1. Schema translation and data quality Sven Schade
Bilateral Research Workshop: INPE and IfGI
GIScience for Dynamic Environmental Sensors
March, 11th, 2009

2. Overview of the talk My recent work Current conclusions
/introduction
Overview of the talk
My recent work
Current conclusions
Relations to workshop theme
Outlook

3. What is the motivation for my work?
/recent work
What is the motivation for my work?
Increased demand for spatial data sharing
Translations are frequently required
Scientific view:
Specifying intendet interpretations of data model expressions
Ongoing research in using these for translation
Practical view:
Providing national data sets in internationally harmonised models
Provide according metadata

4. Which problem does this work address?
/recent work
Which problem does this work address?
Natural language descriptions of data model expressions

5. Which problem does this work address?
/recent work
Which problem does this work address?
Natural language descriptions of data model expressions
Use of a common language cannot be assumed
Definitions include degrees of freedom
Potential translations not computer-tractable
Data model descriptions have to be provided in a form that permits
Judgement if a translation can be performed
Identification of the consequences
Computer-tractable translation

6. What is a practical example?
/recent work
What is a practical example?
If I:
Know what the data models capture as road width
, and
Know about used units and measures
Then I:
Can infer possible translations and their effects
Can provide quality metadata for translated data sets
Effect: overestoimation!

7. What is the approach and design of research?
/recent work/approach
What is the approach and design of research?
Semantic Reference Frame for Geospatial data
Algebraic Theory for Shifting between Frames
grounds
Conceptual Level
Implementation: Logic Program
Implementation:
Functional Program
Formal Level
Research
Prototype
Proof of Concept

8. What are the conclusions of this work?
Focused on object-models of geospatial phenomena
Improved support in translation on attribute level
Metric and ordinal attributes
Most attributes are categorical
Current means can account for imprecision in:
Intended interpretation
Measurement
Translation
We only understand small parts of challenges regarding nominals
But we have a good impression on current possibilities

9. What are the next steps? … actually that is a step back!
It is easier to describe (physical) measures than complex objects.
Measurement-based approach (for example inferring land cover from raw satallite imagery)
First: field-models for geospatial phenomena
Second: object-models for geospatial phenomena

10. What about an illustration?
/relation to workshop theme
What about an illustration?
Here is the obvious one:
field- and object-based
Models of the Environment
field-based
Source: Gilberto Câmara (INPE)
Requires translation
(+ quality information)
Provide input to
Semantics
i.e. clarify intended
interpretations
Sensors/
Sensor Web
Syntax and Access
(OGC: SWE)

11. But what about change? Geospatial Change Object Models Objects
/relation to workshop theme
But what about change?
Geospatial
Objects
Change
Event(s)
Object Models
Change
of identity
Basis for
characterising
Source: Carlos Nobre (INPE)
(new?)
Physical Qualities
e.g. mass, length,
temperature
Time
Continuous
change
Sensors

12. Which questions should be answered next?
/outlook
Which questions should be answered next?
What is required to sharpen the last illustration?
Do ontologies only support correct input for models of change?
Should change detection use ontologies?
What are the limits of computer-tractable translation?
How important is the role of uncertainty modelling considering the workshop scenarios?
Which types of uncertainty should be considered?
Which data quality parameters are important (lineage etc.)?

13. /end
Thank you very much!
INPE and IfGI Delegation

14. /details
Annotation

15. Relations between data models
/details
Relations between data models

16. User roles in ontology-driven translation
/details
User roles in ontology-driven translation

17. Activity diagram of demonstrator
/details
Activity diagram of demonstrator

18. /details
GUI view

19. Categories of Imperfection
/details
Categories of Imperfection

20. Categories of Incompleteness
/details
Categories of Incompleteness