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Spatial Data Integration

In our digital age and in an increasingly complex and rapidly changing world the administration of the natural and built environment is primarily based on spatial data in its widest sense. The data are used for analysing, visualizing, controlling and monitoring the impact of human activities and the climate change with the associated cross-border hazards and provide the basis for a better risk assessment, and situation awareness.

The spatial data product integration plays a major role to meet this challenges and create new added value products out of the existing sources.

Further information about data products can be found here: GDI > Metadata and Data > Spatial Data

Introduction

To map specific real world scenarios we need to combine different spatial data products. Each data product is providing one or more information layers, which will often need to view simultaneous.

A general definition of spatial data integration in this context reads as follows:

Spatial data integration means the merging of information from different static and dynamic data sources to a structured unit.

The present modeling and presentation of these structured units is based on static methods. In order to visualise and link dynamic scenarios graphically in a user-friendly and harmonised way, we need well designed representation techniques, which allow both elementary and complex statements and visual perception of time based changes.

Interoperability Issues

Interoperability is a crucial element for efficient integration and presentation of multi-sourced spatial data in theme- and cross-border applications.

In this context interoperability means the possibility for spatial dataset to be combined, and for services to interact, without repetitive manual intervention, in such a way that the result is coherent and the added value of the datasets and services is enhanced (inspire.ec.europa.eu).

Further information about the interoperability of data products can be found here: Spatial Data Infrastructure > Interoperability

An important role plays the interoperability while simultaneously presenting data products in GIS and similar systems. In the following questions and problems concerning to the integration and interaction of the portrayal of data products are listed. New issues will be added if are identified.

Data Clashes
Multiple Feature Instances This issue is caused by the inclusion of the same real-world phenomenon in multiple product specification application schemas. This includes instances of the same feature which may have different attributes in different domains.
Harmonising Portrayal
Order of Significant Features Make sure that less important features in one data product are not displayed than more important features in another data product.
Hierarchy of Data
This issue cover the display setting priorities of data between different data products.
Updates
Management of Updates The interoperability catalogue must be designed in such a manner, that the need for updating is minimal when the feature catalogue or product specification is updated.
Combine Data Quality Measures
Each dataset may have its own quality metadata. What quality measure should be used when different products are simultaneously active on the graphical display?

Spatial Data Scenarios

Spatial data scenarios describe how data products interact with each other. The interaction depends on the respective use case, type of user and equipment.

  • Overlay: Data that just sits on top of each other.
  • Interleaving: Data from different data products need to work with each other.
  • Replacement: Data which are certified to replace parts of another data product.
  • Suppression: Data that are designed to suppress another data product

Spatial Data Integration Process

The figure below shows the main components to realise the spatial data integration process.


Figure 1: The spatial data integration process

In general, the spatial data integration process is a function-based portrayal mechanism. Instances of features are portrayed based on portrayal functions, which make use use of geometry and attribute information. The relationship between the feature instances, attributes and the underlying spatial geometry is specified in a product specification.

Based on a real world scenario a use case will be described. A use case illustrate all dependencies and relationships between an actor and a system, to achieve a business goal. The description is independent from a specific technical solution.

The Interoperability Catalogue is a machine-readable file or collection of files describing how a system or a application combine data products conforming to different product specifications for display purposes.

A machine-readable Portrayal Catalogue contains functions which map features defined according to the General Feature Model (GFM) into drawing instructions and symbolisation. It contains furthermore colour definitions, line styles and display mechanism e.g. display groups.

The output of the Portrayal Engine are drawing instructions transformed from the product specification based feature data.

Drawing Instructions link the feature type to a symbol reference. Available are geometry depended instructions (e.g. distance, rotation and scaling) and geometry independent instructions (e.g. display groups, drawing order). Drawing instructions are intermediate data used by the rendering engine to produce the final display.

Example: e-Navigation Concept

e-Navigation stands for enhanced-Navigation and is a major initiative off the International Maritime Organization (IMO) to harmonise and enhance navigation systems. It is expected to have a significant impact on the future of marine navigation.

After the definition of the IMO are data a central part of the e-Navigation concept:

"e-Navigation is the harmonised collection, integration, exchange, presentation and analysis of maritime information onboard and ashore by electronic means to enhance berth to berth navigation and related services, for safety and security at sea and protection of the marine environment”

In order to successfully handle these challenges and make e-Navigation reality, we need a common data structure to harmonise and standardise all the different both static and dynamic data types and services. A selection of relevant data types can be found below:

  • Onboad
    • Sensor Data
    • Communication Data
    • Navigation Data
  • Ashore
    • Vessel Traffic Information (e.g. AIS)
    • Infrastructure Data (Maritime Data)
    • Communication Data
  • Surrounding/Environment
    • Oceanography(Tidal Range, Currents, Salinitet, Waves...)
    • Meteorology (Wind, Temperature...)

The stakeholders agreed that the already established IHO concept of a "Universal Hydrographic Data Model" (UHDM) known as S-100 will be the basis of the "Common Maritime Data Structure" (CMDS). S-100 is based on the ISO 19100 series of geographic standard which is well established in the GIS world and connects the maritime with other spatial data.

Further information about the UHDM can be found here: IHO > ENCs, ECDIS & S-100

The growth of data streams does not automatically mean more information, better knowledge and, as a result a more efficient decision making. There is a risk of "data overload". The "data overload" actually results in less information available to the mariner and not in more.
To avoid this situation, the different data streams need to be integrated and prepared for use in a situational centric e-Navigation display to ensure they reach the mariner as an integrated layer with meaningful and/or new information.

Examples for data integration to generate new values out of the data:

  • Real time water level information needs to be combined with static shore information
  • Dynamic ship weather-routing optimisation, improving energy efficiency, time-saving, minimize voyage distance and enhance speed performance

The figure below illustrates a possible data integration in the e-Navigation concept.


Figure 2: Possible e-Navigation Data Integration

Further information about the e-navigation concept and current activities can be found here: e-navigation.net

Case Studies and Documents

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