Spatial Network Analysis Software

Spatial network analysis software packages are computer tools used to prepare various graph-based analysis of spatial networks. They stem from the research field of space syntax in the domain of architecture, although they can now be used to analyse road networks over an entire continent.

As the domain of space syntax has expanded, there are now a plethora of tools associated with it. Since most were developed within the academic community, most tend to be free for academic use, and some are open source.

In historical order:

• Axman The (near) original developed by Nick Sheep Dalton of UCL to perform axial line analysis on computers running Mac OS, currently used in more than 50 countries. This spawned many offshoots such as Pesh (for the analysis of convex space networks) and SpaceBox (for the analysis of 'all-line' axial maps).

• Spatialist Developed at Georgia Institute of Technology to implement theoretical innovations principally introduced by John Peponis, this software is plugs into the MicroStation CAD package to analyse networks of automatically generated 'e-spaces' and 's-spaces'.

• Axwoman 1.0, written by Bin Jiang while at UCL, is a tool to perform axial analysis as a plug-in to ESRI products.

• Axwoman 6.0, evolved from Axwoman 1.0 and many years of research by Bin Jiang and his team. Axwoman 6.0 is a free plug-in to ArcMap 10, combined with AxialGen in one single installer. Featured functionality include automatically generating natural streets and axial lines from OpenStreetMap data. The website also contains a set of tutorials for self-learning.

• Depthmap Developed by Alasdair Turner of UCL, this software was first developed to generate isovists and perform visibility graph analysis of building systems on computers running Windows, but now includes the automatic generation of axial line networks and analysis of axial line networks and road segment line networks at anything up to the level of the USA or Europe.

• OmniVista Developed by Nick Sheep Dalton and Ruth Conroy Dalton to perform a range of isovist measures on Mac OS computers.

• Fathom, a commercial implementation of visibility graph analysis written by the Intelligent Space Partnership.

• Mindwalk Developed by Lucas Figueiredo, This software performs spatial analysis over standard axial maps and new continuity maps. It is written in Java and runs on several platforms. Also known as xSpace, Mindwalk has been used as a research and teaching tool at several institutions since 2002 and now it is being distributed worldwide for academic and non-commercial purposes.

• Isovist Analyst by Sanjay Rana while at UCL, this program creates isovists from building plans as a plug-in to ESRI products.

• Ajanachara. Open source software developed by Gerald Franz at the Max Planck Institute for Biological Cybernetics to perform visibility graph analysis of 3D Studio Max and VRML models.

• Webmap Also developed by Nick Sheep Dalton at UCL, this software is free to use (although it requires registration), and allows users to analyse axial maps through a web browser interface.

• Confeego Developed by the commercial company Space Syntax Limited, but available free for academic use, this software plugs directly into MapInfo to analyse line axial networks.

• AJAX by Mike Batty of UCL, performs both traditional axial network analysis (Batty calls this the primal analysis), and point-based visibility analysis introduced by Bin Jiang (which Batty calls the dual analysis). In a recent paper, Batty shows the elegant mathematical relationship between the two analyses.

• OverView plug-in to AutoCad by Christian Derix for Aedas Architects in collaboration with the Center for Evolutionary Computing in Architecture CECA. Allows architects to do quick visual integration mapping via isovist analysis on their projects. Contains also the possibility to analyse non-planar environments to take volumes and hilly sites into account.

• AXess 1.0 by Jennifer Brisbane at the City University of New York. A context menu tool for ArcGIS 9.x that calculates connectivity, control, mean depth, global integration, and local integration for all nodes in an axial line layer. Free download available at ESRI ArcScripts.

• Webmap-At-Home by Nick Sheep Dalton UCL. A Java implementation of the original Axman program with a number of extra features added. This is a platform neutral full application capable of reading DXF files and the original Axman binary format. Free download available at WebmapAthome .

• AxialGen by Bin Jiang and Xintao Liu at the University of Gävle, Sweden. It is a plugin to ArcGIS 9.2 that generates automatically the axial lines for a complex polygon with holes.

• Layout-iQ 1.0 Developed by Nelson Lee at Rapid Modeling. Used extensively in healthcare, manufacturing, banking, retail, and office space, Layout-iQ is a software that evaluates the frequency of flow in a workspace and measures the total travel distance that resources will travel to navigate through the workspace. The software integrates CAD drawings with a diagram of flow between points. The thickness and color of the flow lines indicate the intensity of flow in each line, so users can visually see high priority point to point relationships. As the user moves locations in the diagram, the software dynamically calculates the impact on travel distance and users can immediately see the impact of the change on operations. The software also allows for the creation of improved aisles and paths using the aisle effectiveness measurement and actual path diagramming.

• Urban Network Analysis Toolbox for ArcGIS (free, open-source) Developed by the City Form Lab at SUTD and MIT. The UNA Toolbox can be used to compute five types of graph centrality measures on spatial networks: Reach; Gravity; Betweenness; Closeness; and Straightness. The tools incorporate three important features that make them particularly suited for spatial analysis on urban street networks. First, they can account for both geometry and topology in the input networks, using either metric distance (e.g. Meters) or topological distance (e.g. Turns) as impedance factors in the analysis. Second, unlike previous software tools that operate with two network elements (nodes and edges), the UNA tools include a third network element – buildings – which are used as the spatial units of analysis for all measures. Two neighboring buildings on the same street segments can therefore obtain different accessibility results. And third, the UNA tools optionally allow buildings to be weighted according to their particular characteristics – more voluminous, more populated, or otherwise more important buildings can be specified to have a proportionately stronger effect on the analysis outcomes, yielding more accurate and reliable results to any of the specified measures. The toolbox is built for easy scaling – it is equally suited for small-scale, detailed network analysis of dense urban areas as it is for sparser large-scale regional networks. The toolbox requires ArcGIS 10 software with an ArcGIS Network Analyst Extension.

• SSA Plugin by Burak Beyhan at the Mersin University, Turkey. Space Syntax Analysis (SSA) Plugin is operational on a series of Free and Open Source Software for GIS (FOSS4GIS) including OpenJUMP, gvSIG, OrbisGIS, Quantum GIS, OpenEV, Thuban, MapWindow GIS, SAGA, and also R Project. SSA Plugin calculates the standard space syntax measures including connectivity, total depth, mean depth, global integration, local depth, local integration and control values for each feature involved in a spatial configuration, and intelligibility value for the whole of the configuration. In addition to these parameters, users are also allowed to export adjusted graph created by the plugin to an external file in a Social Network Analysis (SNA) file format for further analysis of the spatial configuration concerned in the respective software environment.

• Spatial Design Network Analysis (sDNA) (free) a tool aiming to unify the use of spatial network analysis in the disparate fields of design and research. To this end, plugins are provided for Autocad (for designers), ArcGIS (for analysts) and a standalone Python version that works on shapefiles enabling use in other GIS software and custom projects. sDNA standardizes on the network link as a unit of analysis, and computes a wide variety of closeness, betweenness, severance and efficiency measures. Analyses can use Euclidean, angular or custom distance metrics, and link, length or custom weightings.