Towards Infusing Giovanni with a Semantic and Provenance Aware Visualization
System
Intern: Nicholas Del Rio
[email protected]
Mentor: Dr. Gregory Leptoukh [email protected]
Abstract
The visualization Knowledge (VisKo) framework dynamically links data with visualization
processes, provided characteristics about data and requested visualization targets from
users (i.e., time series plots, raster and contour maps). Early integration efforts between
VisKo and Giovanni, a fully operational online data analysis system, revealed that VisKo
can satisfy Giovanni visualization requirements and thus serve as a visualization
delegate. In particular, VisKo provides the link between Giovanni data and visualization
services at conceptual (i.e., ontological) levels which can be mapped to implementation
(i.e., services) levels, facilitating an adaptable environment for new visualization
scenarios.
Method
Results
In order for VisKo to visualize data on behalf of Giovanni, we need to understand:
• What kinds of data are supported and how they are encoded (i.e., format)
• What XML provenance elements supported by Giovanni can serve as sources to
populate the characterizations of data required by VisKo
• What visualizations are expected by Giovanni for different kinds of data
We were able to identify Giovanni data formats and semantic types from by examining
Giovanni provenance lineage-steps, for example:
• <output type="netCDF”>  PMLP:Format
• <input- name="D1">MYD04_L2.051:AOD0470corr-l:medn>  PMLP:Information
Provided the above information, we can populate VisKo with knowledge about:
• The mappings between Giovanni data characteristics and visualization processes
• The set of NCL services (i.e., plotters) that can satisfy Giovanni visualization criteria
Giovanni Background
Giovanni-VisKo Model
Giovanni is a Web-based application developed by GES DISC that provides a simple and
intuitive way to visualize, analyze, and access vast amounts of Earth science remote
sensing data without having to download the data. The Giovanni visualization module is
dependent upon a set of visualization services supported by third party rendering
packages such as NCAR Command Language (NCL).
Giovanni:
•
•
Consequently, the Giovanni visualization module may not be easily adapted to new
visualization scenarios because of:
• Hard coded relationships between data and visualization services
• Regards for data as holistic entities (i.e., without much internal structure)
• Consolidation of entire visualization processes into single “black-box” services
We encoded this information in PML, which was used by VisKo to identify appropriate
NCL pipelines that visualize brightness temperature as contour and raster maps and
aerosol time series as XY plots.
Forwards user visualization requests to VisKo
Forwards XML provenance describing the processing associated with data requested
by users
VisKo in turn:
• Translates Giovanni XML provenance to PML
• Generates requested visualizations, leveraging the translated PML
• Returns visualization along with data + visualization PML
Currently, the Giovanni visualization module is not fully aware of:
• The conceptual relationships between data and visualization processes
• The structure and semantics of data
• The visualization process as sets of reusable service chains known as pipelines
University of Texas at El Paso
NASA GES DISC
Aerosol Time Series Plot
Brightness Temperature Contour and Raster Maps
We developed an extractor service that is responsible for translating Giovanni XML
provenance into PML for VisKo ingestion. This PML bridges Giovanni and VisKo.
Giovanni PML
Response
Giovanni
MAPPS Data Store
Response
Data Processing
Provenance
Visualization
Provenance
(hasView ?DATA xyPlot)
(hasBinding height 300px)
The example to the right represents PML describing the
processing of an aerosol time series dataset fetched from the
MAPPS data store and filtered by HTTPSubsetter.
(hasBinding width 300px)
(hasBinding line-colors red,yellow)
(hasBinding line-smoothness 10)
Screenshot of Giovanni interface for aerosol data selection along with associated time series plot
The provenance generated by Giovanni is regarded as data
processing provenance; it describes processing such as
interpolating, filtering, and adjusting or correcting.
Giovanni
Search [MAPPS}
Data processing serves to corral data into forms suitable for
analysis (e.g., visualization) and therefore differs from the
transformations associated with visualization, which aim to
translate data into graphics.
Request
(AND
Data Processing Provenance
Giovanni
HTTPSubsetter
VisKo
Visualization KB
VisKo Background
Visualization Provenance
Interaction between users, Giovanni, and VisKo
VisKo is a semantic aware visualization framework that leverages data characteristics to
match up data with visualization processes; users may optionally provide VisKo with plot
specifications to restrict the set of generated visualizations.
VisKo:
• Searches a knowledge base containing descriptions of toolkit rendering capabilities to
identify pipelines of visualization-related services that it can execute
• Captures provenance associated with pipeline execution in Proof Markup Language
(PML)
VisKo relies on:
• PMLP:Format and PMLP:Information (i.e., semantic type) for data characterizations
• ESIP data-type ontology for characterizations of views (i.e. plot geometries)
References
Acker, J. G and Leptoukh , G. Online Analysis Enhances Use of NASA Earth Science Data, Eos
Trans. AGU, 88(2), December 2007
McGuinness, D and Pinheiro da Silva, P. Explaining Answers from the Semantic Web: The
Inference Web Approach. Journal of Web Semantics. Vol.1 No.4., pages 397-413, October 2004.
Del Rio, N and Pinheiro da Silva, P. Leveraging an ESIP Data-Type Ontology to Support
Visualization. AGU, Poster, December 2010
PMLP:netCDF
PMLP:Aerosol
(hasBinding line-colors red,yellow)
Portable
Network
Graphic
Portable
Document
Format
•
Further characterize data beyond type and format (i.e., continuous, nominal, etc.)
•
Understand how these data characteristics can be used to configure visualization
geometries such as line smoothness and color gradients
•
Configure VisKo to leverage more data processing provenance when identifying
pipelines and parameter settings, rather than relying only on PMLP:Information and
PMLP:Format
•
Develop viewers that display visualizations along with provenance in ways that
provide users with useful balances of context needed to understand the plot but
with a level of conciseness that does not impair the readability
http://nasa…
(hasBinding line-smoothness 10)
NCL
netCDF
Reader
NCL
gsn_csm_xy2
GhostScript
PS2PDF
PostScript
VisKo PML
PMLP:hasFormat
(hasBinding width 300px)
GhostScript
PDF2PNG
Visualization PML contains both the plotting steps (e.g., NCL xy
Plotter) and any arguments passed to xyPlotter (not shown).
Future Work
(hasView ?DATA xyPlot)
(hasBinding height 300px)
Visualization PML augments Giovanni data processing
provenance to provide complete descriptions of how data was
gathered, filtered and finally visualized.
NCL
xyPlotter
Del Rio, N and Pinheiro da Siva, P. Visualization Knowledge (VisKo) Website.
http://trust.utep.edu/visko
Data Characterization
Plot Specification
(AND
VisKo generates PML describing the execution of visualization
pipelines (i.e., visualization provenance).
NCL Data
Model
Synthesized Visualization Pipeline
Pipeline
Search
VisKo pipeline search using SPAQL queries
Visualization KB