KelpFusion :A Hybrid Set Visualization Technique

Copyright of figures and other materials in the paper belongs original authors.

Presented by Sanghyeok LEE

2014. 12. 23

Computer Graphics @ Korea University

IEEE Transactions o visualization and computer graphics (2013)

Meulemans et al.

Sanghyeok Lee | 2015. 01. 06 | # 2Computer Graphics @ Korea University

Part 1. Introduction1. Introduction

2. Related work

Part 2. Algorithm3. KelpFusion overview

4. KelpFusion analysis

Part 3. Verification5. User Study

6. Conclusion and Future work

Index

Part 1. Introduction

KelpFusion : A Hybrid Set Visualization Technique

Sanghyeok Lee | 2015. 01. 06 | # 4Computer Graphics @ Korea University

1. Introduction

Exploring large information spaces

• Grouping of elements by their properties

Sanghyeok Lee | 2015. 01. 06 | # 5Computer Graphics @ Korea University

• Venn diagrams

• Euler diagrams

• 문제점

복잡한 교차점

타원

1. Introduction

Sets and elements representation

Sanghyeok Lee | 2015. 01. 06 | # 6Computer Graphics @ Korea University

• Bubble Sets

폐색

• LineSets

• Kelp Diagrams

1. Introduction

Sets and elements representation (2)

Sanghyeok Lee | 2015. 01. 06 | # 7Computer Graphics @ Korea University

• Kelp Diagram 의 발전형

Spanning graph

+ shortest-path graph

• Hybrid technique

mix of hulls and lines

• Minimal spanning tree + convex hull

fitted boundaries for groups of elements

• Interactive manipulation

𝒕, 𝑨 parameter

• Hypergraph visualization

1. Introduction

About KelpFusion

Sanghyeok Lee | 2015. 01. 06 | # 8Computer Graphics @ Korea University

1. Introduction

About KelpFusion (2)

Sanghyeok Lee | 2015. 01. 06 | # 9Computer Graphics @ Korea University

• Popular ways to visually represent set intersections

• Papers

automatically drawing

adding labels or glyphs

2. Related Work

Venn, Euler diagrams

Citation [14] Citation [16] Citation [15]

Sanghyeok Lee | 2015. 01. 06 | # 10Computer Graphics @ Korea University

• A method based on ‘isocontours’ (level sets) to overlay such an arrangement with enclosing set regions

• Readability of regions in these methods suffers when they are highly overlapping

2. Related Work

Bubble sets

Sanghyeok Lee | 2015. 01. 06 | # 11Computer Graphics @ Korea University

• Improve the readability of complex set intersections

• LineSets

set : simple curved line 으로 표현

grouping 의 새로운 개념 제안

• Kelp diagrams

bubble and stick, + hypergraph 개념 확장

• 주요특징

set 과 member 를 특정 위치에 고정

2. Related Work

LineSets and Kelp diagrams

Sanghyeok Lee | 2015. 01. 06 | # 12Computer Graphics @ Korea University

• Kelp Diagram 의 발전형

Spanning graph

+ shortest-path graph

• Hybrid technique

mix of hulls and lines

• Minimal spanning tree + convex hull

fitted boundaries for groups of elements

• Interactive manipulation

𝒕, 𝑨 parameter

2. Related Work

About KelpFusion (again)

Part 2. Algorithm

KelpFusion : A Hybrid Set Visualization Technique

Sanghyeok Lee | 2015. 01. 06 | # 14Computer Graphics @ Korea University

• Hybrid

edges + filled faces

• Interaction

User-controlled tradeoff

• minimal spanning tree convex hull

• Kelp Diagrams 과의 차이점

filled faces 의 규칙 추가

legibility rules 의 추가

edges 의 생성 규칙

3. KelpFusion overview

Features

Sanghyeok Lee | 2015. 01. 06 | # 15Computer Graphics @ Korea University

• Kelp diagrams

minimal spanning tree

detour(우회로) 요소

• KelpFusion

minimal spanning tree

shortest-path graph

• 더 많은 의미 부여

• filled faces 의 다양성

3. KelpFusion overview

Edges definition

Sanghyeok Lee | 2015. 01. 06 | # 16Computer Graphics @ Korea University

• 용어 정리

𝑵 : set of nodes

𝑺𝟏, … , 𝑺𝑲 : sets (앞 뒤 순서를 결정)

𝒗 : nodes (assigned unique allocation area)

allocation area : 각 node들이 확보한 여백. Voronoi cell 로 정의

• Voronoi cell (시드 점들과의 거리에 따라 평면을 분할한 그림)

𝒓 ∶ radius of allocation area

𝒘 ∶ rendered edge width

3. KelpFusion overview

Preliminaries (예비절차)

Sanghyeok Lee | 2015. 01. 06 | # 17Computer Graphics @ Korea University

• 𝑺𝟏, … , 𝑺𝑲 : sets (앞 뒤 순서를 결정)

front-to-back ordering

• How?

try all possible orderings? X

number of intersection? X

그냥 set 의 사이즈가 작은 순서대로 앞으로 배정 O

• the most readable results

• heuristic solution

3. KelpFusion overview

Set order

Sanghyeok Lee | 2015. 01. 06 | # 18Computer Graphics @ Korea University

• 3 phase

shortest-path graph

fillable faces

visualization

3. KelpFusion overview

Algorithm overview

Sanghyeok Lee | 2015. 01. 06 | # 19Computer Graphics @ Korea University

• 2 parameter

𝒕 (phase 1)

• control the density of the graph

𝑨 (phase 2)

• control the size of the fillable faces

• Phase-by-phase basis, rather than set by set

Possibilities for parallel processing

3. KelpFusion

Algorithm overview (2)

Sanghyeok Lee | 2015. 01. 06 | # 20Computer Graphics @ Korea University

Reachability graph G (superset)

Shortest-path graph (t )

• Algorithm

Fillable Faces (A )

• Three rules (면적, 포함관계, 불명확성)

Visualization

• Smoothing, Color, outline, transparency

Implementation

• 각 단계별 속도향상 정책

3. KelpFusion

Summary

Sanghyeok Lee | 2015. 01. 06 | # 21Computer Graphics @ Korea University

• reachability graph 𝑮

𝑮 contains an edge for each pair of nodes 𝑢, 𝑣 in 𝑆𝑖

edge 𝑢, 𝑣 and its length

• Shortest Euclidean route between 𝑢 and 𝑣

• Avoid allocation area (with 0.5 𝒘)

• Visibility tangent graph

4. KelpFusion analysis

Algorithm – Phase 1: Shortest-path graph

Sanghyeok Lee | 2015. 01. 06 | # 22Computer Graphics @ Korea University

• Shortest-path graph

𝒕 값에 따라 변동 (𝒕 ≥ 1)

• minimal spanning tree convex hull 변동

SPG(Si, t) 알고리즘

SPG(Si, 1) : complete graph(convex hull)

SPG(Si, ∞) : minimal spanning tree

4. KelpFusion analysis

Algorithm – Phase 1: Shortest-path graph (2)

Sanghyeok Lee | 2015. 01. 06 | # 23Computer Graphics @ Korea University

4. KelpFusion analysis

Algorithm – Phase 1: Shortest-path graph (3)

Sanghyeok Lee | 2015. 01. 06 | # 24Computer Graphics @ Korea University

• face를 채우는 것의 장단점

• 4가지 rule

4. KelpFusion analysis

Algorithm – Phase 2: Fillable faces

Sanghyeok Lee | 2015. 01. 06 | # 25Computer Graphics @ Korea University

• Smooth the polygon boundary

• Unique color

• Thin gray outline

• Subtract the allocation area

• Slight transparency(20 percent)

4. KelpFusion analysis

Algorithm – Phase 3: Visualization

Sanghyeok Lee | 2015. 01. 06 | # 26Computer Graphics @ Korea University

• Phase 1

reachability graph 𝑮 들로네삼각분할(Delaunay triangulation) 로 정의

• Superset 의 크기 감소: 계산감소

𝒕 –value precomputing

• Allowing for interactivity

Insertion order 재설정

• 𝒕 -value 가 줄어듦에 따라graph가 성장 weight 에 가중치를 줘서 order

변경. visualization 부분의 계산을빠르게 해줌

4. KelpFusion analysis

Implementation속도향상을 위한 phase 1 구현 최적화 방향

Sanghyeok Lee | 2015. 01. 06 | # 27Computer Graphics @ Korea University

• 𝒕 -value, 𝑨 -value

Interactively

Independently

• Result (see fig)

4. KelpFusion analysis

Implementation (2)

Sanghyeok Lee | 2015. 01. 06 | # 28Computer Graphics @ Korea University

• Allocation area

• Thinning areal features

• Right-angle crossings

4. KelpFusion analysis

Other Design Considerations

Part 3. Verification

KelpFusion : A Hybrid Set Visualization Technique

Sanghyeok Lee | 2015. 01. 06 | # 30Computer Graphics @ Korea University

• 실험 설계

Bubble Sets 과 LineSets 기법 각각 비교

3가지 기법 x 4가지 example x 2가지 난이도 x 3번 반복

13명의 참가자

• 왜 Kelp Diagram 기법과는 비교를 안 하나?

현 실험에서는 더 이상의 조건을 추가하여 실험하는 것은참가자들의 피로를 줄 수 있음

5. User Study

Method

VS

Bubble Sets LineSets KelpFusion

Sanghyeok Lee | 2015. 01. 06 | # 31Computer Graphics @ Korea University

• Data sets

Real data of restaurant locations in the Boston area (from Bing Maps)

• Tasks

Multiple-choice answers to encourage participants to rely on their visual perception

5. User Study

Method

Sanghyeok Lee | 2015. 01. 06 | # 32Computer Graphics @ Korea University

• Participants and apparatus(장치)

13 participants (7 male and 6 females)

Age : 27~47 (mean age : about 28)

Not programmers

None being colorblind

Individual PC, using a 24’’ widescreen monitor(1900x1200)

• Procedure(절차)

Instructed with each visualization technique

Advancing from easier to harder tasks

Isomorphic question : flipped horizontally and vertically

Limit each question time : 40 seconds

Measuring accuracy and completion time

5. User Study

Method (2)

Sanghyeok Lee | 2015. 01. 06 | # 33Computer Graphics @ Korea University

H1 : • KelpFusion 과 LineSets은 이미지가 겹치는 부분을 줄여 Bubble Sets 보다 빠르고

정확할 것이다.

H2 :• KelpFusion 은 LineSet보다 더 좋은 overview를 제공할 것. SizeOverview 에서 더

좋을 것이다.

H3 :• KelpFusion 의 closed face 는 LineSet의 지그재그보다 더 명확하여

SetIntersection 에서 더 좋을 것이다.

H4 : • LineSet 은 선으로 순차적으로 연결되어 KelpFusion 보다 SizeCount 에서 더

좋을 것이다.

H5 :

• KelpFusion 은 밀집공간에서도 각 노드를 잘 표현하여 Setmembership에서더 좋을 것이다.

H6 :• KelpFusion 과 Bubble sets은 LineSets 보다 그룹을 더 잘 표현할 것이다.

H7 :

• KelpFusion 은 LineSet보다 미학적이고, Bubble sets보다 덜 어수선할것이다.

5. User Study

Hypotheses

Sanghyeok Lee | 2015. 01. 06 | # 34Computer Graphics @ Korea University

5. User Study

Results

• RM-ANOVA (반복측정 분산분석)

반복되는 측정값을 가진 군간의 유의성을 알아보고자 하는 경우

정확도 평균 정답시간 평균

Sanghyeok Lee | 2015. 01. 06 | # 35Computer Graphics @ Korea University

5. User Study

Results (2)

• Subjective user ratings for each technique

Error bars represent two standard errors. Significant differences are observed in all rankings

1 : bad5 : good

Sanghyeok Lee | 2015. 01. 06 | # 36Computer Graphics @ Korea University

5. User Study

Summary and Limitations H1 : 검증

• KelpFusion 과 LineSets은 이미지가 겹치는 부분을 줄여 Bubble Sets 보다 빠르고정확할 것이다.

H2 : 검증• KelpFusion 은 LineSet보다 더 좋은 overview를 제공할 것. SizeOverview 에서 더

좋을 것이다.

H3 : 검증 실패• KelpFusion 의 closed face 는 LineSet의 지그재그보다 더 명확하여

SetIntersection 에서 더 좋을 것이다.

H4 : 거짓으로 검증• LineSet 은 선으로 순차적으로 연결되어 KelpFusion 보다 SizeCount 에서 더

좋을 것이다.

H5 : 검증 실패

• KelpFusion 은 밀집공간에서도 각 노드를 잘 표현하여 SetMombership에서더 좋을 것이다.

H6 : 검증• KelpFusion 과 Bubble sets은 LineSets 보다 그룹을 더 잘 표현할 것이다.

H7 : 검증

• KelpFusion 은 LineSet보다 미학적이고, Bubble sets보다 덜 어수선할것이다.

Sanghyeok Lee | 2015. 01. 06 | # 37Computer Graphics @ Korea University

1. KelpFusion 의 강점 정리

1. Hybrid

2. Single parameter

2. 실험 정리

1. 가장 뛰어난 기법으로 검증

2. 정확성에서 bubble sets 보다 명확히 뛰어남

3. 정확성에서 LineSets 보다 약간 뛰어남

4. 완료시간에서 두 기법보다 명확히 뛰어남

5. linear와 areal을 합친 기법은 좋은 시각화 방법임을 검증

3. Future work

1. 다른 기존 기법과 마찬가지로, 교차구간의 복잡성 해결이 시급

2. 큰 데이터 셋을 interactive하게 통합하는 기법 필요

3. visualization 단에서 요소를 추가 삭제하는 안정성 필요

6. Conclusion and Future work