We have developed a robust TimeMap viewer application (TMWin) which will display
both local and internet-accessible datasets together in a time-enabled
map window. The viewer uses time-based filtering to display time slices
on demand and will generate simple map animations as AVI files. We have
also developed a powerful Java map viewer for Internet-accessible
datasets. The Java map viewer may be embedded in any web page and supports on-the-fly temporal queries. Both TimeMap viewers are key enabling
technologies for the Electronic
Cultural Atlas Initiative.
Windows Map Viewer: TMWin
TMWin is a Windows application written using Borland Delphi and the ESRI
MapObjects GIS component. In addition to normal mapping functionality,
such as zooming, panning, labelling and symbolisation of map layers,
the TMView has specialised temporal mapping functionality.
Time-enabled GIS: TMWin creates map layers on the
fly by applying an SQL filter to vector datasets (stored locally
as ESRI shapefiles), allowing the map to be updated as the
time limits are changed. A time bar beneath the map - which
can be zoomed in to individual days, months or years, or out
to the full time range of the datasets displayed - allows
the user to set the time limits by dragging the ends of the
current time range shown by the grey bar.
on methods of handling time.
The TMWin Interface
Map Animation: The TimeMap methodology allows for
explicit recording of 'snapshots' as vector GIS objects, and
of 'transitions' as attribute data attached to them. TMWin
uses this principle to generate map animations, which can
be output as .avi (movie) files, to illustrate the passing
Access Internet Datasets/ Distributed GIS: TMView
can search and access remote datasets through a metadata
clearinghouse developed for the Electronic
Cultural Atlas Initiative (ECAI) and can integrate both
local and remote datasets together in a time-enabled map window.
Inset showing dragable timebar
- Map-object to resource linking: One of the essential
functions of TMWin is the linking of objects on a time-filtered
map to local or web-based resources – such as web pages,
photographs, multimedia or other maps. Map-object to resource
linking is the key to spatial and temporal browsing of large
datasets, such as heritage inventories, and a key component
of our strategy in developing museum-based visitor access to
historical data. TMWin was used to build a museum kiosk -
Sydney TimeMap - at the Museum of Sydney in November 2000. It has
also been employed in public information kiosks for the Parramatta
Historical and Archaeological Landscape Management Study.
Clearinghouse Browser: TMWin includes a map-based
metadata clearinghouse browser which allows:
- connection to remote datasets
- filtering of the clearinghouse based on spatial and temporal
limits and metadata searches
- display of bounding boxes for datasets on a map of the
- display of metadata for selected datasets, including
extended HTML-based documentation
- display of thumbnail and detail views of datasets.
Remote datasets are filtered on the server, the subset is
downloaded and cached locally, allowing for offline access
and the responsiveness of a local application rather than
Internet data transfers.
Visual cues to layer display range
MapSpace Manager: TMWin has a MapSpace Manager window
which supports the design and saving of multi-layer maps as
MapSpace files (analogous to ArcView projects or MapInfo Workspaces).
MapSpaces define the datasets to be used (including non-local
datasets accessible via the ECAI metadata clearinghouse),
the SQL filters to be applied to create map layers, the symbology
to be applied for each layer, and spatial and temporal limits.
Layer configuration dialogue
- Layer control: TMWin handles both time and layer display
scaling. In TMWin, layers can be set to display both within
particular scale ranges and within particular date ranges using
simple visual metaphors. Visual metaphors are also used in the
legend of the map window to indicate which layers lie outside
of the current display range. A clock symbol indicates that
the layer lies outside the current time range for the map, a
plus magnifying glass indicates one must zoom in to see the
layer, and a minus magnifying glass that one must zoom out.
When a greyed-out layer is highlighted in the legend, its spatial
extent is flashed on the map and its temporal extent is flashed
on the time bar.
Java map viewer
While much of our work has gone into development of the Windows map viewer
and data preparation toolkit, it became clear that the download and installation
of a complex Windows application was a significant hurdle for the average
user simply wishing to retrieve data in a web browser. This led us to develop
a Java mapping applet which may be embedded in any web page.
The TimeMap Java map viewer is an intelligent client which downloads vector
and raster data and can handle temporal filtering, data-driven hotlinks and
access to distributed heterogeneous datasets indexed in a central metadata clearinghouse.
In addition, because the TimeMap Java viewer downloads data rather than
dumb images, it can handle immediate zooming and panning, time filtering,
switching layers on/off and popup information on map rollovers. This contrasts
with the approach of downloading an image generated on a server and returning
to the server for each pan, zoom or enquiry. The intelligent client approach
makes for a much more responsive application once the initial download has
|Embedding the Java map viewer in your web pages
providing an immediate interactive mapping capability without installation
of any complex or expensive software on your web server. Embedded maps can
draw on the increasing number of free-access datasets registered in the ECAI
Metadata Clearinghouse. These include worldwide background maps as well as
more local datasets. The applet may either be pasted into a web page - in
which case it will display a set of datasets specified by their ID numbers
in the ECAI metadata clearinghouse - or it can
be called to display the results of an online clearinghouse search such as
that illustrated below.
Organisations can add
datasets to the clearinghouse, and to their embedded maps, through an
open web interface. Suitable shapefiles, GIF or JPG files already on your
web site can be added to the clearinghouse in a matter of a few minutes and
become immediately mappable. SQL server databases with locational information
(e.g. latitude and longitude columns) can also be easily added to embedded
maps. Access to the data can be password controlled.
Hot links on the map can be built through a simple metadata
specification which allow the applet to link from objects on the map to different
pages in a complex web site (for example to pages generated from a database
e.g. for a heritage sites register or photographic catalogue).
Individual solutions for organisations which wish to maintain their
own data for interactive mapping, rather than drawing on the ECAI Metadata
Clearinghouse, can be built rapidly thanks to a drop-in XML metadata
clearinghouse file and CGI scripts which can be easily installed on
most servers. The only support technology required is standard, off-the-shelf
tools downloadable free from the Internet. For further information,
the TimeMap development
team. The Showcase-Applications page features several customised examples of the Java Viewer
The applet currently supports data ranging from simple zipped shapefiles,
GIF and JPG images on a web server to data servers such as the MrSID image
server, a number of SQL data servers (MySQL, Interbase and Sybase for example). General Open
GIS Consortium Web Map Server and Web Feature Server compatibility should
be available soon.
|Parameter settings on the applet allow specification of the following:
For the applet as a whole:
- Source of applet and data
- Size of applet window
- Initial and maximum spatial extent (latitude/longitude)
- Initial and maximum temporal extent
- Background colours
- Components of the interface to show/hide
- Tool buttons to show/hide
- Automatic layer ordering on/off
- Layer title
- Initial visibility
- Temporal display range
- Spatial display range
- Incremental loading on zoom, pan and time change
- Rendering (size, colour, symbols)
- Access passwords
The applet is approximately 500K in size with necessary libraries and will
run within the standard VM in Internet Explorer 4 and above on PC, Unix and
Mac. For Netscape 4 and above, Java VM 1.3 is required (free download from
Sun for PC & Unix, not available for Mac).