The Management of Spatial and Temporal Constraints in GIS using Pictorial Interaction on the Web

1
The Management of Spatial and Temporal
Constraints in GIS using Pictorial Interaction on
the Web

• Fernando Ferri IRPPS-CNR-Italy
• Patrizia Grifoni IRPPS-CNR-Italy
• Maurizio Rafanelli IASI-CNR-Italy

2
The problem

• To make available geographical databases by Web

3
The aim of the paper

• XPQL (eXtended Pictorial Query Language) mapped
  in Geographic Markup Language (GML 3.0).

4
The eXtended Pictorial Query Language

• The XPQL query language has
• a set of spatial operators
• G-union, G-difference, G-disjunction, G-touching,
  G-inclusion, G-crossing, G-pass-through,
  G-overlapping, G-equality, G-distance, G-any and
  G-alias
• a set of temporal operators
• T-before, T-meets, T-overlaps, T-starts,
  T-during, T-finishes and T-equals
• symbolic geographical objects (sgo).

5
Symbolic geographical objects

• sgo definition
• ltid, objclass, S, ? gt
  where
•    id is the sgo identifier
• objclass is the set (possibly empty) of classes
  iconized by ?
• S represents the attributes to which the user can
  assign a set of values. Some attributes can be
  referred to a temporal dimension
• ? is the ordered set of pairs (h, v), which
  defines the spatial characteristics and position
  of the sgo with respect to a reference point in
  the working area.

6
Geometric characteristics of an sgo

• Let y be an sgo, we have
• ?y geometric border of y it is defined
  as
• if y is a polygon, ?y is the set of its
  accumulation points (as defined in the set
  theory)
• if y is an open polyline, ?y is formed by its
  extreme points
• if y is a point ?y is the empty set.
• y y - ?y geometrical interior of y

7
Geometric characteristics of an sgo

• Dim( y)
• 0 if y contains at least one point but no
  polylines or polygons
• 1 if y contains at least one polyline but no
  polygons
• 2 if y contains at least one polygon.  

8
The spatial operators of XPQL

• G-union definition (Uni) The G-union of two sgo
  y i and y j is a new sgo defined as the set of
  all points belonging to y i e and/or y j.
• G-touching definition (Tch) G-touching between
  two sgo y i and y j exists iff the points common
  to the two y are all contained in the union of
  their boundaries. If this condition is satisfied,
  the result of this operation between y i and y j
  is a new ? called ?h and defined by the set of
  points common to y i and y j.

9
The spatial operators of XPQL

• G-inclusion definition (Inc) An sgo y i
  G-includes another sgo y j (and we write ? i Inc
  ? j) iff all the points of y j are also points of
  y i. The result is an sgo yh which coincides with
  the second operand y j.
• G-disjunction definition (Dsj) Two sgo y i and y
  j are G-disjoined between them (formally ? i Dsj
  ? j) if the intersection of their borders AND the
  intersection of their internal points is null.

10
The spatial operators of XPQL

• G-pass-through definition (Pth) Let y i be a
  polyline and let y j be a polygon. Then, the
  operator G-pass-through is applicable iff the
  polyline is partially inside the polygon
  (formally ? i Pth ? j).

11
The spatial operators of XPQL

• G-distance definition (Dst) Let y i, yj Î A be
  two sgo of any type. Their distance is valuable
  and and gt0 iff their intersection is null. The
  (minimum) distance Dst (f min) between them is
  a numeric value that represents this distance.
  This operator can be used to find all sgo having
  distance ? (? being one of the following symbols
  gt, lt, , , , ?) from the reference sgo. The
  distance ( df ) value is given by df (yi,
  yj)? yh where
• yh indicates a bi-oriented segment representing
  the distance operator between y i , yj
• f is the qualifier which solves this ambiguity
• ? is a selection expression that includes
  conventional operators (gt, lt, , ?, etc.) or
  methods that behave like operators.

12
The spatial operators of XPQL

• G-difference definition (Dif) Let yi, yj Î A be
  two sgo. The difference between two symbolic
  objects y i and yj is defined as a new sgo (yh)
  which contains all the points which belong to yi
  but not to yj.
• G-crossing definition (Crs) Let , yi Î A be two
  polylines, and let yi ? yj ? Æ. Then, Cross yi
  Crs yj yhx x Î yi ? yj and y h Î A.
• G-overlapping Definition (Ovl) Let yi, yj Î A be
  two sgo of the same type. A non-null overlap
  exists between them iff their intersection is
  also non-null and has the same dimension as the
  sgo.

13
The spatial operators of XPQL

• G-equality definition (Eql) Two symbolic
  geographical objects y i and y j are
  topologically equal if they are of the same type
  and have the same shape.
• G-any Definition (Any) Let ?i, ?j ? A be two
  sgo. Between them any admissible relationship is
  valid if the G-any operator is applied between
  them.
• G-alias Definition (Als) Let yi be a sgo. yj is
  an alias of yi if the only difference between
  them is their shape.

14
The temporal operators of XPQL

• T-before (Bef) Definition An attribute sy ih of
  the sgo yi is T-before another attribute sy jk
  of the sgo yj if sy ih takes values (of the
  interval or instant) temporally before sy jk
  (of the interval or instant). The attributes can
  take both intervals and instants as values.
• T-meets (Mts) Definition An attribute sy ih of
  the sgo yi T-meets another attribute sy jk of
  the sgo yj if sy ih takes the maximum value (of
  the interval or instant) temporally coincident
  with the minimum value of syjk (of the interval
  or instant). The attributes can take both
  intervals and instants as values.

15
The temporal operators of XPQL

• T-overlap (TOv) Definition An attribute sy ih
  of the sgo yi T-overlaps another attribute sy jk
  of the sgo yj if sy ih takes the minimum value
  temporally before the minimum value of s? jk
  and the maximum value temporally after the
  minimum value of sy jk . Both attributes can
  take intervals as values.
• T-starts (Sts) Definition An attribute sy ih of
  the sgo yi T-starts another attribute sy jk of
  the sgo yj if sy ih takes the minimum value (of
  the interval or instant) temporally coincident
  with the minimum value of sy jk (of the interval
  or instant). The attributes can take both
  intervals and instant as values.

16
The temporal operators of XPQL

• T-during (Drg) Definition An attribute sy ih of
  the sgo yi is defined as T-during another
  attribute sy jk of the sgo yj if sy ih takes
  the minimum value temporally after the minimum
  value of s? jk and the maximum value temporally
  before the maximum value of sy jk . Both
  attributes can take intervals as values.
• T-finishes (Fns) Definition An attribute s? iof
  the sgo T-finishes another attribute sy jk of
  the sgo yj if sy ih takes the maximum value (of
  the attribute or instant) temporally coincident
  with the maximum value of sy jk (of the interval
  or instant). The attributes can take both
  intervals and instants as values.

17
The temporal operators of XPQL

• T-equals (Tes) Definition An attribute s? ih of
  the sgo ?i T-equals another attribute sy jk of
  the sgo yj if sy ih takes the minimum and
  maximum values (of the interval or instant)
  temporally coincident with the minimum and
  maximum values of sy jk (of the interval or
  instant). The attributes can take both intervals
  and instants as values.

18
Translating from XPQL to GML

• GML is used for coding the XPQL operands,
  operators.
• There are spatial and temporal operands

19
Spatial feature

• XPQL features are
• Point, Polyline, Polygon.
• Their GML representation
• geometric classes PointType, LineStringType and
  PolygonType

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PointType

• Complex Type PointType
• ltcomplexType name"PointType"gt
• ltcomplexContentgt
• ltextensionbase"gmlAbstractGeometricPrimitiveTy
  pe"gt
• ltsequencegt
• ltchoicegt
• ltelement ref"gmlpos" /gt
• ltelement ref"gmlcoordinates"
• ltelement ref"gmlcoord"
• lt/choicegt
• lt/sequencegt
• lt/extensiongt
• lt/complexContentgt
• lt/complexTypegt

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LineStringType

• Complex Type LineStringType
• ltcomplexType name"LineStringType"gt
• ltcomplexContentgt
• ltextension base"gmlAbstractCurveType"gt
• ltsequencegt
• ltchoicegt
• ltchoice minOccurs"2" maxOccurs"unbounded"gt
  
• ltelement ref"gmlpos" /gt
• ltelement ref"gmlpointRep" /gt
• ltelement ref"gmlcoord" /gt
• lt/choicegt
• ltelement ref"gmlcoordinates" /gt
• lt/choicegt
• lt/sequencegt
• lt/extensiongt
• lt/complexContentgt
• lt/complexTypegt

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PolygonType

• Complex Type PolygonType
• Complex Type PolygonType
• ltcomplexType name"PolygonType"gt
• ltcomplexContentgt
• ltextension base"gmlAbstractSurfaceType"gt
• ltsequencegt
• ltelement ref"gmlexterior" minOccurs"0"
  /gt
• ltelement ref"gmlinterior" minOccurs"0"
  maxOccurs"unbounded" /gt
• lt/sequencegt
• lt/extensiongt
• lt/complexContentgt
• lt/complexTypegt

23
Temporal features

• XPQL features are
• Instant and interval.
• Their GML representation
• TimeInstant and TimePeriod

24
TimeInstant

• ltelement name"TimeInstant" type"gmlTimeInstantT
  ype"
• substitutionGroup "gml_TimePrimitive"/gt
• ltcomplexType name"TimeInstantType"
  final"all"gt
• ltcomplexContentgt
• ltextension base"gmlTimePrimitiveType"gt
• ltsequencegt
• ltelement ref"gmltimePosition"/gt
• lt/sequencegt
• lt/extensiongt
• lt/complexContentgt
• lt/complexTypegt

25
TimePeriod

• ltelement name"TimePeriod" type"gmlTimePeriodTyp
  e" substitutionGroup"gml_TimePrimitive"/gt
• ltcomplexType name"TimePeriodType"
  final"all"gt
• ltcomplexContentgt
• ltextension base"gmlTimePrimitiveType"gt
• ltsequencegt
• ltelement ref"gmlbegin"/gt
• ltelement ref"gmlend"/gt
• ltelement ref"gml_duration"
  minOccurs"0"/gt
• lt/sequencegt
• lt/extensiongt
• lt/complexContentgt
• lt/complexTypegt
• ltelement name"begin" type"gmlTimeInstantProp
  ertyType"/gt
• ltelement name"end" type"gmlTimeInstantProper
  tyType"/gt
•  

26
Coding spatial and temporal operators

• The XPQL temporal operators are derived from GML
  AssociationType
• For the XPQL spatial operators,
  FeaturePropertyType is a particular class of
  properties (using the gmlAssociationType
  pattern) which defines associations between
  features.

27
AssociationType

• ltcomplexType name"AssociationType"gt
• ltsequencegt
• ltelement ref"gml_Object" minOccurs"0"/gt
• lt/sequencegt
• ltattributeGroup ref"gmlAssociationAttributeGrou
  p"/gt
• lt/complexTypegt
• ltelement name"_association" type"gmlAssociation
  Type"
• abstract"true"/gt
•  

28
FeaturePropertyType

• ltcomplexType name"FeaturePropertyType"gt
• ltsequencegt
• ltelement ref"gml_Feature" minOccurs"0"/gt
• lt/sequencegt
• ltattributeGroup ref"gmlAssociationAttributeGroup
  "/gt
• lt/complexTypegt

29
Query expressed by GML

• Find all roads built between the years 1980 and
  1990 that pass through provinces created after
  1975

30
Query expressed by GML

• type definitions for operators
• --gt
• ltcomplexType name"G-pass-throughType"gt
• ltcomplexContentgt
• ltextension base"gmlFeaturePropertyType"gt
  
• ltsequencegt
• ..
• lt/sequencegt
• lt/extension gt
• lt/complexContentgt
• lt/complexTypegt
• ltcomplexType name"T-beforeType"gt
• ltcomplexContentgt
• ltextension base"gmlAssociationType"gt
• ltsequencegt
• ..
• lt/sequencegt

31
Query
expressed by GML

• lt!--
• type definitions for different geographical
  layers
• --gt
• ltcomplexType name"ProvinceType"gt
• ltcomplexContentgt
• ltextension base"gmlPolygonType"gt
• ltsequencegt
• ..
• lt/sequencegt
• lt/extensiongt
• lt/complexContentgt
• lt/complexTypegt
• ltcomplexType name"RoadType"gt
• ltcomplexContentgt
• ltextension base"gmlLineStringType"gt
• ltsequencegt

32
Query expressed by GML

• lt!--
• the query example
• --gt
• ltQueryModel gt
• ltgmlnamegtExamplelt/gmlnamegt
• ..
• ltqueryMembergt
• ltProvincegt
• ..
• lt/Provincegt
• lt/queryMembergt
• ltqueryMembergt
• ltRoadgt
•  
• lt/Roadgt
• lt/queryMembergt
• ltqueryMembergt
• ltG-pass-throughgt
• ..

33
Conclusion

• We are now focusing our activities on designing
  and implementing a new pictorial language in
  areas different from the geographical one. Our
  hope is to be able to specify relational queries
  in this way, without the end user needing to
  understand the intricacies of boolean logic or
  set theory.