sDNA Software

“[...] the first essential step in the direction of learning any subject is to find principles of numerical reckoning and practicable methods for measuring some quality connected with it. I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely in your thoughts advanced to the state of Science, whatever the matter may be.”

“If you can not measure it, you can not improve it.”

William Thomson, 1st Baron Kelvin, writing in 1883

 

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sDNA Software allows you to measure your spatial networks

Currently, we support both Autocad 2010+ and ArcGIS 10+: the former has a workflow more suited to designers, while the latter includes more advanced capabilities for researchers and analysts.  Additionally sDNA can be run standalone on shapefiles prepared in any other program, and developers can take advantage of our Python API for any purpose – including experiments in parametric design.

  • Industry standard data compatibility Use off-the-shelf Ordnance Survey data and a variety of other spatial formats with a minimum of preparation.
  • Universal network analysis standard sDNA uses the network link (the fundamental “atom” from which all networks are constructed) as the base unit of analysis, giving repeatable results not achievable with other spatial units (such as axial lines and address points) and avoiding the modifiable link unit problem.
  • Complex foundations, quick and simple to use Use angular analysis as a proxy for human perception of route cost.  (Metric and custom analyses available too).
  • Continuous space and geometry Treat network links as continuous, rather than discrete entities to ensure accuracy.
  • Multi-scale Customize the locality of analysis, measure accessibility on a range of different scales, or flows for a range of different trip lengths.
  • Customizable Use custom link weighting and costing if you want – though having said that, we get perfectly good results without the hassle of custom analysis!
  • Superb accuracy.  Our calculation engine is one of our greatest strengths, tested against datasets from the literature it achieves equal or better results in all cases.  Every build is also regression tested against our suite of hand-computed networks.
  • Supreme speed.  We support multi-core CPUs, and are working on other ways to make spatial network analysis even faster.

 

Measures computed

All measures can be based on metric, angular or custom costs, with uniform or custom weighting per link or per unit length.

  • Accessibility within radius
    • Closeness (compatible with existing literature)
    • Improved accessibility measures
    • Network gravity model
  • Flows/Betweenness for radius
  • Network density within radius
    • Link count
    • Junction count
    • Total connectivity
    • Total length
    • Total angular cost
    • Total weight
  • Severance
    • Total/mean geodesic length
    • Total crow flight distance
    • Mean geodesic diversion ratio
  • Efficiency
    • Convex hull area
    • Convex hull perimeter
    • Convex hull maximum radius
    • Bearing of maximum radius
    • Hull shape index
  • Two phase (generation/assignment) model
    • Two phase betweenness
    • Two phase destination weight

 

Requirements

  • OS: Microsoft Windows XP or Windows 7
  • Host application: one of
    • Any application that can read/write the open shapefile format (we recommend the free QGIS), or
    • Autocad 2010, 2011, 2012 or 2013 (older versions since 2000 will probably work as well – if you have one, try it and let us know!), or
    • Autocad Map 3d, or
    • ArcGIS 10.0 or later
      • Service pack 1 or later recommended (it’s free, and they fixed some crashes)
      • Network Analyst extension is NOT required (this saves you a couple of grand!)
    • We think sDNA will run on AutoCAD Architecture, AutoCAD Civil 3D, AutoCAD Electrical, AutoCAD Mechanical, AutoCAD MEP, AutoCAD P and ID, AutoCAD Plant 3D, AutoCAD Raster Design, AutoCAD Structural Detailing – though we haven’t tried them.  If you fancy giving it a go, please do, and let us know how it goes!
  • Suggested minimum hardware:
    • 1 Gigabyte of RAM, more preferred for large networks.
    • Any modern CPU can run sDNA, but if you want to analyze large networks, the faster the better!
Any questions, please get in touch.
 
Photo credit:
Kelvin statue, Belfast (detail) (Albert Bridge) / CC BY-SA 2.0