Building a Standards Based Collaborative GIS

Building a Standards Based Collaborative GIS Ian Turton 1 and James Macgill 2 1 Centre for Computational Geography, University of Leeds, UK i.turton@geog.leeds.ac.uk 2 GeoVISTA Center, Department of Geography, Penn State, PA USA, jmacgill@psu.edu

Introduction

Collaboration

Open Standards

System design

Why Collaborate?

Collaboration is a vital part of many mapping projects

Maps often form the center piece of discussion and can be used to inform and improve a debate.

Teams from different agencies cooperating

Emergency response

Disaster relief management

Longer term project planning

Public participation

Types of Collaboration

Synchronous Same Place Collaboration

Every one uses same the map at the same time

Asynchronous Same Place Collaboration

Every one uses the same map but at different times

Synchronous Different Place Collaboration

Map is shared in space when everyone is present

Asynchronous Different Place Collaboration

Map is shared in space and time

Synchronous Same Place Collaboration

Simplest

All clustered around one monitor shouting “left a bit, right a bit...click there, no there!”

Can get boring very quickly!

More complex

Shared desktop/maps on multiple machines in one room

Most Complex

Shared display (e.g. Large wall display) participants can add data etc to main display allowing group interaction

Asynchronous Same Place Collaboration

This allows a group of users to share data and ideas using a map when some or all are present at different times.

Equivalent to being able to write on the map or leaving post-it notes on the map to pass on thoughts.

Synchronous Different Place Collaboration

All users present at same time but distributed spatially.

This allows users to have a shared map experience on their own desktop.

Individuals can show data and annotations to other users, data passed as features to allow local styling to be applied.

Internet

Asynchronous Different Place Collaboration

Users are in different places and are present at different times

Time zone differences

Collaboration over a long period

Need ability to annotate the map in a persistent manner.

Ability to save state in a useful manner, while allowing local styling.

Internet

Open Standards

Availability

Open Standards are available for all to read and implement.

Maximize End-User Choice

Open Standards create a fair, competitive market for implementations of the standard. They do not lock the customer in to a particular vendor or group.

Open Mapping Standards

WMS, WFS, WCS etc: These are discussed at length in the literature and will only be briefly described in this paper.

SLD: The ability to pass out a predefined style to all participants (GeoVISTA Studio) or to allow participants in different countries to view map in their preferred style (e.g. Geologists)

Annotation (XIMA): Allows participants to draw attention to interesting parts of the map.

Web Map Servers (WMS)

A WMS client passes an HTTP request to the server

Required layers and styling

Bounding box and CRS

Size and format of image required

A WMS passes a picture of a map to the client

Client can also request information about features at a point on the map

+ Security of data, simple client

- limited interactivity

Web Feature Servers (WFS)

A WFS client sends an HTTP request to a WFS

Features required (including filters)

Output format (often GML)

The server sends the result set

The client is responsible for styling and rendering the features returned.

+ faster rendering and queries, styling determined by client

- More complex client, potentially large data downloads, client holds data

Styled Layer Description (SLD)

An XML based language which describes how features are to be rendered.

Developed to allow WMS clients to choose from a selection of named styles when requesting a map.

Modern WMS allow the user to upload SLD or refer to a remote style repository.

This allows two users to view the same features but styled to local standards

Differential Styling

Xml IMage Annotation (XIMA)

Allows users to draw points, lines and polygons on to an image (WMS maps are images).

User can attach text, images, video, urls to the geometry.

The xima representation can be stored on a server and passed to other users.

A xima aware client can allow users to access the content of the annotations.

Annotated Map

System Requirements I

Synchronous Meetings

Publish maps to others in meeting

Highlight features of interest in own and other’s data.

Use data from local stores as well as remote sites

Communicate to other participants

Ability to save or publish outcome

System Requirements II

Asynchronous meetings

As before and

Persistence of maps and comments to allow participants to see previous discussion

Putting it together synchronously Remote Data Local Data Local Data Internet Publish maps and comments Publish maps and comments Receive maps and comments Receive maps and comments

Putting it together asynchronously Remote Data Local Data Local Data Internet Publish maps and comments Publish maps and comments Receive maps and comments Receive maps and comments Remote store

The client/server Map Client Map server User interface Communications GeoServer Mapserv Ionic Cubewerx GeoTools Deegree OpenMap Mapbender IMS VOIP Email Publish Receive

Transport Protocol