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Image Processing and Interpretation GroupUniversity of Nottingham
Eureka Meeting, L3i Laboratory, La Rochelle UniversityTuesday 20th April 2006
Fast Building of Region Graph from SVG
Mathieu Delalandre, Zouba Karim, Norolala Ramangaseheno
Supervisors Tony Pridmore (IPI, Nottingham University, UK)
Eric Trupin (PSI, Rouen University, France)
Image Processing and Interpretation GroupUniversity of Nottingham
Eureka Meeting, L3i Laboratory, La Rochelle UniversityTuesday 20th April 2006
<rect x="400" y="100" width="400“ height="200"fill="yellow" stroke="navy" stroke-width="10" />
(a) (b)
Common formats :
• AI (Adobe Illustrator)
• SVG (Scalable Vector Graphic)
• WMF (Windows Metafile)
• EPS (Encapsulted PostScript)
• DXF (AutoCAD)
•ClipArt
•Flash
Example
WMF pen EPS plane
IntroductionWhat are Vector Graphics ?
ClipArt Cheese
Image Processing and Interpretation GroupUniversity of Nottingham
Eureka Meeting, L3i Laboratory, La Rochelle UniversityTuesday 20th April 2006
IntroductionVector Graphics Indexing & Retrieval (1/2)
• Vector graphics are growing on Web and databases • [Mong’03] [Chen’04] [Kang’04] …
• Few I&R systems have been developed (> 2000)• [Love-01] [Sciascio’04] [Dosch’04] [Fonseca’05]
[Rusiñol’05] [Zakaria’05] …
Vector Graphics
Features Extraction Matching
Index Ranking
Image Processing and Interpretation GroupUniversity of Nottingham
Eureka Meeting, L3i Laboratory, La Rochelle UniversityTuesday 20th April 2006
IntroductionVector Graphics Indexing & Retrieval (2/2)
• Line Graph [Dosch’04] [Zakaria’05] …• Symbol recognition
• Region Graph [Fonseca’05] [Rusiñol’05] ..• Document indexing
• Our works region graph extraction for SVG Indexing and Retrieval large sized data a fast approach • Two steps : unformat SVG and region graph building
Image Processing and Interpretation GroupUniversity of Nottingham
Eureka Meeting, L3i Laboratory, La Rochelle UniversityTuesday 20th April 2006
Unformat SVGUnformat process, what is it ?
Example: overlapped rectangles
L1 L2
R3
R1
R2
L3L4
<rect x="400" y="100" width="400" height="200"fill="blue" /><rect x="650" y="200" width="400" height="200"fill="yellow" />
R2R1 R3
?
to unformat (or to broke) SVG
Image Processing and Interpretation GroupUniversity of Nottingham
Eureka Meeting, L3i Laboratory, La Rochelle UniversityTuesday 20th April 2006
filtering
Parsing for line extraction
SVG document
Unformat SVG Overview of our approach
set of (joined) lines set of no joined lines
Image Processing and Interpretation GroupUniversity of Nottingham
Eureka Meeting, L3i Laboratory, La Rochelle UniversityTuesday 20th April 2006
Unformat SVGWhy using a filtering step
you see 5 lines you have 9 lines
Image Processing and Interpretation GroupUniversity of Nottingham
Eureka Meeting, L3i Laboratory, La Rochelle UniversityTuesday 20th April 2006
Unformat SVG Our filtering process
l1 includes l2
l1 same as l2
l1 joins l2
(a)
(b)
(a)
(b)
(a)
(b)
l1 intersects and overlaps l2
l1 intersects only l2
Image Processing and Interpretation GroupUniversity of Nottingham
Eureka Meeting, L3i Laboratory, La Rochelle UniversityTuesday 20th April 2006
Unformat SVGExamples of results
crossing point merged lines
Image Processing and Interpretation GroupUniversity of Nottingham
Eureka Meeting, L3i Laboratory, La Rochelle UniversityTuesday 20th April 2006
Region Graph BuildingHow it works ?
K Lines Line Graph
Finding regions and their links
Image Processing and Interpretation GroupUniversity of Nottingham
Eureka Meeting, L3i Laboratory, La Rochelle UniversityTuesday 20th April 2006
Region Graph BuildingApproaches used in the literature
• Approaches based on graph handling [Fonseca’05] ..• region detection = problem of finding minimum length
cycles inside a graph
Image Processing and Interpretation GroupUniversity of Nottingham
Eureka Meeting, L3i Laboratory, La Rochelle UniversityTuesday 20th April 2006
• Based on [Weindorf’01] works : using vectorial information
Definition: direct angle = anticlockwise
Region Graph BuildingOur approach (1/3)
L1
L5L2L4
L3
L1
L4 L5 L2
L3
Vector Graphic document Line Graph
e
b
e
be
e
e: end of a Line
b: beginning of a Line α:Direct angle between 2 Lines
beeb
b
b
eb
b
ee
L1
L4 L2L5
L3
Specialized Line Graph
α(2-1)
α(1-2)
b2,e1e1,b2
e4,b1
b1,e4
Image Processing and Interpretation GroupUniversity of Nottingham
Eureka Meeting, L3i Laboratory, La Rochelle UniversityTuesday 20th April 2006
[Clementini’93]
a b a bab
b
a
adjacency overlap strict and tangential inclusion
Region Graph Building Our approach (2/3)
a b
neighboring
R1
Ymax
Ymax
Ymin
Ymin
Xmin Xmin Xmax Xmax
R2
[Xmin < Xmin & Xmax > Xmax] & [Ymin < Ymin & Ymax > Ymax]
Image Processing and Interpretation GroupUniversity of Nottingham
Eureka Meeting, L3i Laboratory, La Rochelle UniversityTuesday 20th April 2006
Region Graph Building Our approach (3/3)
Image Processing and Interpretation GroupUniversity of Nottingham
Eureka Meeting, L3i Laboratory, La Rochelle UniversityTuesday 20th April 2006
Conclusion and Perspectives
• Conclusion• First system dealing with unformating problems• First system allowing to build region graph from large sized
documents and from large sized databases
• Perspectives• Extend to curves and arcs processing • Extend built graphs with neighboring relations• Reduce the unformat complexity step using a zone sorting
algorithm• Use it for retrieval and indexing (not only graph building)