"In the future, GIS users could work on GIS data by using their web browsers without installing a GIS software on their local machines" Penguin, Z-R and Tsou M-H (2003)
"(InternetGIS systems) come very close to delivering the functionality expected by a professional working with GIS, and, providing that response times are sufficiently fast and high-quality printouts are available (through downloadable PDF or post-script files for example, they can replace a desktop GIS for many purposes" Jones, C. B. and Purves, R. S. (2008)
Professional and academic opinions have differed over the years on the place of Geoweb 2.0 standards operators and the improvements made with Geoweb 3.0. This have dragged going to a decade now and then one begins to wonder why the differences despite the acceptance of the deliverables across the globe.
What we have today on Geoweb is data resources seamlessly in plug-and-play mode with other online spatial data sources; online spatial data processing services interoperating distributed databases, chaining together with other processing services to form loosely coupled applications allowing users to query online catalogues to discover the data services and processing the services they need.
Geoweb technically means bending the facilities offered by the web to suit the needs of geospatial data processing, incorporating web-mapping and web based Geo-services.
The emergence of no-cost services such as Google Maps, Yahoo maps, Microsoft's Bing Maps, Virtual Earth, Open Layers etc. has added populist element to the Geoweb. Anyone with the fairly minimal knowledge of computing- Activistss, hobbyists, whoever- can access the Web's rich sources of spatial data and create their own online mapping.
We are in post Geoweb 2.0 era that implements interactive/democratic web/human to machine communications incorporating Wikis, Blogs, Mashups, Volonteered information and AJAX Applications. Google Maps, Yahoo maps, Microsoft's Bing Maps, Virtual Earth, Open Layers and Neogeography are providing Geoweb 2.0 Services. Over a hundred other mapping services are listed today.
Geoweb 3.0 technologies are already being implemented without having a convincing edge while visionaries are already discussing what Geoweb 4.0 will look like.
It's estimated that the release of Google Maps/Earth has increased GIS users (broadly defined) from 1 million to 100 million, Sui 2008.
It is however important that we understand that GIS is a system that solves problems based on the ability to query a built mirror image of life's events. Which means you first model the reality of the events and activities and extract intelligent information and knowledge.
The problem solving ability of GIS means it is a tool and not a science. However, there are several scientific disciplines like physics/electronics, material science, statistics, mathematics, computer science/ programming and geodesy (projection) that provide knowledge to build an efficient systems. Their inputs have brought GIS to where we are today. That helps us to understand were Cache, Apps etc are coming from, making near realtime map generation possible by online mapping services providers the edge over the 1.5 Geoweb applications and taking maps into the door step of interested users. Google and other online mapping services have not done anything beyond serving maps and providing apps for customizing individually motivated deliverables by providing apps and other gadgets.
How Google revolutionized mapping service.
When it was released on 7th February 2005, Google Maps immediately made other online mapping services look desperately old fashioned. Previous mapping systems, based on Geoweb 1.5 approaches required that an entire web page be re-generated each time the user make alterations to an online map. We were used to clicking and waiting. Google now offers what has come to be known as " sloppy map interface. By moving the mouse, users can slide the map around the map window, and unless the map is moved very rapidly, the map seems to be seamless.
Google maps, like other online mapping services, operates within conventional browsers, requiring no plg-ins, no flash etc. it is ultimately a thin client solution. It is therefore important to explore how current mapping services are managed.
The answer is that rather like AJAX itself,current online mapping services are essentially clever and efficient integrations of existing technologies rather than based on single radically new technology breakthrough. For example, Google maps technology foundation includes:
a. AJAX
Google maps is the archetypal Ajax application and it's 'Slippy map' interface has revolutionized the expectations of online mapping services. Ajax as a technology allows Google maps to function like a desktop application, although in detail, Google maps uses an alternative to XMLhttpRequest to facilitate asynchronous communication with the server. The embedded HMTL page can be refreshed without needing to reload the main page.
b. Map Tiling
Although the Google maps appear to be seamless: it is in fact a mosaic of pre-rendered map tiles. Every tile within the Google maps system, whether map, satellite or hybrid view is pre-prepared. Each tile has dimensions of 256 by 256 pixels and about 12 Kbps in size, which make them individually very quick to download. Each visible Google 'map' is a grid of five or more rows and columns of presently unseen tiles around the edges of the visible area that are loaded in anticipation of the user panning the map. If you move you mouse in a diagonal direction across the screen, tou may be able to see the tiles loading.
c. Map Compression
Google maps data supplier 'Telcontar' stores the map files in a highly compacted proprietary Rich Map Format RMF that aids fast transfer. Yahoo also use the same supplier but the data are rendered differently to look dissimilar.
d. Map Tile Caching
Caching algorithms ensure that data that are most frequently used are positioned so that the can be most quickly retrieved. In Google maps, the most frequently used tiles are the fastest to be recalled. As most users will tend most times to look at particular parts of the world- their city, the locality of their home etc. the map tiles of those areas are likely to already have been stored in the web caches of the users' PC from previous sessions, so Google maps can provide this tiles for subsequent sessions without ever leaving the users' machine. Google takes advantage of the caching mechanism that is built into the web system for its own purposes. Google technologies have improved over the years but having served on a GIS project which Google also participated, I have come to the conclusion that Google do not offer complete GIS services and can best be said to do online mapping service.
What Google spawned was nothing but a great awakening. The advent of Google maps is not the "GIS Killer" or " Killer App", it was a promoter. It was the platform that allowed more people to see the utility of geospatial information. Francica (2008)
GIS is not all about data and information, it is also concerned with the validation of the quality of results produced by the system. It also entrench itself among others in large scale institutional data arrangement, sharing and usage which the present online mapping services providers are presently incapable of doing. For example, they can not afford to invest and operate large scale resource applications across the globe because of the peculiarity of each localities. Large scale land/cadastral, utilities, buildings, city information etc. sensitive to states and local government administration are presently beyond them. Collecting data for location and street searches, low accuracy terrain classification, ability to lay individual data on service providers maps are issues of democratization of data and not core GIS issues.
Serious earth data for earthquake, Sunamis, tremors are not detected or monitored using data from phones or 5 meter accuracy GPS, but with geodetic equipments. They all bother more on data presentation and the usability depends on the target application and use.
I know that opinion differs and diverse opinions converge to bring out facts and embrace logical sentiments. My opinion is that there is an on going convergence of the earth resource fields forcefully pushed by emerging technologies, especially the world-wide-web making all of us to cross what used to be natural boundaries like it is also happening in arts and humanities. However, technology should not just direct our paths out of excitements, it should help in exposing the reasons for the high increase in the frequencies of occurrence of earth problems, earthquakes and all.
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