Herewith I present a new interaction technique for curve sketching in 3D which integrates the two tasks of creating and editing into one paradigm: the 3D eraser pen. The eraser pen allows drawing and deleting curves in 3D without mode switching just by changing the direction of the hand movement. In that way we have combined the creation and deletion process, rewriting the pencil and rubber metaphor in just one tool. The aim is to support the user to create the intended shape from the beginning. While the user is drawing a curve and recognizes that the shape does not conform to his or her intention, he or she can move back, erase a part of what was just created and move forward to create a curve piece that better fits to the desired shape. As a proof-of-concept we have developed our concept in a semi-immersive virtual environment for curve sketching in free space.

1. R. De Amicis, F. Bruno,
A. Stork, M. L. Luchi
GRIS, TU Darmstadt
Fraunhofer-IGD, Darmstadt
Università della Calabria
The Eraser Pen:The Eraser Pen: A New Interaction Paradigm forA New Interaction Paradigm for
Curve Sketching in 3DCurve Sketching in 3D

2. The Eraser Pen:
A New Interaction Paradigm for Curve Sketching in 3D
2
R. De Amicis,
F. Bruno,
A. Stork, M. L.
IntroductionIntroduction
Shape design using intuitive 3D interaction
techniques for free-form modeling increases
its contribution to...
• ...visual appeal
• ...ergonomic performance
• ...a product’s commercial competitiveness
through product differentiation

3. The Eraser Pen:
A New Interaction Paradigm for Curve Sketching in 3D
3
R. De Amicis,
F. Bruno,
A. Stork, M. L.
Current Practice and ObstaclesCurrent Practice and Obstacles
• Current CAD tools do not serve well shape design
• Can not handle quick sketching concepts.
• Serious difficulties are encountered in the styling
phase of the design process
• As a result, designers prefer to use manual
sketching tools

4. The Eraser Pen:
A New Interaction Paradigm for Curve Sketching in 3D
4
R. De Amicis,
F. Bruno,
A. Stork, M. L.
Current use of VR and AR within the Design ProcessCurrent use of VR and AR within the Design Process
Virtual Validation Process
CAS model
Virtual reality tools
CIM
CAPE
DMU
Structural analysis
CFD, NVH
Safety analysis
STYLING
ENGINEERING
MANUFACTURING



• Anticipating decisions and analysis
• Realistic digital display

5. The Eraser Pen:
A New Interaction Paradigm for Curve Sketching in 3D
5
R. De Amicis,
F. Bruno,
A. Stork, M. L.
Workflow for Aesthetic DesignWorkflow for Aesthetic Design
Classic Workflow
New Workflow
Optimized for
Aesthetic Design

6. The Eraser Pen:
A New Interaction Paradigm for Curve Sketching in 3D
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R. De Amicis,
F. Bruno,
A. Stork, M. L.
Related WorkRelated Work
• 3-Draw: A tool for designing 3D shapes. E. Sachs, et. al.
No visual correspondence
• Ext. SKETCH by Forsberg, Zeleznik et. al.
Imprecise sketching in 2D& 3D
• An Interface for Sketching 3D Curves, J.M. Cohen, et. al.
Curves and shadows can be ‘overdrawn’ to change theirshape.
• Free-Form Surface Design in a Virtual Environment, C.-C. P. Chu et. al
Indirect and distant interaction with a ray
• Surface Drawing, Schroeder et al.
Drawing polygonal structures in 3Dat VT using a glove

7. The Eraser Pen:
A New Interaction Paradigm for Curve Sketching in 3D
8
R. De Amicis,
F. Bruno,
A. Stork, M. L.
The BackgroundThe Background
The usercan:
• create 2D primitives,
• generate 3D primitives,
• sketch curves and surfaces
• perform Boolean operations,
• sweep faces,
• access the history of an object:
– to change it partially or
– to copy primitives,
• delete objects.

8. The Eraser Pen:
A New Interaction Paradigm for Curve Sketching in 3D
9
R. De Amicis,
F. Bruno,
A. Stork, M. L.
The IdeaThe Idea
Define a new interaction technique for aiding the sketching of polylines,
curves and surfaces.

9. The Eraser Pen:
A New Interaction Paradigm for Curve Sketching in 3D
10
R. De Amicis,
F. Bruno,
A. Stork, M. L.
The ImplementationThe Implementation
P
5
P
1
P
2
P
4
P
3
X
Y
Z
α
P
5
P
4
P
3
P
0
if (α > αmax)
draw
else
erase

10. The Eraser Pen:
A New Interaction Paradigm for Curve Sketching in 3D
11
R. De Amicis,
F. Bruno,
A. Stork, M. L.
Extruded curve!!
Change!!
The Eraser PenThe Eraser Pen
Generation of an extruded
surface
• First sketch
• The red spot highlights the
part that is redone
• Surface by curve extrusion.
combines the creation and deletion process, rewriting
the rubber and pencil metaphor in just one tool.

11. The Eraser Pen:
A New Interaction Paradigm for Curve Sketching in 3D
12
R. De Amicis,
F. Bruno,
A. Stork, M. L.
The Erase PenThe Erase Penconcept applied to model a skin surface

12. The Eraser Pen:
A New Interaction Paradigm for Curve Sketching in 3D
13
R. De Amicis,
F. Bruno,
A. Stork, M. L.
The Erase Pen ..a videoThe Erase Pen ..a video

13. The Eraser Pen:
A New Interaction Paradigm for Curve Sketching in 3D
14
R. De Amicis,
F. Bruno,
A. Stork, M. L.
The Erase Pen ..a videoThe Erase Pen ..a video

14. The Eraser Pen:
A New Interaction Paradigm for Curve Sketching in 3D
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R. De Amicis,
F. Bruno,
A. Stork, M. L.
Sketching free-formsurfaces in Mixed Realities
Engineering applicationsEngineering applications

15. The Eraser Pen:
A New Interaction Paradigm for Curve Sketching in 3D
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R. De Amicis,
F. Bruno,
A. Stork, M. L.
IGD-Darmstadt
Univ. of Technology-Darmstadt
ZGDV-Darmstadt CAPCom business & solutions -Darmstadt IGD-Frankfurt Univ. of Frankfurt
IGD-Rostock
Univ. of Rostock
ZGDV-Rostock
Ctr. for Research in Computer Graphics-Providence
Brown Univ.- Providence
Rhode Island School of Design-
Providence
Univ. do Minho- Azurem Centro de Computacao Grafica Univ. of Technology-Nayang Ctr. for Advanced Media Technology- Nayang
Univ. of Technology-Vienna
Thank you !Thank you !