GEOGRAPHICAL INFORMATION SYSTEMS
Leveraging intelligent data from aerial surveys.
LEVERAGING SPATIAL DATA
Our clients need to be able to extract useful information from our maps and we are able to help put spatial data to work. Geographical Information Systems (GIS) is the tool of choice and we can advise and assist in the purchase and implementation of systems from the single farmer to enterprise level. As our company is not tied to any one GIS package we feel that our strength lies in our independence and can openly direct clients in the most appropriate direction.
Our company is also able to continue assisting clients right through to implementation. A combination of local knowledge and programming skills mean that we are able to customise most applications and can write specialised applications that can convert and integrate spatial data from almost any source either as a one off or on a continuous basis.
OPEN SOURCE GIS
A growing initiative of the firm is the development of web based client/server GIS applications geared towards removing the burden of spatial data leveraging from our clients. These applications are based on Open Source technologies which offer a more cost effective and arguably better solution than that of traditional GIS vendors.
The older GIS practice of gathering, analysing data and publishing results still have their place but these days the wider GIS definition and concepts can be exploited. Using new technologies, data can now be gathered directly from the field and piped straight into a central spatial database for processing. Results can be made available immediately and can be published directly from the databases onto the web. This type of work flow can greatly enhance data collection, eliminate systematic errors and reduce data acquisition to dissemination times while still falling within the framework of a GIS.
Projects of this nature comprise of a wide range of data collection, storage and management requirements which make it impossible for any one piece of software to satisfy. Servicing these needs efficiently requires a “stack” of software running from either central servers or “cloud servers” receiving field data and disseminating out to the screens of users with web browsers.
ENTERPRISE LEVEL SYSTEM ARCHITECHTURE
The concept of a “geostack” is very similar to any other enterprise software stack and comprises of three tiers: a base tier that is devoted to data storage and integrity, a middle tier for data processing, and a top tier for data presentation.
A typical “geostack” consists of the following functional parts:
- Spatial database that can provide random access to large data sets, query processing that understands spatial relationships, and transactional integrity during concurrent editing. Examples include Oracle Spatial, SQL Server Spatial, PostGIS/PostgreSQL.
- Desktop software that can provide direct editing and visualisation of data in the database. For data management, quality control, and ad hoc reporting. Examples include ArcGIS, MapInfo, QGIS, uDig.
- Cartographic map renderer reads spatial data from the database, applies styling rules and outputs map images. Examples include ArcIMS, ArcGIS Server, MapServer, MapGuide, GeoServer.
- Application server that can provide a programming framework for custom applications. Examples include ArcGIS Server, GeoServer, MapGuide.
- Map tile server that can store pre-rendered image tiles and serve them up quickly to make maps refresh faster. Examples include ArcGIS Server, MapGuide, Tilecache, GeoWebCache.
- Web map component that can provide a map component inside a web browser. Examples include Google Maps, OpenLayers.
It should be noted that some products occur in the above list multiple times and this is because some software provide multiple functions. There are advantages and disadvantages to such products but generally a more modular design is preferable. Such a system allows singular components to be deployed separately, and upgraded on different cycles and reduces exposure to the traps in single vendor systems.
THE OPEN SOURCE GEOSTACK
There are significant benefits to the deployment of open source technologies in enterprise level applications which are leading to it’s large scale adoption by governments and corporate entities world wide.
Some examples are:
- Initial Costs are dramatically reduced. Open source software is freely available and there are no license restrictions with its use. This initial cost benefit should not, however, be confused with long term maintenance costs which are typically higher.
- Community Support is widely available through a world wide network of developers and users. This eliminates the dependence on a single vendor who could disappear overnight.
- Open standards are adhered to and hence there are no propitiatory formats and access to ones data is always guaranteed.
- Customisable Software is in the nature of Open Source software as one is able to alter the source code to accommodate changes as required.
A further substantial benefit to open source solutions is their modular nature. Modularity makes it possible to combine the best parts of a variety of software and vendors. It is entirely feasible to combine proprietary software products with open source tools where preferable. For example, an Oracle database can be integrated with an ESRI desktop system and an Open Source web mapping application such as MapServer.
AN OPEN GEOSTACK EXAMPLE
- Postgresql and PostGiscombine an object-relational database with a spatial framework and support for geographic objects. Comparable proprietary products would be ESRI SDE and Oracle spatial extension. PostGis used the Simple Features for SQL specification from the Open Geospatial Consortium (OGC) and hence all data is stored in entirely open source formats.
- QGis is the Open Source answer to Arcview 3. It has a very similar look and feel and is an entirely useable desktop GIS system.
- GeoServer is server side software which reacts to requests from a web browser through OpenLayers and generates geographical web objects dynamically. The software is written in Java and is the reference implementation of the OGC Web Feature Service (WFS) and Web Coverage Service (WCS) standards. GeoWebCache is a simple caching engine that is used to speed up repetitive requests in a multiuser environment where server time can become imperative. Implementations of GeoWebCache can dramatically reduce hardware requirements and/or improve reaction time. GeoWebCache also conforms to the Web Map Server (WMS) standard.
- OpenLayers is an open source toolkit that is loaded into the web browser for creating queries to the GeoServer through GeoWebCache. If the required tile does not exist in the cache GeoServer will create it.