VisibilityOperator.MaxDistance Property
Gets or sets the maximal range of the observer, in meters.
Syntax
public AttributeVariable< System.Double > MaxDistance { get; set; }Property Value
Default: 15000.0
The maximal range in meters.
Remarks
Beyond MaxDistance the observer sees nothing (or is not a threat). See also DistanceVariation.
The four derived operators may disagree on whether the MaxDistance should be interpreted as a horizontal distance or in three dimensions.
The VisibilityIndexOperator always interprets the MaxDistance as a horizontal distance.
The LineOfSightOperator, the TargetLineOfSightOperator and the AirspaceCoverageOperator can use either interpretation, possibly depending on an observer attribute, via the property maxDistanceType. The three operator types does not all have the same default value for this property.
In TargetLineOfSightOperator, the MaxDistance has no hard limit. But if the LineOfSightOperator or the VisibilityIndexOperator get integer elevation rasters, then the MaxDistance is limited by the VerticalUnit and the Refraction; the following table give some examples of the longest allowed maxDistance.
refraction | meter | foot | decimeter |
|---|---|---|---|
1.00 (none) | 847 000 m | 373 000 m | 204 000 m |
1.15 (light) | 909 000 m | 399 000 m | 219 000 m |
1.33 (radar) | 977 000 m | 430 000 m | 235 000 m |
If you use a longer MaxDistance than allowed, no exception will be raised:
The estimated visibility indices from a VisibilityIndexOperator will be only slightly less accurate, except perhaps if the sensorHeight is extremely high.
In the output from a LineOfSightOperator, at the longest allowed MaxDistance from the observer, there should appear a thin circle that is erroneously marked as visible.
And remember that if the input elevations come as float rasters, then these limitations do not apply.
Platforms
Windows, Linux, Android