3.2.6 Measure isovist values in a field analysis

The ‘Field Analysis’ menu allows the user to assess the metric values of isovists at all locations in a space, and plot these in a colour representation, or a ‘field’. A total of ten ‘local’ isovist fields and eleven ‘global’ space syntax fields can be calculated by the Isovist_App. To generate and measure these fields:

  • Import the drawing to be analysed, check that the drawing scale is set to an appropriate value, and check that the correct regions for analysis have been selected.
  • Set any required links between different spatial regions by using the ‘drawing and setup menu’.
  • Switch on the required isovist spatial types for analysis (i.e. Accessible, Visible, Reflected or Spectral) in the isovist analysis menu. By default, field analysis is conducted just using ‘accessible’ isovist space.
  • Set any preferred isovist parameters (i.e. sweep, direction, or rims) in the isovist analysis menu.
  • Open the ‘Field Analysis menu’ and chose either the Basic or Advanced modes from the foot of the menu. The advanced mode gives access to extra field options, but slows the running of the calculations, so may not always be suitable.
  • Use either the ‘Isovist measures’ or the ‘Space Syntax measures’ drop down menus to select the fields to be reviewed. The requested field should subsequently become visible as a coloured fill on the drawing.
  • Wait… The analysis runs in real time and rapidly develops from a stochastic sampling process to give a statistically stable field of values. The time required to complete varies relative to complexity of field measure  chosen and computer device power. 
  • Review the local and global cycles counts, visible in the primary menu at the top left of the Isovist_App window, to help assess when a field analysis is ‘complete’. Local isovist measures tend to be statistically stable after 3-5 local cycles, and global space syntax measures after 200+ global cycles.
  • To display numeric values at locations in the field, select the ‘toggle overlays’ option from the isovist analysis menu, and choose ’overlay absolute values’. Move the cursor to any location in the field and the numeric value for that field at that location should appear beside the cursor. Remember that the numeric values are dependent on the drawing unit scale previously set.
  • To fine tune the visualisation of each field result, use the ‘upper limit’ and ‘lower limit’ sliders in the field analysis menu. Numerous alternative field colour schema can also be chosen from the tab immediately below these two sliders.
  • To switch between viewing the measure results as a 2d field or 3d landscape, select from these two options below the colour schema options tab.
  • To completely reinitialise the field analysis, press the ‘reset’ button at the foot of the field analysis menu. The existing field results will be wiped and a new analysis started.

Below: Reviewing measure fields within Hans Hollein’s Monchengladbach Museum

Scans can either be viewed in a 2d ‘field’ form; or as a 3d ‘landscape’, with peaks and troughs through the plan space reflecting result magnitudes.

Below: Switching between 2D and 3D representations of scan results within Mies’ Barcelona Pavilion