VISCO: Bringing Visual Spatial Querying to Reality | of Michael Wessel

VISCO: Bringing Visual Spatial Querying to Reality Michael Wessel and Volker Haarslev University of Hamburg, Germany {mwessel, haarslev}@informatik.uni-hamburg.de VISCO Homepage: http://kogs-www.informatik.uni-hamburg.de/~mwessel/visco.html

• The Visual Language VISCO • The VISCO Prototype • Architecture • Graphical User Interface • Representing, Compiling and Executing Queries • Abstract Syntax Graph (ASG) • Optimizing Compiler (Petri Net Model)

• Example (Quicktime Movie) • Conclusion

Michael Wessel , September 98

VISCO: Vivid Spatial Constellations Basic Key Concepts •• Represent Representconstellations constellations(aggregates) (aggregates)of of geometric geometricobjects objects •• Describe Describeclasses classesofofpictures picturesthrough through pictures, represent spatial aspects pictures, represent spatial aspectsdirectly directly •• adequacy, adequacy,consistency, consistency,transparency transparency •• Extensions Extensions •• VSQL: VSQL:retrieve retrievefrom fromspatial spatialDB DB •• Geometric Geometricobjects objects •• Transformable Transformableagggregates agggregateswith with local coordinate system, polygons local coordinate system, polygons&& polylines, polylines,segments, segments,points points •• Guidance Guidanceofofinterpretation interpretationofofvisual visual aspects present in a VISCO definition aspects present in a VISCO definition •• Physical Physicalmetaphors metaphors •• Meta Metaobjects objects •• Expressive: Expressive:metric, metric,geometric geometricand and topologic relationships / constraints topologic relationships / constraints •• inside inside/ /contains, contains,disjoint, disjoint,intersects intersects

Some Quadrilaterals

55cm cm 5 cm

5 cm

Michael Wessel , September 98

VISCO: Concrete Shape, Arbitrary Shape, Vague Shape Degree of Vagueness can be seen (“Mental Animation”) 5 cm

5 cm 5 cm

5 cm 5 cm

5 cm

Michael Wessel , September 98

VISCO: Overview of Language Elements (Incomplete)

Marble

Nail

Origin

Constant Encl. Inner Encl.

Beam Antenna

Outer Encl.

=-Antenna

Inner Epsilon

Rubberband

Outer Epsilon

Lake Thematic Descriptor

10 ... 100 m Size Indicator

5 Transparency Film

At Most Constraint

Scaling

Arrow & Scale Michael Wessel , September 98

Example Query: How to Find a BBQ Place with VISCO Requirements for BBQ Place •• IfIfyou youdon’t don’town ownaacar, car,itit must mustbe beininthe thevicinity vicinityof ofaa subway subwaystation, station,we wedon’t don’t want to walk much more want to walk much more than thanapprox. approx.800 800meters meters •• We Wewould wouldlike liketotosit sitat ataa pond pond •• IfIfititisisaahot hotor orrainy rainyday, day,itit would wouldbe begood goodififthere there were weresome sometrees treesto to protect protectus us •• However, However,only onlyfoliage foliage trees are suitable trees are suitable

Distinguish Distinguishexplicit explicitand andimplicit implicit composite compositeobjects! objects!

VISCO Query

Pond Foliage Tree Subway Station

2 km

2 km

Michael Wessel , September 98

The VISCO Prototype: Logical Architecture Data Dictionary (Meta Data)

Graphical User Interface (GUI) Motivate Construct Validate Graphical Query Editor

Animator

Inspect Execution and Result Inspector

Normalizer (Inference Engine)

Optimizing Compiler

ASG (Abstract Syntax Graph) Repository

Spatial Database or GIS

Interface to Spatial DB External View

Currently not implemented: - Animator - Normalizer (Inference Engine)

Michael Wessel , September 98

VISCO GUI: The Graphical Query Editor Buttons Buttons

Query Query Editor Editor Working Working Area Area Infos Infos

Query Query Construction Construction History History

Objects Objects

Operators Operators

Options Options Command Command Line Line Michael Wessel , September 98

Representing Queries Abstract Syntax Graph (ASG)

Simplified Query

•• Directed Directedmulti-hypergraph multi-hypergraphwith with attributed attributededges edges •• Properties Properties(unary) (unary) •• “has-thematic(x)” “has-thematic(x)” •• Edges Edges(binary) (binary) •• “direct-part-of(p,l)” “direct-part-of(p,l)” •• Hyperedges Hyperedges(tenary, (tenary,...) ...) •• “intersection-point-of “intersection-point-of (p,l1,l2)” (p,l1,l2)”

•• ASG ASGmaintained maintainedby byoperator operator applications provided applications providedby bythe the repository repositorymodule module •• Preconditions Preconditions

•• Graphical Graphicalquery queryeditor editormaps maps user’s interactions to internal user’s interactions to internal ASG ASGoperator operatorapplications applications •• History Historyofofoperator operatorapplications applications

Road Lake

Simplified ASG Lake

has-thematic

L

Road

intersects

S1

S2

S3

P1

P2

P3

R

P4

P5

direct-part-of Michael Wessel , September 98

Compiling & Executing Queries Plan Generation

Compiler: Petri Net Model

•• Use UseASG ASGto toconstruct constructan anexecution execution plan plan

D1

•• Order Orderofofsequence sequenceofofnode nodeprocessing processing (currently, simple Backtracking) (currently, simple Backtracking) •• Binary Binaryinverse inverseconstraints: constraints:multiple multiple plans become possible, potentially plans become possible, potentiallyn! n! •• Optimizer: Optimizer:find findbest bestplan planby byvaluation valuation

D2

E1

E2

•• Query Queryobjects objects •• Searchable, Searchable,use useindexing, indexing,especially especially spatial indexing spatial indexing

•• Universal Universalobjects objects •• Must Mustbe beconstructed constructed(components (componentsor or operator arguments already operator arguments already instantiated) instantiated)

Lake

Road D1=defer E1 D2=defer E2 E1=intersects(Lake,Road) E2=intersects(Road,Lake)

•• Geometric Geometricobjects objects&&enclosures enclosures •• Spatial Spatialselection selectionpossible possible •• e.g. e.g.use useR-Tree R-Tree

Possible D1 - Lake - E2 - Road Plans: D2 - Road - E1 - Lake Michael Wessel , September 98

Current State of Work, Conclusion & Future Work • VISCO prototype places additional restrictions on the (query) language VISCO • VISCO prototype places additional restrictions on the (query) language VISCO

• E.g., transformations must be uniquely determinable • E.g., transformations must be uniquely determinable • E.g., for an universal arbitrary scalable and rotatable transparency film at least 3 • non-collinear E.g., for an universal arbitrary and rotatable transparency film at least 3 instantiatable nailsscalable are needed non-collinear instantiatable nails are needed

• Optimizer: use more knowledge • Optimizer: use more knowledge

• Much more heuristics need to be included • Much more heuristics need to be included • Exploit database statistics as well as properties of spatial relations • Exploit database statistics as well as properties of spatial relations

• Missing components / modules • Missing components / modules

• Animator • Animator • Normalizer / Inference Engine • Normalizer / Inference Engine • Derive additional constraints only implicitly present, make them available for the • compiler; Derive additional constraints reuse only implicitly make them available for the query subsumption, of querypresent, results (refine); query normalization compiler; query subsumption, reuse of query results (refine); query normalization • Use a “real” GIS / spatial DB • Use a “real” GIS / spatial DB

• VISCO GUI • VISCO GUI

• Currently, too abstract for end users • Currently, too abstract for end users • Not evaluated yet • Not evaluated yet

• However, the usefulness of the visual language VISCO has been proven • However, the usefulness of the visual language VISCO has been proven Michael Wessel , September 98