On October 29th, 1999, members of the Apoala research group introduced a prototype model of a same time-different place collaborative environment at the WebGIS conference held in State College, PA.

Exploratory analysis of complex, multi-dimensional space-time data sets demands new and innovative tools. As an extension from the Apoala Project, individuals in the GeoVISTA Center and the Center for Academic Computing are working together to explore the potential of same-time-different place collaboration among scientists at remote locations as they explore complex spatiotemporal data.

Many potential scientific, educational, and decision-making applications for Geographic Visualization (geovisualization) involve small groups working together on a problem solution, but existing tools are designed for use by individuals. We developed a prototype geovisualization environment focused on same time-different place collaboration. Such environments have potential application to regional and local planning/decision-making, scientific research by distributed interdisciplinary teams, and web-based education.

Screen Capture of the Collaborative Environment

Our prototype, consisting of a series of linked desktops, is designed to facilitate collaboration among users who are exploring time series of climatic data for a large drainage basin. The exploration involves interaction with shared dynamic (animated and interactive) displays. The prototype is constructed from a set of Java/Java3D tools. These include VisAD, a DEM viewing module that works with VisAD, and our own extensions for data queries and networking. In relation to query, we focused on temporal query tools designed to help users explore both linear and cyclic components of the ata.

The prototype collaborative geovisualization environment allows multiple users to view and manipulate the changing climatic data simultaneously and thus to share knowledge as they identify drainage basin scale patterns and processes. Though the Java language operates across platforms and operating systems, dealing with different levels of hardware performance and Internet access speeds represent future challenges for implementing ideas explored here. The data used in the demonstration are extracted from a much larger climate data set for the Susquehanna River Basin of Pennsylvania, New York, and Maryland -- specifically daily maximum temperature, minimum temperature and precipitation extending from 1983-1993.

Types of Collaborative GIS/geovisualization

  • same place - same time
    • planning meeting; Group SDSS
  • same place - different time group
    • activism; PPGIS
  • different place - same time
    • teleconference
  • different place - different time
    • world campus GIS courses

Our prototype is a system of linked desktops using Java/Java3D (VisAD + DEMViewer + our extensions). VisAD and the DEM Viewer are explained below.

VisAD – Java (2D/3D) class library for interactive and collaborative visualization and analysis of numerical data… primary author: Bill Hibbard, Space Science and Engineering Center University of Wisconsin, Madison


DEMViewer is a digital elevation model viewer for ArcGrid ASCII export files. It is written in Java and uses VisAD and Java3D

DEMViewer was developed by Ugo Taddei, Department of Geoinformatics, Geohydrology and Modelling, Institute of Geography, University of Jena, Germany.


In order to create a collaborative environment, it was necessary to build a TalkServer allowing communication among different computers.

TalkServer is a JAVA application for communicating user initiated events among networked collaborative applications. TalkServer was developed at the Visualization Group of Penn State's Center for Academic Computing. Hadi Abdo is the primary author of TalkServer. TalkServer listens on a predetermined port of a server for new connections from client applications. For each new socket connection detected, TalkServer creates a TalkServerThread (TST) to communicate with the connected client application.  When a TST receives subsequent messages from its client application that indicate changes that will effect other clients in the collaborative session, the messages are relayed to the TalkServer. TalkServer then requests that all TSTs update their corresponding clients accordingly.




Animated View Window

The animated view window allows collaborating users to manipulate the 3-D cube in all directions. The program also allows the users to zoom in and out from all angles. The example above displays precipitation distribution across the Susquehanna River Basin, with green indicating precipitation.

Cyclic Legend

The cyclic legend was developed to allow users to query the data for cyclical phenomena. In the above example, the user has chosen to animate only the summer months (June, July, August, and September) between 1983 and 1992.



The Animation Control box allows the user to start the animation, or step through with each click of the mouse. The text box allows the user to specify the speed of the animation. (333 ms/frame is equivalent to three frames per second and 1000 ms/frame represents 1 frame/second). We are currently investigating ways to make the animation speed selector more user friendly.

The linked desktops are sychronized when the GO button is pressed. The computers will stay relatively close to the same speed, however, delays can occur due to network speed as well as differences in the relative CPU speed required for animation of the data displayed on each client's monitor.

Vertical exageration is controled by the bar on a scale of 1-10. In the future, we hope to allow the user to specify the boundaries of this scale. The color selector allows the user to select all possible color combinations by manipulating the red, green, and blue curves in the spectrum. The numbers contained on the legend represent the range of values taken from the data loaded into the program (in this case the maximum temperature range is from 51 degrees F to 99 degrees F.

The Animation by Day selector shows the user which file is being displayed in the viewable portion. The user can move the slider to select individual days. There are 31 separate tick marks on this slider bar representing the 31 days of the month.


  • Link the environment to an object-oriented database that supports more flexible queries
  • Make the time selector a dynamic legend
  • Develop more flexible and complete interaction -- e.g., color selection
  • Add temporal averaging tools experiment with more than two collaborators
  • Compare same & different place collaboration
  • Transfer the prototype into IDesk environment

The visualized data comprise the full extent of the Susquehanna River Basin (SRB), which covers over fifty percent of the land area of Pennsylvania, part of west-central New York, and a portion of Maryland on the Chesapeake Bay. The extent ranges from about 39.5° N to 43° N latitude and 75.5° W to 79° W longitude. The physiographic regions of the SRB stretch from the Piedmont in the southeast corner to the Appalachian Plateau in the upper half of the basin. Nestled between these two physiographic regions and accounting for the majority of the lower half of the basin's areal extent is the Ridge and Valley province.

The raw data, provided by the National Climatic Data Center in Asheville, North Carolina, span a period from 1948 to 1993. Between 250 and 300 data recording stations collected the raw daily maximum temperature, minimum temperature, and precipitation measurements, with an average of 150-200 stations actually contained within the boundaries of the Susquehanna River Basin on any given day. First, unreliable data were eliminated, and the temperature data were corrected for localized topographic variation by standardizing the values to Mean Sea Level. The data were then interpolated into a 4km cell based grid. Finally, a Digital Elevation Model was used to restore the elevation values to the temperature data sets.