TerrainRouteOperator.RestrictedAreaSafety Property
Gets or sets an attribute variable giving the safety factor of each restricted area.
Syntax
public AttributeVariable< System.Double > RestrictedAreaSafety { get; set; }Property Value
Default: 0.0
The safety factor of each restricted area.
Remarks
By default, restricted areas have zero safety, which means they are completely forbidden to pass through. More generally, one can define softly restricted areas by assigning them a positive safety.
The RestrictedAreaSafety is an attribute variable that is normally evaluated using the attributes of each restricted area feature. More generally, the evaluation will also consider the View.UpdateAttributes, as well as the attributes of the feature from WaypointsInput.
The evaluated safety should be a number between 0.0, meaning no safety (a completely forbidden area), and 1.0, meaning full safety (the area will not be avoided). Intermediate values can be used to signify a dangerous area that should be used only reluctantly by the routing. When calculating a route, the operator will search for the route with the minimal penalized travel time: any travel time spent in a semi-safe restricted area will be penalized, since the assumed vehicle speed inside the area will be multiplied with the safety factor. For example, if the safety factor is 0.5, the usual vehicle speeds are halved inside the area, so that each true minute in the area will be counted as two during the optimization.
However, since the penalized travel time is not very interesting for the end user, the travel times reported as route leg attributes will be the true, unpenalized times.
If the safety is greater than zero so that the restricted area can be passed through, each output route leg will have six extra attributes for each value of the RestrictedAreaName, giving the travel time and distance spent in the named restricted area. For details, see the section "Softly restricted areas" in the operator class page.
In a specific tactical situation, it is impossible to predict in advance the most suitable values for the safety attributes. So the intention is that the TerrainRouteOperator can generate a list of alternative routes based on different safety values, and that human judgment is needed to choose one route, based on the route geometries and attributes.
For example, if the safety for each area comes from an attribute AREA_SAFETY, one could feed the operator with three waypoints features that are identical except for having AREA_SAFETY values of 0.0, 1.0, and 0.5. The operator would then generate three routes: one safe but perhaps slow route, one fast but perhaps dangerous route, and hopefully one compromise route. The three routes can be calculated within one update, and they can be distinguished since all route legs will have copies of the attributes of their waypoints feature (so the route having AREA_SAFETY = 0.0 would be the safest route).
Unfortunately, there can exist interesting compromise routes that the operator cannot generate regardless of the value of the safety factor. (This can happen because the time penalties are just a linear weighting that cannot find compromises that occur in a non-convex part of the so-called Pareto front; see for example Clawson et al., 2017.)
Platforms
Windows, Linux, Android