In the last week or so I have noticed a number of posts on Twitter, LinkedIn and the like talking about the number of choices available in Open Source GIS. This list is exhaustive and you can check out The GIS Forum for the most exhaustive list available. So this list is huge, so what? Well this means that there are now enough choices that you can develop and maintain an enterprise level GIS without the costly licensing that is associated with proprietary implementations. As an example a comparison of an enterprise GIS deployment might look like this:
ArcIMS - $18000
UMN Mapserver $0.00
ArcSDE - $18000
PostGIS/PostgreSQL - $0.00
ArcMap - $2500
Quantum GIS - $0.00
Total Proprietary - $38,500
Open Source - $0.00
Of course this doesn't even factor in the yearly licensing cost of the proprietary software. Sounds like a no brainer...right? Well maybe not. Companies such as ESRI have spent years and millions of dollars to ensure their software is completly compatable accross the board. What I mean by this is, if you deploy a completely ESRI solution it is very likely that each part will interact with each other part very well. Because the open source projects are run, for the most part, fairly independantly this may not be the case for OSGeo. However, more and more OSGeo packages are croping up that put these software together in interoperable bundles. Some examples are the OSGeo4W project which is a grouping of such GIS powerhouses as Quantum GIS, FWTools/OpenEV and uDig. Another example is the GISVM which is a Ubuntu Linux VMWare image that can be run on Windows, Linux or Mac OS using the VMWare viewer and contains a number of GIS applications such as gvSig, Grass GIS and PostGIS.
The power of any GIS lies in it's customizability. For proprietery platforms they have development environments such as VBA and libraries that contain a number of progamable objects such as ArcObjects. Open source is no different. As an example Quantum GIS has a number of bindings for languages such as Python and C++. These bindings allow the developer to create embeded plugins to extend the functionality of the software as well as stand alone applications that can provide a highly focused set of features to the user.
So what does all this mean. Well it is true that there are many open source choices to help build a highly functional and powerful GIS for your organization, it is still imperative that you perform a comprehensive needs analysis. This can be done completely in-house or with the help of a consultant but is essential. This will help you know exactly what the system needs to produce and allow the developers and deployers to pick the right applications to meet your busines objectives.