- Open Access
A simple method for serving Web hypermaps with dynamic database drill-down
© Boulos et al; licensee BioMed Central Ltd. 2002
- Received: 11 July 2002
- Accepted: 9 August 2002
- Published: 9 August 2002
HealthCyberMap http://healthcybermap.semanticweb.org aims at mapping parts of health information cyberspace in novel ways to deliver a semantically superior user experience. This is achieved through "intelligent" categorisation and interactive hypermedia visualisation of health resources using metadata, clinical codes and GIS. HealthCyberMap is an ArcView 3.1 project. WebView, the Internet extension to ArcView, publishes HealthCyberMap ArcView Views as Web client-side imagemaps. The basic WebView set-up does not support any GIS database connection, and published Web maps become disconnected from the original project. A dedicated Internet map server would be the best way to serve HealthCyberMap database-driven interactive Web maps, but is an expensive and complex solution to acquire, run and maintain. This paper describes HealthCyberMap simple, low-cost method for "patching" WebView to serve hypermaps with dynamic database drill-down functionality on the Web.
The proposed solution is currently used for publishing HealthCyberMap GIS-generated navigational information maps on the Web while maintaining their links with the underlying resource metadata base.
The authors believe their map serving approach as adopted in HealthCyberMap has been very successful, especially in cases when only map attribute data change without a corresponding effect on map appearance. It should be also possible to use the same solution to publish other interactive GIS-driven maps on the Web, e.g., maps of real world health problems.
- Joint Photographic Expert Group
- Zoom Level
- Object Layer
- Late Update
- Graphic Interchange Format
HCM features a novel and unconventional use of GIS to map conceptual spaces occupied by collections of medical/health information resources. Besides mapping the geographical provenance of these resources, HCM also collects and maps some non-geographical and semantic aspects of these resources (e.g., clinical subject or topic) using suitable metaphors like human body organs/systems maps. The resultant maps are conceptual information space maps used as a visual navigational aid for browsing mapped resources.
From desktop GIS to the Web
Old  describes two main steps when using GIS to map conceptual information spaces (as in HCM):
– First, information in non-spatial data is spatialised, analysed, browsed, and processed using (desktop) GIS and cartographic methods; then
– The resultant information maps and their connections to the underlying data are shared on the Web as sensitive clickable maps for Internet browsing and navigation of mapped spaces.
This paper focuses on the second step in this process. Two main options exist to deliver this step:
– Dynamic publishing to the Web using a dedicated Internet map server that maintains a live connection with the underlying GIS project/database; or
– Publishing a static snapshot of the project (representing the project's maps and underlying data at time of publishing) as clickable client-side imagemaps using tools like ImageMapper from alta4, Germany http://www.alta4.com/eng/products_e/im/im30/index_e.htm and WebView from Zebris, Germany http://www.zebris.com/english/main_webview.htm. (HCM method is a modified version of this option to partially compensate for its limitations as shall be described below.)
Dedicated internet map server solutions for serving maps with dynamic database drill-down functionality
ESRI Internet Map Server allows users to easily look up places on the map, e.g., by typing the names of the places they want to locate on the map. However, typing errors and disagreement about correct spelling of map features can severely limit the usefulness of such feature .
Costs associated with dedicated internet map servers
Unfortunately, all these excellent features of dedicated Internet map server solutions do come at a cost:
- Price (several thousands of US dollars);
- Expertise is required to install, customise and manage the Internet map server;
- Full access to the hosting Web server is required to install and manage software components (not always possible with mainstream (cheap) shared virtual hosting packages offered by most Web Hosting Providers; for example, HCM current Web hosting package does not allow full access to the hosting server to install extra software); and
- ESRI MapCafe Java applet might be slow to download (depending on speed of client's Internet connection).
This paper describes a simple, low-cost way that has been developed for HCM to serve hypermaps with dynamic database drill-down functionality (dynamic database links) without the need for a dedicated Internet Map Server.
HCM has been developed as an ArcView GIS project and features GIS-driven spatialisation based on an underlying resource metadata base where ICD-9-CM codes (WHO International Classification of Diseases, ninth revision, US Clinical Modification) describing the topics of mapped resources are stored alongside other useful information about theses resources, including their geographic provenance and Web addresses . We used ESRI ArcView GIS Version 3.1 for Windows http://www.esri.com. WebView 1.1, the Internet extension to ArcView GIS, was then used to translate HCM Views (maps) from ArcView to the Web in the form of client-side imagemaps in JPEG format. The authors also used another ArcView extension in HCM project, namely BodyViewer v2.1 for ICD-9 codes from GeoHealth, Inc. to generate HCM human body maps (see below).
– Detail and overview maps (Figure 1 above). The detail map displays all visible themes of the active view in the chosen scales; it only displays part (one tile) of the whole view area at a time. The overview map displays the overview themes of the whole area at once in miniature form. A red positional rectangle moves over the overview map to show the location of the area currently displayed in the detail map. Users can also navigate to a different area in the detail map by clicking in the overview map.
– Panning in the detail map is also possible using four arrow buttons for the four directions (up, down, right, left).
– Legend for map contents.
– Scale bar.
– WebView offers three-way hotspots with two-way clicks depending on which toolbar button (Identify button with a blue 'i' icon or HotLink button with a yellow spark icon) is selected when the user clicks a map object:
– attribute information can be displayed on mouse over (map feature ToolTip, e.g., in HCM maps, country name or body organ/system name);
– other attribute information can be displayed on mouse click while the Identify button is selected, e.g., to display more country information in a message box based on one or more attribute fields (Figure 23 below); and
- mouse clicks while the HotLink button is selected can be associated with an image, video, sound file, Web page or email address. (In HCM, we associated them with database query pages to be executed on HCM Web server.)
- Zoom in and zoom out in the detail map (up to three zoom levels in WebView 1.1).
- Up to five themes can be selected as interactive layers for each of the three zoom levels; attributes of these themes can be associated with the different mouse events outlined above (Figure 5). Different themes (layers) can be associated with the different zoom levels. This allows for different map contents and detail at different zoom levels (scales). This zooming strategy is called static stepped zooming.
Although it saves users the trouble of setting-up and running more complex Internet Map Server software while offering similar user interface features, the basic WebView set-up does not support any real GIS database drill-down functionality (the generated maps cannot communicate with the corresponding underlying databases). Moreover, projects published by WebView on the Web are uncoupled or disconnected from the original corresponding projects in ArcView.
"Patching" the basic WebView set-up
HCM metadata base (based on Dublin Core metadata set)
Candidate Internet resources are hand-selected (to ensure quality). Their attributes, including Web address and ICD-9-CM codes representing their subjects, are compiled in HCM metadata base based on the Dublin Core (DC – http://www.dublincore.org/) metadata set scheme with HCM own extensions for resource quality and geographical provenance.
HCM allows for three DC subject fields per resource record permitting up to three ICD-9-CM codes to be used to unambiguously describe the topic(s) of each selected resource.
Using ArcView's BodyViewer extension
BodyViewer is an ArcView GIS extension from GeoHealth, Inc. http://www.geohealth.com/ that combines the power of GIS with computerised body organ system diagrams. It lets users see where their ICD-coded healthcare data (medical/health Internet resources in our case) map onto the human body based on the body region(s) they cover .
We used this extension to generate the human body topical maps in HCM. These maps allow the navigation of resources by body location/system according to ICD-9-CM. In BodyViewer human body maps, map symbols are miniature simplified drawings or icons of the different body organs and systems. They act as visual labels to the different resource categories that have been classified and mapped according to their DC subject fields (ICD-9 codes). These icons (on the corresponding Web hypermaps) are linked to respective ASP query pages that are executed on HCM Web server to retrieve the appropriate resources based on the ICD-9 codes represented by the clicked icon. For example, if the cardiovascular icon is clicked, a query will be launched to retrieve resources with cardiovascular ICD-9 codes. Our bibliographic/cybergraphic use of this extension to map ICD-coded medical/health Internet resources is the first of its kind and was never suggested in BodyViewer documentation by GeoHealth, Inc. (the manufacturer of BodyViewer).
HCM World map in ArcView
HCM Web Interface
(Only components generated using the "patched" WebView method are described below.)
Clicking a human body icon on these maps triggers a server-side dynamic query. This is for example the pre-formulated SQL query that currently runs on HCM server in real-time to retrieve resources having E codes (codes for External Causes of Injury and Poisoning) in any of their DC subject fields http://healthcybermap.semanticweb.org/bodyviewer/e-codes.asp – see Example ASP page from HCM in "Additional file" for full code of this page):
sql = "SELECT hcm. [dc:Creator], hcm. [dc:Title],
hcm. [dc:Subject:1], hcm. [dc:Subject:2], hcm. [dc:Subject:3],
hcm. [dc:Description], hcm. [dc:Publisher], hcm. [dc:Date],
hcm. [dc:Type], hcm. [dc:Identifier], hcm. [dc:Language],
hcm. [dc:Coverage], hcm. [hcm:Location:city],
hcm. [hcm:Location:country], hcm. [hcm:Quality], hcm. [hcm:Comment] FROM hcm WHERE (((hcm. [dc:Subject:1]) Like 'E%')) OR (((hcm. [dc:Subject:2]) Like 'E%')) OR (((hcm. [dc:Subject:3]) Like 'E%'))"
All three DC subject fields in each resource record are searched for matching ICD-9-CM codes.
HCM World Map Web interface is available on the Web at the following address: http://healthcybermap.semanticweb.org/world_map/ (Figures 1 and 23). The maps can be used to browse Web resources by country of provenance.
Maintenance of HCM Web maps
Since WebView does not allow the dynamic generation of Web maps from ArcView, some of HCM Web maps will ultimately need to be manually regenerated using WebView when the underlying data change if this change has implications on the maps' appearance. In cases when only map attribute data change without a corresponding effect on map appearance, e.g., updating the address of a Web resource in the metadata base, nothing needs to be done; the same ASP query pages (unmodified) will retrieve the latest updates. HCM GIS-generated Web maps can be grouped into:
– Choropleth maps that need to be regenerated when the underlying data are updated, e.g., the BodyViewer maps as the colour shades of the various body organ systems in these maps reflect the number of resources associated with them, and so will change whenever the database is updated (resources added and/or deleted). In this case, the Web maps must recreated in ArcView using WebView then uploaded to the Web server to replace older ones. Associated query pages need not be changed.
– Chorochromatic maps that don't usually need to be updated, e.g., the world maps. Whenever new resources are added (or existing ones updated/deleted), they will automatically appear (or disappear) in the query results when the corresponding countries on the map are clicked. There is no need to change the map as long as the addresses of the dynamic ASP query pages on HCM server don't change (e.g., http://healthcybermap.semanticweb.org/canada.asp). The only reason to regenerate these maps would be if some of their underlying attribute values that are used with WebView Identify function change, or if the political boundaries between some countries change (which is not very frequent).
In this paper, we have described in detail HCM cost-effective method for serving Web hypermaps with dynamic database links/drill-down functionality on the Web. The proposed solution is currently used for publishing HCM GIS-generated navigational information maps on the Web while maintaining their links with the underlying resource metadata base. The authors believe their map serving approach as adopted in HCM has been very successful, especially in cases when only map attribute data change without a corresponding effect on map appearance. However, the main benefits of HCM solution are that it is much cheaper and simpler to deploy and maintain (doesn't need full access to the hosting Web server to install and manage extra software components) compared to a full-fledged Internet mapping server solution. It should be also possible to use the same solution to publish other interactive GIS-driven maps on the Web, e.g., maps of real world health problems.
The authors would like to thank Dr. Christopher Austin president of GeoHealth, Inc., USA, who supplied BodyViewer v2.1 Extension Version (ICD-9) free of charge for the purpose of this research.
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