User Interfaces and Spatial Query Languages

Example query

• "display a topographic map of Austria"
• "remove all third-class roads"
• "differentiate between places with populations larger/smaller than 10,000"
• "where is Innsbruck?"
• "change color of railways to green"
• "what is this ?"

Requirements for Query Languages in General

• deal with retrieval and presentation
• support application semantics
• multiple roles of QL
  - ad hoc queries
  - programming
  - data exchange
  - manipulation
  
  
• language design
  - user oriented vs.
  - data model oriented
  
  
• language divisions
  - database perspective (QL, DML, DDL) vs.
  - natural language perspective (users)

+ Requirements for Visual QL

• graphical vs. tabular presentation
• specifying graphical presentations
• interferential i/o
• gestural input

+ Requirements for Geographic QL

• support spatial concepts
• importance and variance of user concepts (compared to standard applications)
• support spatial relationships
  - topology
  - approximate metrics
  
  
• support two retrieval modes
  - attribute-based
  - location-based
  
  
• complexity of data presentation
  - high quality graphics
  - context
  - multiple views
  - changes in presentation can require DB access

Spatial SQLs

• support for spatial and attribute-based access
• engrained tabular data model
• various extension strategies:
  - modify syntax, e.g. additional clauses (WITH LOCATION, AT, ON)
  - comply with standard and define display environment

Critique

• semantics:
  - spatial concepts are incompatible with table concept
  - spatial relationships lack formal semantics
  
  
• syntax: 1d language for 2d, 3d space
• graphics: weak presentation components
• human factors: low usability.
• useful for low-level retrieval, as language to exchange data between different geographic databases

Future Directions in Spatial Query Languages

• formalize spatial concepts (independently of data models)
• toward full interaction languages
• displays beyond static maps
• iconic SQLs ?
• multi-modal interfaces
• multi-cultural interfaces
  

Last updated on July 26, 1996.