Software

Spatial Analysis with GIS

Spatial Modelling with GISSpatial analysis of GIS has developed greatly in recent years and continues to advance. The GIS software market provides this analytical functionality, though choosing the GIS software that provides the extent of spatial analytical functionality you require up to you – but any good GIS software wil provide a programming or scripting environment to allow you to add anything proprietary or new. Regardless, the scope of spatial analysis is extensive and includes data modelling, topological modelling, network modelling, cartographic modelling, geocoding, geostatistics, map overlays and more.

Spatial Analysis is powered by Queries

The ability to analyse your data is made possible via spatial and attribute data queries. The ability to use standard and to create your own queries of related spatial and attribute data is the key to effective analysis.

Again, good GIS software will provide you with standard queries for common analysis or at least advanced functionality to easily manipulate data without having to write or select queries. Furthermore, advanced analysis will require more detailed queries, so good GIS software should provide wizards and simple query builders to allow you to perform your own analyses.

The process of querying your data is simple – attribute data is initially queried and the relevant primary keys found These primary keys ar ethen used to query the spatial data, to complete the associate query required for both spatial and attribute data. For more example os spatial analysis please see, Wikipaedia andInformation Software Systems.

GIS Graphics: Rastor vs Vector

GIS GraphicsThe graphical representation of spatial and attribute data in GIS software takes the form of either raster or vector graphics. The differences between raster and vector graphics, as detailed below, effect the level of detail, visual appeal, speed of manipulating graphics and data storage space required.

Aerial photographs and satellite images are generally in a raster format and are used in GIS to view a detailed map at a given extent or for the purpose of digitizing. Raster graphics are predominantly used to display spatial data and use a grid-type architecture in terms of storing spatial and graphic value data. Vector graphics are commonly used to represent features like roads, rivers, housing, and the like using points, lines and polygons. Based on scalable vector graphics, vector graphics provide a linear and detailed approach to manipulating attribute data. Raster and Vector graphics are frequently used together.

Differences between Raster & Vector Graphics

The key difference between Raster and Vector graphics is how they are structured. Raster graphics use pixels (“dots”) whereby a graphic is made up of a large number of pixels, each pixel having a location & colour value in a grid-like format. A vector graphic is rendered by a mathematical manipulation referenced by co-ordinates. Given the different structure of these graphic types, the following differences arise as a result:

Raster Structure

Raster Structure

Vector Structure

Vector Structure

1. Storage Space: Raster graphics require more storage space than vector graphics, as they store a location & colour value per pixel.

pixels2. Detail: Raster images are more detailed within a given extent (“zoom”), however raster images become pixelated if too tight a zoom is applied. Vector images are less detailed, but maintain their original aesthetics regardless of extent or zoom.

3. Responsiveness: performance & responsiveness when manipulating vector image is faster than raster images, as the data structured used to render vectors is mathematically based whereas rasters requires the retrieval of individual pixel values and a manipulation of each pixel.

GIS Data: Spatial vs Attributes

GIS Data AttributesGIS Data is the key component of a GIS and has two general types: Spatial and Attribute data.

Spatial data are used to provide the visual representation of a geographic space and is stored as raster and vector types. Hence, this data is a combination of location data and a value data to render a map, for example.

Attribute data are descriptions, measurements, and/or classifications of geographic features in a map. Attribute data can be classified into 4 levels of measurement: nominal, ordinal, interval and ratio. The nominal level is the lowest level of measurement for distinguishing features quantitatively using type or class (e.g. tree species). Ordinal data are ranked into hierarchies but does not show any magnitude of difference (e.g. city hierarchy). The interval measurement indicates the distance between the ranks of measured elements, but a starting point is arbitrarily assigned (e.g. Celsius Temperature). Ratio measurements, the highest level of measurements, includes an absolute starting point. Data of this category include property value and distance.

Attribute data is the detailed data used in combination with spatial data to create a GIS. The more available and appropriate attribute data used with spatial data, the more complete a GIS is as a management reporting and analysis tool.

Sources of Spatial & Attribute Data

Spatial data can be obtained from satellite images or scanned maps and similar resources. This data can then be digitised into vector data or maintained as raster graphic data. Essentially, any format of a geographical image with location or co-ordinate points can be used as spatial data.

Attribute data can be obtained from a number of sources or data can be captured specifically for you application. Some popular sources of attribute data are from town planning and management departments, policing and fire departments, environmental groups, online media.

GIS Software on the Market

Vendors of GIS software supply a host of software and upgraded or carefully targetted version of GIS software. Please consult with the respective vendors to learn more about their respective products.

Some of the newer releases on the market are indicated here to help you find your way. Remember to look at our comparison of popular GIS software to help you to evaluate the best option for you.

New GIS Software Releases

1. IntelliGIS 2.0 – NEW!! – Relelase Date: Mid/Late 2008

US$ 1000.00 – best value for money for complete desktop GIS software

2. MapInfo 9.5 – New!! – Release Date: June 2008

US$ 3000 (approx.)- new professional edition with CAD functionality & .NET programming.

3. ArcGIS 9.3 – NEW!!! – Release Date: April/May 2008

ArcView US$1500 | ArcEditor US$7000 | ArcInfo US$14000

View our comparison of these popular GIS software solutions.

Build Your GIS: Choosing Software

GIS SoftwareGIS 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.

GIS Software

GIS SoftwareGeographic information can be accessed, transferred, transformed, overlaid, processed and displayed using numerous software applications. Commercial offerings of IntelliGISArcInfo 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.

View our comparison of some popular GIS software.

GIS Software Comparison

GIS SoftwareWhen 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
Key
Features
  • Mapping & Printing
  • Spatial & Attribute
    Data Analysis
  • Visual Data Editting &
    CAD
  • Extensive demographic data
    modelling
  • Enhanced Data Access
  • Programming Environment

 

  • Mapping & Printing
  • Spatial & Attribute
    Data Analysis
  • Visual Data editting
  • Extensive data modelling.
  • Extensive analytical
    capabilities.
  • Mapping & Printing
  • Spatial & Attribute
    Data Analysis
  • Visual Data editting
  • Report & Map Templates
  • Programming Environment
  • easy to use viewer/editor capable of displaying the
    most popular raster, elevation and vector datasets (now including
    GeoPDF®!
  • convert, edit, mosaic, reproject, print, track GPS
  • utilize GIS functionality on your datasets
  •  unsurpassed technical support with no extra
    support fees!
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.
Pro’s
  • Extensive demographic analysis
    & edittingtools.
  • Supports the latest database
    formats likeMS SQL 2008 Spatial .
  • Automatic feature options like
    labelling.
  • VB.NET & C#
    programming environment toadd MapInfo to other applications.
  • Map anti-aliasing coming soon.
  • Extensive product support.
  • Extensive analytical functionality
  • Extensive product support
  • Supports multi-user editting
  • Provides ready to use datasets like TIGER-2000 street
    maps.
  • Limited degree of appearance customizing using
    ArcReader wizards.
  • Supports 30+ data formats
    including Shapefiles,ArcSDE, MapInfo, OGIS, TIGER, Google KLM and more.
  • Store Data in any RDBMS using
    the full-wealthof database functionality available – like ArcSDE at no
    cost.
  • IntelliGIS Script Environment
    allows usersto develop extended functionality.
  • Create custom maps &
    reports.
  • Personal service & per
    request customisation.
  • Price
  • Supports hundreds of the best popular vector, raster
    and elevation data formats
  • 3D viewer
  • Capable of perfoming view shed analysis and watershed
    deliniation
  • Outstanding support
  • Price
Con’s
  • MapInfo data format
  • More attribute data focus than
    spatial
  • Price.
  • Locked into complex ESRI
    Object Model.
  • Frequent wholesale changes to
    Object Modelcreates version incompatabilities.
  • Locked into ESRI data format.
  • Price.
  • Relative smaller vendor than
    competitors likeESRI.
  • High-end analytical tools not
    included.
  • No SQL functionality
  • Small vendor
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: How it Works

GIS SoftwareGIS 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.

gis-layerThe 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

GIS Database SoftwareThe 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.

View our comparison of some popular GIS software.