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FRE 2645
Unformating SVG DocumentsApplication To Graphic
Document Indexing
Master Training par Norolala Ramangaseheno Tutors
Eric Trupin, Tony Pridmore Date 2005-09-06
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Unformating SVG Documents

• Presentation of the Project
• Environment of Work
• Introducing the Subject
• Unformat Process Applied to Graphics Indexing
• Contributions
• Applications

PSI 2005 N. Ramangaseheno
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Environment of Work

• Laboratories
• DI (Document Interaction) team of PSI
  (Perception, Systèmes, Information) laboratory,
  University of Rouen, France,
• IPI (Image Processing and Interpretation)
  research group of SCSIT (School of Computer
  Science and Information Technology), University
  of Notthingham, England.
• Tutors
• Eric Trupin,  Directeur de Recherche  within
  the PSI,
• Tony Pridmore, Senior Lecturer, member of
  IPIresearch group.
• Collaborations
• Mathieu Delalandre, post-doc within the IPI
  group,
• Karim Zouba, master traineewithin the PSI.
• Integrated project Indexation de graphiques
  vectoriels
• Programming language Java

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Unformating SVG Documents

• Presentation of the Project
• Environment of Work
• Introducing the Subject
• Unformat Process Applied to Graphics Indexing
• Contributions
• Applications

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Vector Graphics

• Common vector formats
• AI (Adobe Illustrator)
• SVG (Scalable Vector Graphic)
• WMF (Windows Metafile)
• EPS (Encapsulted PostScript)
• DXF (AutoCAD)

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Image Indexing
Graphics types - raster images or bitmaps
- vector mages Indexing automatic
extraction of informative characteristics from
multimedia containers to aid retrieval
and browsing through large databases.
Architecture of an image indexing system
Graphic document
Conception of visual descriptors
Image signature
Measure of similarity
Image database
Classification
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Unformating SVG Documents

• Presentation of the Project
• Environment of Work
• Introducing the Subject
• Unformat Process Applied to Graphics Indexing
• Contributions
• Applications

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Diagram of the Indexing System
Generator of synthetic documents
Vector graphic
Unformat process
Low-level representation
Analyzer
High-level representation
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Problem with Unformating
Why unformat before analysing ?
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Problem with Unformating
acquiring
modelling
filtering
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Unformating SVG Documents

• Presentation of the Project
• Contributions
• Diagram of the Unformat System
• The SVG Format
• Parsing
• Modelling
• Filtering
• Intersection Search
• Applications

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Diagram of the Unformat System
parsing
filtering
intersection search
modelling
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Unformating SVG Documents

• Presentation of the Project
• Contributions
• Diagram of the Unformat System
• The SVG Format
• Parsing
• Modelling
• Filtering
• Intersection Search
• Applications

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The SVG Format

• Norm and advantages
• W3C norm for describing 2D graphics gt open
  standard
• Growing format   gt growig number of visualizers
  and users
• Vectorial description of graphical objects gt
  scalablility
• Based on XML (described by a DTD) compatible
  with XLink, XPointer, CSS/XSL, and SMIL
  (animation language) gt textual, separation
  between semantic and presentation
• Scripts and animations started on associated
  events gt interactif
• Inconvenient
• Lack of realism
• Adapté pour
• Interactive geographic maps
• Technical drawings
• XML accounts

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Structure of a SVG Document
Exemple
lt?xml version"1.0" encoding"iso-8859-1"
standalone"no"?gt lt!DOCTYPE svg
PUBLIC "-//W3C//DTD SVG 1.0//EN" "http//www.w3.
org/TR/2001/REC-SVG-20010904/DTD/svg10.dtd"gt ltsvg
width"5cm" height"4cm"gt ltdescgtUn joli
rectanglelt/descgt ltrect x"3cm" y"0.5cm"
width"1.5cm" height"2cm"/gt lt/svggt
SVG tag corresponding declaration
ltsvggt SVG document
ltggt group of objects
ltsymbolgt geometrical shape
lttextgt , lttspangt, ou lttrefgt text
ltimagegt image
ltdefsgt definition of links
ltusegt link towards an internal graphical object
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Geometrical Shapes

• Common shapes
• Ellipse ltellipse cx"400" cy"300" rx"72"
  ry"50" /gt
• Rectangle ltrect x"150" y"50" width"135"
  height"100" /gt
• Circle ltcircle cx"70" cy"100" r"50"
  /gt
• Line ltline x1"375" y1"50" x2"425"
  y2"150" /gt
• Polyline ltpolyline points"50,
  250,75,350,100,250,125,350" /gt
• Polygon ltpolygon points"250,250,297,284,279,
  340,220,340" /gt
• Complex shape
• Path ltpath d"M 50 250 L 100 250 L 150
  300"/gt

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Unformating SVG Documents

• Presentation of the Project
• Contributions
• Diagram of the Unformat System
• The SVG Format
• Parsing
• Modelling
• Filtering
• Intersection Search
• Applications

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• Any XML handling need a parser
• a parser is a syntaxic analyzer it is placed
  between the XML file and the application
• a parser can be used
• from a program (script, java, C)
• from a navigator
• SAX, event driven parser
• handler methods called from special events
• file sequentially analyzed before being
  transmitted to the application

Handler
startDocument() startElement() endElement() endDoc
ument()
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Unformating SVG Documents

• Presentation of the Project
• Contributions
• Diagram of the Unformat System
• The SVG Format
• Parsing
• Modelling
• Filtering
• Intersection Search
• Applications

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Graphical Objects Modelling

• GOMLib Delalandre 2004
• Graphical Objects Modelling Library
• XML and SVG export
• Multi-model different representations possible
  

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Unformating SVG Documents

• Presentation of the Project
• Contributions
• Diagram of the Unformat System
• The SVG Format
• Parsing
• Modelling
• Filtering
• Intersection Search
• Applications

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Need filtering to respect orders 1 point of a 2D
planimetry 1 single representation
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Preliminary Tests (1/2)

• Given - two lines L1 et L2
• - b1(xb1,yb1) begin point of L1 b2(xb2,yb2)
  begin point of L2
• - e2(xe2,ye1) end point of L1 e2(xe2,ye2) end
  point of L2
• L1 isEqual L2 L1 and L2 are equal if
• xb1 xb2 yb1 yb2 xe1 xe2
  ye1 ye2
• L1 isParallel L2 L1 and L2 are parallel if
• (( xe1 - xb1 ) ( xe2 - xb2 ) - ( ye1 - yb1 )
  ( ye2 - yb2 )) 0
• L1 isColinear p a point p(x,y) is colinear to
  L1 if
• y t x o
• (t ( ye1 - yb1 ) / (xe1 - xb1 ) and
  o yb1 - t xb1 )
• L1 isColinear L2 L2 is colinear to L1 if
• L1 isColinear b2 and L1 isColinear e2
  

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Preliminary Tests (2/2)

• L1 overlaps p L1 overlaps a point p(x,y) if
• (( x - xb1 ) ( x - xe1 )) lt 0 or
  (( y - yb1 ) ( y - ye1 )) lt 0
• L1 overlaps L2 L1 overlaps L2 if
• L1 overlaps( b2 ) or L1 overlaps( e2
  )
• L1 isConnected p L1 is connected to the point
  p(x,y) if
• b1 p
• or e1 p
• L1 isConnected L2 L1 is connected to L2 if
• L1 isConnected b2
• or L1 isConnected e2

l1 is connected to l2
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Filtering Tests (1/3)

• L1 sameAs L2 L1 and L2 are the same if
• L1 isEqual L2
• or xb1 xe2 yb1 ye2
  xe1 xb2 ye1 yb2
• in this case, line L2 is filtered (erased)

l1 same as l2
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Filtering Tests (2/3)

• L1 includes L2 L1 includes L2
• case (a) L2 totally included inside L1
• if L1 isColinear L2
• and L1 overlaps b2
• and L1 overlaps e2
• case (b) L2 included inside and connected to L1
• or L1 isConnected L2
• and L1 isParallel L2
• and L1 overlaps b2 or L1 overlaps e2

(a)
(b)
l1 includes l2
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Filtering Tests (3/3)

• L1 isJoined L2 L1 and L2 join
  together
• case (a) L1 is extended by L2, without
  overlapping
• if L1 isConnected L2
• and L1 isParallel b2
• and L1 overlaps e2  is false
• case (b) L1 is extended by L2, with overlapping
• or L1 isColinear L2
• and L1 overlaps L2
• and L2 overlaps L1

(a)
(b)
l1 and l2 join together
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Unformating SVG Documents

• Presentation of the Project
• Contributions
• Diagram of the Unformat System
• The SVG Format
• Parsing
• Modelling
• Filtering
• Intersection Search
• Applications

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Get Line Intersection (1/3)
X junction
T junction
Segments separation
Multi-degree junction
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Get Line Intersection (2/3)

• Intersections processing algorithm
• Search and list all junctions of the document,
• For each line, test if it contains the junction
• If yes, break the line in two at the junction
  point
• Used tests
• L1 isIntersected L2 L1 and L2
  intersects themselves on a point p(x,y)
• so that p lt-- L1 getIntersection L2
• case (a) X junction
• if p is not null
• case (b) T junction
• if p is null
• L1 overlaps p and L2 overlaps p
• or L1 isConnected p and L2 overlaps p
• or L2 isConnected p and L1 overlaps p
• In both cases, add junction p(x,y) to the
  junctions list

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Get Line Intersection (3/3)

• 2. L1 is regular, L2 irregular
• Two cases
• L2 is horizontal
• y1 a1 x1 b1
• x2 c
• -?? y2 ? ?
• yc c
• xc (c - b1)/ a1
• L2 is vertical
• y1 a1 x1 b1
• y2 c
• -?? x2 ? ?
• xc c
• yc a1 c b1

• L1 isIntersected L2 returns
• intersection point p(xc,yc) between lines L1 and
  L2
• null if lines are parralel or colinear
• null if xlt0 , ylt0
• Four cases to take into account
• 1.L1 and L2 are regular
• y1 a1 x1 b1
• y2 a2 x2 b2
• yc y1 y2
• xc x1 x2
• xc (b2 - b1)/(a1 - a2)
• yc a1 xc b1 a2 xc b2
• 4. L1 and L2 are irregular (see case 2.)

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Unformating SVG Documents

• Presentation of the Project
• Contributions
• Applications

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Experiments Results (1/3)
Unformating results on SVG documents created with
the 2gT system ("graphic ground Truth").
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Experiments Results (2/3)

• Colour index
• black vectors no change
• red vectors filtered vectors
• blue vectors  broken vectors
• visually , all original lines are retrieved
• After reduction, we do see that all intersections
  have been erased

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Experiments Results (3/3)

• Algorithm complexity n(n-1)
• Filtering n (n-1) (n-2) 1
  comparaisons
• Intersections retrieval n (n-1) (n-2)
  1 comparaisons
• Runtime about 1,5 min for 100 documents (2500
  vectors and 100 intersections per document)

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Conclusion

• Outcome
• Technical achievement
• Unformating system effective and functional

Perspectives Use upstream pattern recognition
tools
PSI 2005 N. Ramangaseheno