Teddy: A Sketching Teddy: A Sketching Interface for 3D Interface for 3D Freeform DesignFreeform Design

Takeo IgarashiUniversity of Tokyo

Satoshi Matsuoka, Hidehiko TanakaTokyo Institute of Technology

SIGGRAPH 1999SIGGRAPH 1999

ListList

1. Abstract

2. Introduction

3. Related Work

4. User Interface

5. Modeling Operations

6. Algorithm

7. Implementation

8. User Experience

9. Future Work

1. Overview

2. Creating a New Object

3. Painting and Erasing on the Surface

4. Extrusion

5. Cutting

6. Smoothing

7. Transformation

1. Creating a New Object

2. Painting on the Surface

3. Extrusion

4. Cutting

5. Smoothing

Abstract *Abstract *

Sketching Interface for 3D Freeform Design Sketching interface for quickly and easily designing

freeform models

User draws 2D freeform strokes interactively

System constructs 3D polygonal surface automatically

System supports several modeling operations

• Inflating the region surrounded by the silhouette

Abstract **Abstract **

Teddy Prototype system Java program Mesh construction

is done in real-time

User Study (for first-user) Mastering the operations : 10 minutes Constructing interesting 3D models : minutes

1. Introduction *1. Introduction *

Creating Freeform Surfaces is difficult & tedious

SKETCH This paper extends ideas of SKETCH

Using Freeform strokes as expressive design tool User draw 2D freeform strokes interactively

System constructs a 3D polygon surface models based on the strokes

Editing operations by strokes

Resulting models have a hand-crafted feel

MoviesMovies

SKETCH: An interface for SKETCH: An interface for sketching 3D scenessketching 3D scenes

Modeling 3D Object by Sketch Interface Legends of strokes

CSG subtraction

1. Introduction **1. Introduction **

Paper Sketch Interface Algorithms for constructing 3D shapes from 2D strokes Implementation of our prototype system, Teddy

Geometric representation Standard polygonal mesh

Interface can be used to other representation Volumes or metaballs metaball

1. Introduction ***1. Introduction ***

Design Goal of Teddy Construction of approximate models

Not for careful editing of precise model

Interactive Real-time pen-and-ink rendering

Java on mid-range PC

1. Introduction ****1. Introduction ****

Obvious Application of Teddy Design of 3D models for character animation

Rapid prototyping in the early stages of design

Educational/recreational use for non-professionals and children

Real-time communication assistance on pen-based system

Figure 2:Painted models created using Teddy and painted using a commercial texture-map editor

Applications Applications

PC package MagicalSketch 2

Gamecube game Playstation2 game

                           

                              

2. Related Work *2. Related Work *

Geometric Modeling Typical procedure

- Start with a simple primitives

• Successive transformation

• Combination of multiple primitives

Transformation Techniques

- User create various precise, smooth models interactively

• Deformation [15] Free-form deformations with lattices of arbitrary topology

[23] Wires: a geometric deformation technique

• Shape manipulation [8] Visual interfaces for solids modeling

Construct complex model

Free-form deformations with Free-form deformations with lattices of arbitrary topologylattices of arbitrary topology

R. MacCracken and K.I. Joy. SIGGRAPH 96

Generalize Previous FFD Lattices of Arbitrary Topology Use Catmull-Clark subdivision

Wires: a geometric Wires: a geometric deformation techniquedeformation technique

K. Singh and E. Fiume SIGGRAPH 98

Wire curve is shape’s deformable features

2. Related Work **2. Related Work **

Implicit Surfaces ( Skeleton Models ) User specifies the skeleton of model

System construct smooth, natural-looking surfaces

[3] Interactive techniques for implicit modeling

[18] Polygon inflation for animated models: a method for the extrusion of arbitrary polygon meshes.

Surface inflation method [17] Object modeling by distribution function and a method of

image generation

Interactive techniques for Interactive techniques for implicit modelingimplicit modeling

J. Bloomenthal and B. Wyvill 1990 Symposium on Interactive 3D Graphics

User control its skeleton,system compute correspondingimplicit surface automatically

2. Related Work ***2. Related Work ***

This paper User specify the silhouette of shape instead of skeleton

Inspired by previous sketch-based modeling system Inferring 3D models from freehand sketches and constraints

SKETCH: An interface for sketching 3D scenes

Interpret user’s stroke and construct 3D rectilinear model

Goal of this paper Interface for designing rounded freeform models

2. Related Work ****2. Related Work ****

Inflation of a 2D drawing Shading in Two Dimensions

3D surface editing based on 2D painting 3D Paint Target is 2D array with associated height values Rather than 3D pol

ygon

Using 3D Input/Output Devices The Holosketch VR sketching system.

3D Paint3D Paint L. Williams 1990 Symposium on Interactive 3D Graphics

Extend Drawing, painting metaphor to 3rd dimensions

Surface is Height Value of 2D Arrays

2. Related Work ****2. Related Work ****

Freeform Strokes for 2D Application Specifying gestural command

Ambiguous intentions: A paperlike interface for creative design Interactive sketching for the early stages of user interface design

Specifying 2D curve A mark-based interaction paradigm for free-hand drawing

• Editing curve by sketching

Merits• Find the best matching arcs or splines automatically

• Freeing the user from explicit control of underlying parameter

Interactive Sketching for the Early Interactive Sketching for the Early Stages of User Interface Design Stages of User Interface Design

J.A. Landay and B.A. Myers. 1995 CHI

SILK Interface designers sketch the interface system produces application based on sketch automatically

2. Related Work *****2. Related Work *****

Volumetric representation Volume sculpting Sculpting: an interactive volumetric modeling technique Useful for designing topologically complicated shapes

Mesh-construction algorithm Fundamental representation for geometric modeling and CG Based on a variety of work on polygonal mesh manipulation

Mesh optimization Shape design : Free-form shape design using triangulated

surfaces Surface fairing : A signal processing approach to fair surface

design

Sculpting: an interactive Sculpting: an interactive volumetric modeling techniquevolumetric modeling technique

T. Galyean and J.F. Hughes 1991 SIGGRAPH

Sculpting 3D Voxel DataControlling by 3D Devices

3. User Interface3. User Interface

Physical User Interface Traditional 2D input devices

• Mouse or tablet

Interface Do not use

• WIMP-style direct manipulation techniques

• WIMP = window, icon, menu, pointer

• Standard interface widget

• Button, menu …

Use only freeform strokes on the screen

4. Modeling Operation4. Modeling Operation

Modeling Operation from the User’s point of view Operations are executed after user complete a stroke

Not Supported Creation of Multiple Objects and combining single object Model must have a spherical topology

• E.g torus (x) Strokes do not intersect

Basic Operations Creation, Painting, Extrusion, cutting, erasing

4.1 Overview4.1 Overview

Basic Operation and Result

Summarizing the modeling operation available

Figure 5: example of Creation Operation (top: Stroke, middle: result, bottom: rotation)

Figure 6: example of Extrusion (top: extruding stroke, bottom: result of extrusion)

Figure 7: More Extrusion Operation (digging cave, drawing)

Figure 8: Cutting Operation

Figure 9: Extrusion After Cutting

Figure 10: Smoothing Operation

Figure 11: Examples of Transformation (top: bending, bottom: distorting)

5. Algorithm5. Algorithm

How the system constructs a 3D polygonal mesh from the user’s freeform strokes

Creation and extrusion Freeform surface construction based on skeleton

Input Strokes is Resampled To remove noise in the handwriting input strokes To construct a regular polygonal mesh Smooth polyline with uniform edge length

5.1 Creating a New Object*5.1 Creating a New Object*

Overall Procedure

1. Closed planar polygon

2. Spine or axes of the polygon

3. Elevate vertices of the spine

4. Polygonal mesh wrapping the spine

5.1 Creating a New Object**5.1 Creating a New Object**

Figure 13: Finding the Spine

1. Closed planar polygon (13a) All edges has predefined unit length

External edge: initial polygon

Internal edge: edges added in the triangulation

- Triangulation (13b) Constraint Delaunay Triangulation

Terminal triangle: 2 external edges

Sleeve triangle: 1 external edges

Junction triangle: 0 external edge

5.1 Creating a New Object5.1 Creating a New Object******

5.1 Creating a New Object5.1 Creating a New Object********

2. Spine or axes of the polygon Spine by Chordal Axis (13c)

• Connecting the midpoint of the internal edges

Pruning (13d)

Pruned spine (13e)• Chordal axis of remaining sleeve and junction triangles

Subdivision of sleeve and junction triangle (13f)

5.1 Creating a New Object5.1 Creating a New Object**********

Pruning Merge triangles Removing interior edge

Triangulation with a fan

• Stop 1: Some vertex lies outside the semicircle

• Stop 2: Newly merged triangle is a junction triangle

5.1 Creating a New Object5.1 Creating a New Object************

3. Elevate vertices of the spine

Average distance between vertex and external vertex directly connected to the vertex (b)

4. Polygonal mesh wrapping the spine Elevate fan edge is converted to a quarter oval (c) Sewing together the neighboring elevated edge (d)

5.2 Painting on the Surface5.2 Painting on the Surface

Create surface line Projecting each line segment of the input stroke

onto the object’s surface polygon

Method 1. Calculate bounded plane

2. Find intersections between plane and polygon

Only nearest intersecting polygon is used

5.3 Extrusion*5.3 Extrusion*

Creating new polygonal meshes Stroke: Closed base surface line (base ring)

Extruding stroke

Method Base ring sweep along the projected extruding stroke

Figure 17: Extrusion Algorithm

5.3 Extrusion**5.3 Extrusion**

1. Producing 3D extruding stroke Find the plane for projection

Project 2D extruding stroke onto the plane

2. Pointer Advancing Create copy of the base ring along the extruding stroke

3. Delete original polygon surrounded by the base ring

4. Create new polygon by sewing adjacent rings

5.3 Extrusion***5.3 Extrusion***

Point Advancing Advancing from two end pointer (left, right)

Three possibility

• Left pointer / Right pointer / both

Goodness value

• Increases angle between line connecting two pointers and direction of strokes

Figure 18: Sweeping the Base Ring

5.3 Extrusion****5.3 Extrusion****

User draw unexpected extruding stroke or base surface is not sufficiently planar

Figure 19: Unintuitive Extrusions

5.4 Cutting5.4 Cutting

Based on the painting algorithm

1. Projected onto the front and back facing polygon

2. Connects the corresponding end points of the projected edges to construct a planer polygon

3. Triangulating planer polygon

4. Removing all polygons to the left of the cutting strokes

Figure 20: Cutting

5.5 Smoothing5.5 Smoothing

Determine of Z-value of Vertex Bazier curve between

two end-point of the ring on 2D plane

Figure 21: Smoothing Algorithm

6. Implementation*6. Implementation*

Prototype : 13000 line Java program

Test Devices Display-integrated tablet (Mutoh MVT-14) Electric whiteboard (Xerox Liveboard) Standard mouse

Speed Mesh construction process is real-time if model becomes complicated, it causes a short pause

6. Implementation**6. Implementation**

Figure 2 3D models created with Teddy

Painted using a commercial texture-map editor

• Chameleon

Results reflect the hand-drawn nature of the shape Quite different from 3D models created in other modeling

system

7. User Experience7. User Experience

Feedback of Teddy Quite intuitive

Explore various 3D design

Observation of how first-time users learn teddy Create their own models fluently within 10 minutes

• 5 minutes : tutorial

• 5minutes : guided practices

It takes a few minutes to Create stuffed animal

8. Future Work8. Future Work

Algorithms and Implementation are Robust, Efficient Intuitive result, when user draw unexpected strokes

Research Direction Develop additional modeling operation

• Support a wider variety of shapes with arbitrary topology

• Allow more precise control of the shape

Possible Operation

• Create crease

• Twisting the models

• Specifying the constraints between the separate parts for animation system

Further ResearchFurther Research

Chameleon : 3D Paint for Teddy Paint on 3D Model

System Makes 2D Texture Automatically

Application

Movies

Further ResearchFurther Research

SmoothTeddy 3D Modeling

and Painting System

Application

Movies