / < D
Ve/ > D
Element Object
Get Bouding Box
...
Packing Target Boundinfg Box
with Element Bounding Box.
Target Object
∩e
VT∩e
VT∩e
Figure 3: Element PositioningAlgorithm
PrototypeReferring to the phase written above, we developed a pro-totype system for ReFabrication. When the user inputs sev-eral surrounding objects, the system outputs simulated po-sition data and connectable joints to fulfill previously regis-tered shape. We will describe the design and implementa-tion of each module of ReFabricator.
DesignPositioning elements to express the shape of the target:We define the target is well expressed when the packing
ratio of the element is maximized. We adopted the bin-packing algorithm developed by Crainic [7] and newly-devised their module to a more accurate one. In detail,we will extract the bounding box of each element and packthem into the bounding box of the target data. After the pro-cess, interacted ratio of each element and the target wouldbe calculated, and according to the fixed threshold, unnec-essary element will be sifted.
Connecting the shape in real space by using joints: Jointsare aimed to minimize the coverage of the element andmeet the minimum requirement of grip power, which is topreserve the shape and to repel gravity. In order to hold theelements in the positioned place in the real space, we gen-erate two component to connect elements together. Firstlythe system creates a holder to grip each element and sec-ondly places a snap to connect each holder. Both holderand snap is placed dynamically according to the positionalrelations of the element and united by the software and willbe finally printed by 3D printer.
ImplementationElement placement module: Using an algorithmic modelingplugin Grasshopper with CAD software rhinoceros[8][9], thesystem packs the element using a bin-packing algorithm[7].As it is shown in Figure 3, we first pack the element into thebounding box of the target using the bin-packing algorithmdeveloped by Crainic [7]. This considers the space to gen-erate joints, so there is a certain margin created betweenthe objects. After packing the joints, elements intersectedwith the target is once again evaluated and sieved by theratio of the volume intersected. the threshold of the ratio isset to 0.4 for the test output.
Joint generation module: In order to connect the elementstogether, we first developed a lookup module which createsa dictionary of the positional relation as shown in Figure 4 ).
The lookup module stretches a line to 6 directions along thex-y-z axis and see whether it intersects with another ele-ment. It entries the id of the element which is adjacent, andthe direction is also archived. After getting hold of the wholerelationship , from the center point of the element, preregis-tered snaps will be placed in each holder. Snaps are placedat the intersected point of the search line and the boundingbox of the element. If there is a certain distance from theactual element, the software automatically generates a rodto hold the snap from the element body.
Conclusion and Future WorkIn this paper, we have presented a fabrication concept ofmixing the idea of reusing and digital fabrication, and imple-mented a prototype system of ReFabrication, ReFabricator.The system gathers up everyday objects and form to differ-ent shape of an object. There are future works expected inReFabrication.
Functionality of the outputShaping is the most primitive and important function of fab-rication, but we want to make our output more functionalother than fulfilling the shape, such as controlling the tex-ture and strength of the structure or the color. It will bemore realistic to support in polar countries like develop-ing country. And further steps can be considered such asmaking things move with reused objects.
G:Center of gravity
x
y
z
Element0
x+ : 1y+ : Nonez+ : Nonex- : Noney- : Nonez- : None
...
Dictionary
Element1
x+ : Noney+ : Nonez+ : Nonex- : 0y- : Nonez- : None
Element2
G
x+ : 3y+ : 7z+ : Nonex- : 1y- : Nonez- : None
Figure 4: Joint GeneratingAlgorithm and Joints generated inreal space
Hybrid fabricationIn the prototype system, we have focused on reassemblingeveryday objects and we used the 3D printed parts as asimple joint. However, this is limiting the fine quality of dig-ital fabrication. Since we are aiming to mix the two fabrica-tion style, better algorithm to blend the 3D printed data isneeded.
AcknowledgementThe part of this research was supported by National In-stitute of Information and Communications Technology(NICT).
References[1] Makerbot. Thingiverse. "https://www.thingiverse.com"[2] Saul, Greg, et al. "SketchChair: an all-in-one chair
design system for end users." Proceedings of thefifth international conference on Tangible, embedded,and embodied interaction. ACM, 2011.
[3] Umetani, Nobuyuki, et al. "Pteromys: interactive de-sign and optimization of free-formed free-flight modelairplanes." ACM Transactions on Graphics (TOG)33.4 (2014): 65.
[4] Gal, Ran, et al. "3D collage: expressive non-realisticmodeling." Proceedings of the 5th international sym-posium on Non-photorealistic animation and render-ing. ACM, 2007.
[5] Huang, Zhe, et al. "Structured Mechanical Collage."IEEE Transactions on Visualization and ComputerGraphics 7.20 (2014): 1076-1082.
[6] Koyama, Yuki, et al. "AutoConnect: computationaldesign of 3D-printable connectors." ACM Transac-tions on Graphics (TOG) 34.6 (2015): 231.
[7] Crainic, Teodor Gabriel, Guido Perboli, and RobertoTadei. "Extreme point-based heuristics for three-dimensional bin packing." Informs Journal on com-puting 20.3 (2008): 368-384.
[8] Rhinocerous. "http://www.rhino3d.co.jp/"[9] Grasshopper. "http://www.grasshopper3d.co.jp/"
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