What is GIS
Geographical Information Systems Explained
GIS Software: How it Works
GIS Software works by combining a visual front-end, a database driven backend, incorporated with extensions that allow references between spatial and attribute data to support spatial analysis. But what doe sthat mean?
Considering the key component of spatial and attribute data first, the database portion of GIS software provides a store for spatial data to allow map rendering. In addition, further database or database table can be incorporated to provide attribute data, growing the scope of related data and allowing for more complex and original spatial analyses. Hence, the database back-end is a collection of spatial and attribute data using RDBMS like SQL Server or MySQL.
The visual front-end is like a reader that displays spatial and attribute data in layers or themes. Each theme represents a specific dataset, which can be toggled to customised what data is visual at any time. The front-end provides the user interface to perform data queries, directly manipulate the maps, perform spatial analysis and produce reports.
The GIS extension can be any collection of GIS specific tools or a GIS engine that provides the front- and back-end capability and GIS functionality. These extensions allow the wide scope of view, selection, editting and many more tools to manipulate your GIS data.
GIS Data & Software Structure
The structure of a GIS incorporating multiple data sources and GIS software would look be as follows:
The diagram could be an example of a GIS used to analyse the environmental impact of transport in an area relative to private economic activity. This is indicated by the sources of data for transport, environment, demographics, employment along with the spatial data.
The visual display of this data is via GIS software, the provides a layered approach to viewing data.
Most GIS take on this structure and it is mostly a question of what extent of data is appropriate for use.
GIS Software Comparison
When choosing your GIS software, being either a GIS specialist or organisation needing a complete GIS software package, it can be daunting deciphering the functional differences between offerings. For example, what is the difference between ArcView and ArcEditor, and why do the cost so much? Why is MapInfoclassed as more suitable for demographic data? And how can IntelliGIS cost a fraction of the price of ArcEditor yet offer so much functionality? To save you the headache, the software comparison below is a starting point for comparing ArcView, MapInfo, ArcEditor, IntelliGIS and Global Mapper.
MapInfo, ArcEditor, IntelliGIS & Global Mapper Compared
| Criteria | MapInfo | ArcEditor | IntelliGIS | Global Mapper |
| Vendor | Pitney Bowes | ESRI | ISS | Blue Marble Geographics |
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| Usability | Regarded as one of the most usable GIS offerings providing XP/Vista style interface. |
Windows 2000 style interfaces look dated, though tools are still intuitive to use. |
Windows XP & Vista Style interface provides familiarity with intuitive visual tools & wizards. |
Very easy to use although the “hidden” features can be rather cumbersome to find. |
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| Price | US$ 1994 approx. per license. Not pricing is readily available so approach reseller for quote. |
US$7000 per licensing plus maintenance costs. This excludes any ArcInfo functionality which is an additional US$14,000. |
US$ 1000 per license (optional extensions & customisations cost extra) |
$399 per license |
| Verdict | Very attractive & user-friendly offering & widely used for more demographic GIS needs. Its moderate price is preferred to ESRI products. For attribute data focused GIS. |
Most extensive, spatially focused GIS, but very costly & restrictive in terms of object model & data formats. Only for very serious spatial GIS Specialists with budget. |
Best value for money given scope of functionality, openGIS, RDBMS use and data formats supported. Choose IntelliGIS! |
Best Value for the money given scope of functionaltiy and supported formats! |
| Download Trial | N/A | N/A | N/A | Download Trial |
GIS Software
Geographic information can be accessed, transferred, transformed, overlaid, processed and displayed using numerous software applications. Commercial offerings of IntelliGIS, ArcInfo and MapInfo provide an entire suite of tools, with these offerings generally being market leaders. Custom software and open source products (i.e. GRASS) are also common but require in-house skill to use and maintaine effectively. A number of online IMS (Internet Map Services) are also available for public use, such as Google Earth.
Types of GIS Software
GIS Software is a diverse as other categories of software and ranges from the simple to complex, general to niche offerings targetted at the broad range of possible GIS uses.
1. Managment & Analysis GIS software is the most commonly referred to GIS software. This GIS software type commonly combines both an extensive database back end & a visual front end. This software combines a broad scope of functionality to support those trained in cartography and geography, as well as GIS professionals. This software supports the greatest and most prominant scope of GIS functionality and is the cornerstone of professional analysis and GIS data representation. Examples include IntelliGIS and ArcGISproducts.
2. GeoDatabases are a database with extensions for storing, indexing, querying, and manipulating geographic information and spatial data.The primary function of geodatabases are the “database type” capabilities that it gives to spatial data. Some of these capabilities include easy access using standard database drivers such as ODBC, the ability to easily link or join data tables, also indexing and grouping of spatial datasets independent of software platform. Examples of a geodatabase includes a current RDBMS like Oracle, SQL Server, MySQL installed with spatial extensions like Oracle Spatial, ArcGIS or PostGIS.
3. Readers are a more streamlined GIS software option that allows viewing of geographic data and maps, but provide little to no map and spatial data editting. This software is often cheaper or free, and useful for embedding in other applications.
4. Free & Open-Source GIS software provides much the same scope of functionality as described above, but in a free or open-source format. Hence, the use of open-standards for development & in-house support are required, the costs of which need to be offset against the free acquisition of such software. Examples include GRASS GIS, Quantum GIS, MapServer, uDig, OpenJUMP, gvSIG and many others.
Build Your GIS: Choosing Software
GIS software provides the functionality to create, manipulate, analyze and display maps and geographic data [learn more].
GIS software can be relatively simple or extremely complex and should be selected based on its appropriateness to your needs and cost-benefit analysis. Keep in mind your immediate as well as future GIS needs when making your GIS software decision.
Simple Mapping Options
Simple mapping options provide functionality to view and print maps. Simple mapping options take the form ofviewers or readers, which provide little to no GIS functionality. If your needs are simple, these software options are effective as they are either free or very cheap (<US$400), provide the needed map presentation and interface with internet mapping services like Google Earth and Microsoft Virtual Earth for further enhancement.
This software option provides very limited spatial analysis capability & usually doesn’t meet the needs of GIS people or organisation, but rather the needs of simple users.
Desktop GIS Options
Desktop GIS options provide the necessary spatial capabilities for GIS software, but to an extent depending on the type of data you intend or expect to handle.
Simple GIS Software: If you are limiting the data you intend to use to demographic data represented via a map presentation, then simple GIS software like Microsoft MapPoint or ESRI BusinessMap is appropriate. These options are affordable (<US$700) and provide extensive attribute data analysis capability referenced simply to spatial data. Subsquently, natural resource or geographic management is not best served by this options.
Basic GIS Software: this is appropriate if you require a fully featured GIS software that allows access to a wide range of data, perform relatively robust analyses and produce highly effective maps. An example is ESRI’s ArcView. This option is effective as GIS software provide your needs for spatial data editting is limited and your need focus more on spatial and attribute data analysis. The cost of this software ranges from $1,000-2,000, with annual maintenance fees of $2-300 per installation.
Advanced GIS Software: Expert-user software that can perform just about any function you might need. This software includes an extensive array of options and modules. The most well-known brand is the ESRI ArcInfo, though few make use of this type of software given cost ($10,000-20,000 per license) with hefty annual maintenance fees ($2-3,000 per user per year). Similar options but more cost effective offerings are available, namely Information Software System’s IntelliGIS. IntelliGIS provides very similar extent of functionality of say ArcInfo and ArcEditor, but at a more reasonable cost (approx. US$1000). This GIS software option provides the bulk of GIS functionality you’ll require & is intended to provide the professional land management & GIS solution.
Build Your GIS: Data Capture
Obtaining data to insert into a GIS is a large subject in itself that includes a number of different approaches. One of the most common ways to collect spatial geographic data is to perform a physical survey to obtain primary/proprietary data. This includes surveying the land, underwater areas, and underground features of the earth (which are referred to as field survey, hydrographic survey and mining survey respectively).
Aerial photography/remote sensing is an increasingly popular way to gather spatial data. Aerial photographs are taken from an aircraft, after which they are measured and interpreted. Similarly, satellite remote sensing can be interpreted for physical features and attributes.
Censuses conducted by the U.S. Census Bureau gathers a variety of demographic data such as population, age structure, sex ratio, race composition, employment rates.
Statistics are a set of mathematical methods used to collect and analyze data. These methods include the collection and study of data at different time intervals and at a fixed location, providing information for yearbooks, weather station reports, etc. This information often has a spatial component and can thus be incorporated into a GIS.
Finally, tracking is a process of collecting attribute data on changes that occur at a location over a period of time. Examples of tracking include: monitoring the change of an ecosystem, and real-time monitoring of a moving objects such as vehicles using GPS technologies.
Public & Commercial Sources of GIS Data
- US Geological Survey (USGS) – Free Air Photographs
- Centre for Advantage Spatial Technology (CAST) – US State and Natural Resources Data
- GIS Data Depot – free GIS data and more
- Collins Software – Free Data by Region
Be sure to search for new data sources online as the GIS community continues to grow. Also ask your muncipality for local spatial and attribute data.
Build Your GIS Solution
Building your GIS solution requires deciding on and acquiring the necessary hardware, software and data to support your need. The success of any system implementation , which is particularly true of GIS, is planning!
A key planning consideration is establishing the Startegic Purpose of the GIS solution for your organization. Such purpose guides the scope of functionality & output required of your GIS solution.
Like all solution developments, requirements & specifications for your GIS needs should be established. In doing so, the data required and how it will be used to produce the necessary information output is determined. Effectively, you are designing the scope of the system in terms of data input, processing capabilities and output.
The system scope define the tools – hardware and software – needed to make the solution a reality. When deciding on hardware, the nature of data capture (in-field or centralized), the accuracy tolerance and real-time vs delayed processing must be established. Remember, your hardware requirements for your GIS solutions should partner your existing IT infrastructure as far as possible.
GIS Software is probably your must critical decision with regards implementing your solution. You need to match you system scope to the functionality of the GIS software options, consider cost-effectiveness of the investment and importantly the compatibility and scalability of that software selected. An investment into a product that exceeds your functional needs and locks you into a specific data type or model can be very expensive at the outset and in the long-term respectively.
Implementation through acquisition, data capture and training should then follow to make your GIS solution a success.