IEHIAS spatial visualisation toolbox

The text on this page is taken from an equivalent page of the IEHIAS-project.

The visualisation tool is used as a front-end to analyse data in the IEHIA computation system. Its purpose is to display the data in a graphical format to enable the user to interpret results of a model spatially. As visualisation is the primary function of this tool, there is a strong emphasis on the re-symbolisation (styling) of the data. This enables the user to control the appearance of the outputted data to clearly visualise results.

Purpose

To enable spatial visualisation of data outputs from environmental models in an online environment.

Boundaries

The visualisation tool is capable of displaying all fields within a model providing they can be visualised spatially. The limitation with respect to spatial resolution are constrained within the parameters of the computer hardware.

Input

All inputs are text based tabular data that is utilised and interpreted by the open source software.

The primary database for visualisation is: PostgreSQL and is a georeferenced tabular format.

(All model and scenario results in HEIMTSA are stored in a georeferenced database – provided by the work package 5.2 (HEIMTSA D 1.3.3 2007))

A temporary dataset is also generated (for each chain in the model) in the form of a JSON format for use in GENERATING GRAPHICAL data in the visualisation tool.

Output

Within the visualisation tool the following can be output: MAPS, CHARTS and FEATURE INFORMATION.

Interactive MAP outputs are generated using the Web Map Service (WMS) are displayed in a PNG format (PNG is chosen as it provides a crisper cleaner image without the tiling effect associate with its jpeg counterpart). The automatic georeferencing of an added layer and the assigning of a related coordinate system allows for the png file to be queried.

FEATURE INFORMATION is displayed in a tabular format upon clicking on an item within the map. As the map is georferenced, based on the x & y coordinates of the query an html response is generated to call the relevant information from geoserver.

Graphical CHART-based outputs are generated using functionalities within “ext”. The data used for creating these charts are held temporarily in a JSON store. These charts are visualised in a floating window and can be exported as a JPEG or PNG.

Description of processes modelled and of technical details

Management of the model

The Visualisation Tool was developed at the University of Exeter, UK alongside the Joint Research Centre of the European Commission (JRC)

Unit responsible for running and maintenance

The visualisation tool and its subsequent components are hosted at the Joint Research Centre of the European Commission.

Contact persons

• Programmer of visualisation tool: Dr Barry Evans, Email: be208@exeter.ac.uk
• Under the Scientific coordination of: Dr Clive Sabel, Email: c.sabel@exeter.ac.uk
• Administrator and Maintenance of visualisation tool: Vittorio Reina. Email: Vittorio.REINA@ec.europa.eu

Time required for a typical run

This does not strickly apply – it is an interactive online tool. In terms of visualisation the “run time” required to visualise data is broken up into 6 basic parts.

1. Transferring data from raw model output into PostGIS database
2. Generating JSON formatted data (used for rendering chart data later as deemed a more efficient format for this process)
3. Serving/publishing the data into Geoserver
4. Open up webpage
5. Call in and render MAP from Geoeserver
6. Resymbolise MAP with basic thematic styling

The typical time required to complete these steps on a localised system is typically around 10 seconds. The rendering on non-localised systems will be dependent on the internet connection.

Operating system

The tool operates interactively within a web browser, using open source software and is thus operating system independant.

Database type

The database used in this tool is PostgreSQL with PostGIS spatial extension

Portability

NO: The system is designed to be set up and hosted on one system. The visualisation tool can be accessed on any system with “java runtime environment” enabled web browser such as “Firefox, Internet explorer, and others”. It can also be accessed on multiple locations simultaneously.

Software needed to run model (server side)

• PostGIS
• PostgreSQL
• Geoserver
• PHP
• cURL
• Java
• Javascript
• Ext
• GeoExt
• Openlayers

Software needed to run model (Client side)

Java runtime environment

Web browser

Hardware platform

Not relevant – any standard server specification will suffice, dependant on simultaneous useage.

Programming languages and functions

• HTML
• CSS
• Javascript
• Java
• Ajax
• PHP

Degree of mastery

The tool is designed to be used by non-expert and expert users alike. It is set up so that just by one click on the button associated with the layer you are querying it will be displayed automatically within the visualisation tool. There are options within this toolbox for navigating your way around the data, re-styling, and generating chart information and these have been set up to be intuitive and thus easy to use.

Developed by/support

Developed by Dr Barry Evans. Support is offered via an online help system within the tool.

Can modify/reprogram

YES: The program has been built using a “bottom-up” approach and additions to the visualisation tool are possible. The software packages used (Geoserver, GeoEXT, PostGIS, etc) are constantly evolving with inputs and ideas from the Open source software communities associated with them enabling more features and potential expansion of the software in future.

Can transport to an alternate platform

YES: Although the software is designed to be hosted at one location it can be migrated to other systems if needed. As it is comprised of a variety of open source programs a basic setup procedure must be followed.

Cost of using the model

As only Open Source based software packages were used there is no continual licensing fee to be paid to run the software. All costs therefore relate to the cost of maintaining the server and hosting. Extra costs would be involved for expansion of the model if required

Intellectual property rights

University of Exeter

Owned by

Dr Clive Sabel, University of Exeter

Open source tool

Expansion/modification is possible

Rationale

This tool assumes no prior experience within Geographical Information Systems and is thus easy to utilise for basic users. From a single click data is geo-referenced, styled and displayed in a map based format for the user to immediate visualise results. Using the basic functionalities the user can customise the appearance of their data and obtain further attribute information. The “Chart” function from EXT allows for quick rendering of information associated with a layer within the visualisation tool.

What would be the task of visualising data using one “commercial” based product is shared between a variety of “open source” products. This increases the computational loading and reduces performance. The level of functionality available in the visualisation toolbox is basic and does not (currently) allow for more advance functions such as aggregation, regionalisation, linked window brushing and spatial analysis.

This tool was developed solely using Open source software and as such there is no ongoing licensing fee to pay therefore greatly reducing running costs. Although it is based on non-commercial software the capabilities of the packages and methods used enable some functionality akin to that of commercial software providers. The open source software used for this model is already well established and regarded as being a powerful tool in the field of spatially visualising data.

The toolbox allows for visualisation of quantitative uncertainty data either in the main map viewer or within an external window.

See also

• Geoserver
• PostGIS
• PostgreSOL
• GeoExt
• Ext
• Openlayers