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Web GIS
Web GIS is the implementation of geographic information systems (GIS) functionality through a World Wide Web browser or other client program, thus allowing a broader usage and analysis of a particular geographic database. Also referred to as Internet GIS, distributed GIS, and Internet mapping, the implementation of online GIS systems has dominated the work of GIS professionals since the late 1990s.
Examples of Web GIS have proliferated. Online map-based property information systems developed by local governments are early and important examples that demonstrate the clear benefit of this technology. Such systems can be used to compare tax assessments between properties and are viewed as vital tools in promoting fairness in taxation and a democratic society. Web GIS is a central element in public participation GIS (PPGIS) or participatory GIS (PGIS). The notion here is to bring the tools of GIS to the public so that stakeholders in a particular decision can reach a common consensus rather than relying on decision making by a single entity. Participatory GIS stands in contrast to project-based and enterprise-based GIS, which are characterized by a limited number of users and/or the maintenance of a large but private database.
Client-Server Model
Web GIS is based on the client-server model. Figure 1 depicts the typical client-server architecture, the most common distributed computing model. In this system, clients request services that are provided by servers. The server may be viewed as a dominant computer that is connected to several client computers having fewer resources, though the client may vary a great deal in terms of hardware and software characteristics and may actually have a faster processor. The distributed model provides an open and flexible environment in which a wide variety of client applications can be distributed and used by large numbers of computer users.
The major Web server program is Apache. Begun in 1995 as a series of “patches” (thus, the name “Apache”) to an HTTP (HyperText Transfer Protocol) server running at the National Center for Supercomputer Applications (NCSA) at the University of Illinois, Apache is now an open source Web server software maintained by the Apache Software Foundation. It is available for many different platforms, including Windows, Unix/Linux, and Mac OS X. At least 70% of all Web server implementations use Apache.
While many Web GIS implementations require a Web browser only on the client end (“thin clients”), some implementations require additional software or plug-ins. These “thick clients” (also referred to as “fat clients”) use additional client-based software to facilitate more advanced operations and functions on the data and services accessed through the Web. Some predict that all software in the future, including that for GIS and word processing, will be served via the Web and use a thick-client model.
Commercial Implementations
Although initially slow to adapt to the World Wide Web, commercial GIS companies have introduced a variety of online implementations of their software. An early commercial online GIS application is ESRI's ArcIMS (Internet Map Server). ArcIMS uses a typical client-server-based approach. The server responds to user-based requests and returns a map to a Web browser in a raster-based format like JPEG. Other implementations, such as Intergraph's GeoMedia, use a thick client to support client-server interactions.
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- Analytical Methods
- Analytical Cartography
- Cartographic Modeling
- Cost Surface
- Cost-Benefit Analysis
- Data Mining, Spatial
- Density
- Diffusion
- Ecological Fallacy
- Effects, First- and Second-Order
- Error Propagation
- Exploratory Spatial Data Analysis (ESDA)
- Fragmentation
- Geocoding
- Geodemographics
- Geographical Analysis Machine (GAM)
- Geographically Weighted Regression (GWR)
- Georeferencing, Automated
- Geostatistics
- Geovisualization
- Image Processing
- Interpolation
- Intervisibility
- Kernel
- Location-Allocation Modeling
- Minimum Bounding Rectangle
- Modifiable Areal Unit Problem (MAUP)
- Multicriteria Evaluation
- Multidimensional Scaling (MDS)
- Multivalued Logic
- Network Analysis
- Optimization
- Outliers
- Pattern Analysis
- Polygon Operations
- Qualitative Analysis
- Regionalized Variables
- Slope Measures
- Spatial Analysis
- Spatial Autocorrelation
- Spatial Econometrics
- Spatial Filtering
- Spatial Interaction
- Spatial Statistics
- Spatial Weights
- Spatialization
- Spline
- Structured Query Language (SQL)
- Terrain Analysis
- Cartography and Visualization
- Analytical Cartography
- Cartograms
- Cartography
- Choropleth Map
- Classification, Data
- Datum
- Generalization, Cartographic
- Geovisualization
- Isoline
- Legend
- Multiscale Representations
- Multivariate Mapping
- National Map Accuracy Standards (NMAS)
- Normalization
- Projection
- Scale
- Shaded Relief
- Symbolization
- Three-Dimensional Visualization
- Tissot's Indicatrix
- Topographic Map
- Virtual Environments
- Visual Variables
- Conceptual Foundations
- Accuracy
- Aggregation
- Cognitive Science
- Direction
- Discrete versus Continuous Phenomena
- Distance
- Elevation
- Extent
- First Law of Geography
- Fractals
- Geographic Information Science (GISci)
- Geographic Information Systems (GIS)
- Geometric Primitives
- Isotropy
- Layer
- Logical Expressions
- Mathematical Model
- Mental Map
- Metaphor, Spatial and Map
- Nonstationarity
- Ontology
- Precision
- Representation
- Sampling
- Scale
- Scales of Measurement
- Semantic Interoperability
- Semantic Network
- Spatial Autocorrelation
- Spatial Cognition
- Spatial Heterogeneity
- Spatial Reasoning
- Spatial Relations, Qualitatitve
- Topology
- Uncertainty and Error
- Data Manipulation
- Data Modeling
- z-Values
- Computer-Aided Drafting (CAD)
- Data Modeling
- Data Structures
- Database Management System (DBMS)
- Database, Spatial
- Digital Elevation Model (DEM)
- Discrete versus Continuous Phenomena
- Elevation
- Extensible Markup Language (XML)
- Geometric Primitives
- Index, Spatial
- Integrity Constraints
- Layer
- Linear Referencing
- Network Data Structures
- Object Orientation (OO)
- Open Standards
- Raster
- Scalable Vector Graphics (SVG)
- Spatiotemporal Data Models
- Structured Query Language (SQL)
- Tessellation
- Three-Dimensional GIS
- Topology
- Triangulated Irregular Networks (TIN)
- Virtual Reality Modeling Language (VRML)
- Design Aspects
- Geocomputation
- Geospatial Data
- Accuracy
- Address Standard, U.S.
- Attributes
- BLOB
- Cadastre
- Census
- Census, U.S.
- Computer-Aided Drafting (CAD)
- Coordinate Systems
- Data Integration
- Datum
- Digital Chart of the World (DCW)
- Digital Elevation Model (DEM)
- Framework Data
- Gazetteers
- Geodesy
- Geodetic Control Framework
- Geography Markup Language (GML)
- Geoparsing
- Georeference
- Global Positioning System (GPS)
- Interoperability
- LiDAR
- Linear Referencing
- Metadata, Geospatial
- Metes and Bounds
- Minimum Mapping Unit (MMU)
- National Map Accuracy Standards (NMAS)
- Natural Area Coding System (NACS)
- Photogrammetry
- Postcodes
- Precision
- Projection
- Remote Sensing
- Scale
- Semantic Network
- Spatial Data Server
- Standards
- State Plane Coordinate System
- TIGER
- Topographic Map
- Universal Transverse Mercator (UTM)
- Organizational and Institutional Aspects
- Address Standard, U.S.
- Association of Geographic Information Laboratories for Europe (AGILE)
- Canada Geographic Information System (CGIS)
- Census, U.S.
- Chorley Report
- Coordination of Information on the Environment (CORINE)
- COSIT Conference Series
- Data Access Policies
- Data Warehouse
- Digital Chart of the World (DCW)
- Digital Earth
- Digital Library
- Distributed GIS
- Enterprise GIS
- Environmental Systems Research Institute, Inc. (ESRI)
- ERDAS
- Experimental Cartography Unit (ECU)
- Federal Geographic Data Committee (FGDC)
- Framework Data
- Geomatics
- Geospatial Intelligence
- GIS/LIS Consortium and Conference Series
- Google Earth
- GRASS
- Harvard Laboratory for Computer Graphics and Spatial Analysis
- IDRISI
- Intergraph
- Interoperability
- Land Information Systems
- Life Cycle
- Location-Based Services (LBS)
- Manifold GIS
- MapInfo
- Metadata, Geospatial
- MicroStation
- National Center for Geographic Information and Analysis (NCGIA)
- National Geodetic Survey (NGS)
- National Mapping Agencies
- Open Geospatial Consortium (OGC)
- Open Source Geospatial Foundation (OSGF)
- Open Standards
- Ordnance Survey (OS)
- Quantitative Revolution
- Software, GIS
- Spatial Data Infrastructure
- Spatial Decision Support Systems
- Standards
- U.S. Geological Survey (USGS)
- University Consortium for Geographic Information Science (UCGIS)
- Web GIS
- Web Service
- Societal Issues
- Access to Geographic Information
- Copyright and Intellectual Property Rights
- Critical GIS
- Cybergeography
- Data Access Policies
- Digital Library
- Economics of Geographic Information
- Ethics in the Profession
- Geographic Information Law
- Historical Studies, GIS for
- Liability Associated With Geographic Information
- Licenses, Data and Software
- Location-Based Services (LBS)
- Privacy
- Public Participation GIS (PPGIS)
- Qualitative Analysis
- Quantitative Revolution
- Spatial Literacy
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