Product(s):	LEGION
	Version(s):	CONNECT Edition
	Area:	Social Distancing

National social distance guidelines differ, but all use one of three standards: one metre, one-&-a-half metres, or two metres.  The table below shows how these social distances equate to radii and areas per entity, and invert to Cumulative High Density (CHD) map density thresholds (definable to two decimal places) in the far right column.

Social Distance (metres)	Radius/Entity (metres)	Area/Entity (square metres)	Entities/Area (people-per-square-metre to two decimal places)
1	0.5	0.785398163	1.27
1.5	0.75	1.767145868	0.57
2	1	3.141592654	0.32

To create a CHD map compliant with assessment of a two-metre social distance, based on an extended spectral progression applied across a 15-minute period:

1. In LEGION Simulator, open the Analysis menu and select Maps... from the list of alternatives.
   
   
   
   The Edit Map dialogue appears.
   
   
   
   
2. Click the All Types drop-down and select Map from the list of alternatives.
   
   
   
   The New button becomes available.
   
   
3. Click the New button.
   
   
   
   Map #001 is created with default parameters and the option to rename immediately.
   
   
4. Rename the map 'Social Distance CHD (2m)' and set its Parameters as follows:
   1. Metric: Entity Density
   2. Area: Whole Model, with Use Smoothing ticked
   3. Zone of Influence: Fixed radius of one metre (this should be half the target distance)
   4. Accumulation Method: Method: Count above the cut-off value; Cut-off value: 0.32 (from the table, above)
   5. Reset Interval: not applicable
      
      
      
      The Edit Map dialogue should look like that above.
      
      
5. There is no need to change the Entity Filter tab, as it filters for all entities by default.  So, go straight to the Value & Colour Ranges tab and select the Extended Spectral Progression value range from the drop-down list.
   
   
   
   
6. There are no Alternative Value Ranges, or Map Exclusions, so the map is ready to use and may be saved.  An example appears below.
   
   

Note that the map defined above uses the Extended Spectral Progression value range, which has an upper bound of 15 minutes, meaning that any area in which the 0.32 people-per-square-metre threshold is exceeded for longer than 15 minutes will remain magenta.  However, custom value ranges may be user-defined, where different timescales are needed.

Note also that Entity Density is constrained by proximity to obstacles, as well as other entities, so will rise in constrained space, even if there are no other entities nearby.

Lastly, social distance implementations differ, with some measuring stopping points two metres apart (excluding people's dimensions) and others including space for people, based on average or maximum dimensions.  Those accounting for people's dimensions in their assessments should use the data in the table below to increase their target distances and map thresholds accordingly.

Widths      (metres)	Female		Male
	Mean	Max	Mean	Max
Asia	0.295	0.392	0.298	0.387
China	0.295	0.392	0.298	0.387
North America	0.321	0.396	0.349	0.43
Southern Europe	0.321	0.396	0.347	0.427
United Kingdom	0.321	0.396	0.349	0.43

LEGION system entity size profiles were derived from publicly available anthropomorphic data.  Circle diameters are the distances between the outer edges of people's shoulders, also called bi-deltoid widths.