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 [5].
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).
WebView features
WebView
was developed by Thomas Zerweck at ZEBRIS in Munich, Germany (http://www.zebris.com/
– [6]). It was
programmed in Avenue (an ArcView scripting language), HTML (HyperText
Markup Language – for the Web templates) and JavaScript (to add
additional interactive functionality to its client-side Web maps).
It is much cheaper compared to a dedicated ESRI Internet Map
Server solution, though not as powerful as the latter.
A
WebView wizard leads users through the necessary steps in ArcView
GIS and creates the project's Web pages (based on the active view
in ArcView at the time the wizard is launched – Figures 4,
5
and 6).
These pages can then be edited manually if necessary in any HTML
editor. The created map pages and interface can provide the
following functionality [6]:
-
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.
Version
2.1 of WebView provides additional features (not available in
WebView v1.1). These include five zoom levels, transparent layers
(users can switch layers visible/invisible) and object layers
(Figure 7).
The latter provides a client-side map feature lookup functionality
"similar" to, though not as powerful or sophisticated as
that provided by dedicated map servers. Developers select up to
two themes as object layers. An object layer is a theme, in which
the user may search for certain attribute value. The attribute
values are listed in a combo box, e.g., a list of country names as
in the screenshot above. Selecting a country from the list, will
cause the detail map (on the left) to zoom to that country and
mark its exact position on the map (Figure 7)
[6].
WebView
limitations
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
In
HCM, the authors developed their own (partial) workarounds for
these limitations of WebView (Figure 8).
This solution makes use of WebView HotLink functionality to
implement a dynamic database drill-down that will always reflect
the latest updates to this database. By clicking different
hotspots on the client-side imagemaps in HCM, users are actually
triggering server-side pre-formulated SQL (Structured Query
Language) queries against an underlying database of resource
metadata. The database is registered on HCM server (a Windows
2000/NT 5 IIS Server – Microsoft Internet Information
Server/Services) as an ODBC (Open DataBase Connectivity) Data
Source (Figure 9)
and is the same database we are connecting to in ArcView. We coded
the SQL queries in ASP (Active Server Pages) pages for execution
on the server. The ASP pages returned to users in their browsers
only contain query results in the form of formatted HTML. The
actual SQL and ASP code as found in the ASP pages stored on the
server is never sent to the end user.
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.
The
resource metadata base was implemented in Microsoft®
Access (Figure 10).
We used ArcView "SQL Connect" feature to connect to HCM
metadata base and import all fields and records from it into an
ArcView table that will refresh each time the project is opened in
ArcView (Figures 11
and 12).
This is the same database currently registered on HCM server as an
ODBC Data Source (Figure 9
above), which users query by clicking the hypermaps.
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 [7].
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).
We
used BodyViewer "Setup Wizard" to map the Internet
resources listed in HCM onto the human body (Figures 13
and 14).
These resources have been indexed in the metadata base that we
imported into ArcView in the previous step (see Figure 12
above). The mapping is based on the three ICD-9 fields in the
imported table. BodyViewer can aggregate more than one ICD-9 code
field at a time, and so was able to use all three DC subject
fields in HCM metadata table combined to compute resource counts
by clinical subject category/body region. BodyViewer classifies
resource counts per body region into ranges and associates each
range with a colour shade or tint, i.e., a choropleth rendition
(darker colours meaning more resources). This allows us to
visually spot infogaps (topical coverage gaps) and infoclusters.
(Infogaps can be also due to insufficient indexing by HCM.)
In
ArcView, BodyViewer views are not hot-linked to the underlying
resource metadata table (within ArcView) until we perform
what is called "Link Patients" in BodyViewer, though in
this case we will be linking resources not patients. Although
BodyViewer was able to aggregate three ICD fields in the previous
step, the linking can only be done using one DC subject
field at a time (Figure 15).
The result of the linking in ArcView is shown in Figure 16.
In this regard, the corresponding HCM human body maps on the
Web are superior since the linking query (running on HCM Web
server) looks in all three DC subject fields in the
underlying metadata base. To export BodyViewer maps (views) to the
Web using WebView, we have to first select a Map Unit
("meters") for the view or else WebView will not be able
to determine a scale for rendering the detail map and will abort
the process (Figure 17).
We inserted a HotLink field in BodyViewer map tables to store the
Web addresses of corresponding ASP query pages that will run on
HCM Web server; this field is associated with the HotLink mouse
event feature of WebView (Figure 18).
HCM World map in
ArcView
The
authors used the basic World map dataset that ships with ArcView
GIS 3.1 as a project example (world.apr), and added a HotLink
field to the "Countries ('98)" table (Figures 19
and 20).
This field was associated with the HotLink mouse event in WebView
wizard when the authors generated HCM World Map for the Web.
Clicking a country on HCM World Map (on the Web) will launch the
appropriate country query to retrieve only those resources
authored in and/or published in the clicked country. Query results
will always reflect the latest updates carried on the
metadata base without the need to change any code.
It
is also possible to join the resource metadata and World
Countries tables (within ArcView) based on the values of a common
field (country names – Figure 21).
This kind of functionality is not possible with WebView.
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