Defining a Spatial Analysis Component

The spatial calculation is defined as the altitude at various locations with respect to specified reference. The altitude is measured differently depending on the parameters listed below.

• Central Body. Selects central body for use as a reference for defining altitude.
• Shape Model. Selects reference ellipsoid, Terrain, or MSL (Earth only) as the reference shape for the selected central body used for defining altitude.
• Use custom reference. Enables an additional selection of the additional reference point.
• Reference point. Uses any point from VGT as a reference so that the altitude is defined relative to the altitude of this point.

The spatial calculation is defined as the angle to various locations with respect to the specified reference. The angle is measured differently depending on the parameters listed below.

• Off Vector. Uses any point and any vector from VGT, with the angle measured between the vector and the direction from the point to the location.
• Off Plane Signed/Unsigned. Uses any plane from VGT, with the angle measured between the plane and the direction from the origin of that plane to the location. Signed angle is positive on the plane side where its normal is directed.
• About Vector Signed/Unsigned. Uses any point from VGT to define a direction from that point to the location, and evaluates a dihedral angle formed between this direction and any vector from VGT measured about another vector from VGT. Signed angle is positive if measured right-handed with respect to that vector.

• Atmosphere Density Model. Selects one of several available density models.
• Enter Manually/Use File. Defines Flux and Kp/Ap parameters needed for certain density models either by manual entry or from a file.

The spatial calculation is defined as the distance of various locations from the specified reference. The distance is measured differently depending on the parameters listed below.

• From Point. Uses any point from VGT as a reference for measuring the distance of the location.

• From Plane Signed/Unsigned. Uses any plane from VGT as a reference for measuring the distance of the location. Signed distance is positive in the direction of plane surface normal.

• Along Vector Signed/Unsigned. Uses any vector and any point from VGT with the distance measured from the point to the location projected in the direction along the vector. Signed distance is positive in the direction of the along vector.

• From Point. Uses any point from VGT as a reference for measuring the distance of the location.
• From Plane Signed/Unsigned. Uses any plane from VGT as a reference for measuring the distance of the location. Signed distance is positive in the direction of the plane surface normal.
• Along Vector Signed/Unsigned. Uses any vector and any point from VGT with the distance measured from the point to the location projected in the direction along the vector. Signed distance is positive in the direction of the along vector.
• Speed Type/Value. Defines propagation speed across the distance measured according to the above parameters. The speed value can be either Custom, which is entered manually, or equal to the speed of light.

The spatial calculation is defined by placing its parent object at various locations on the grid and evaluating the selected (non-spatial) Scalar Calculation from the Calculation tool.

Volumetric evaluations using the Scalar At Location Spatial Calculation can become exceedingly slow in cases where the selected (non-spatial) Scalar Calculation is derived from times determined from Access or Chains computations; e.g., using Elapsed Time type of Scalar Calculation with reference Time Instant set to AccessStartTime.

A more efficient alternative is to:

1. Use a time component from Access or Chains computations to define a Spatial Condition using Valid Time At Location type.

2. From this newly defined spatial condition, create a Spatial Calculation using the Spatial Condition Satisfaction Metrics type.

This special type of calculation informs the volumetric object to first evaluate and store intervals of satisfaction for the underlying condition. Then the actual calculation can be evaluated quickly at any time via simple operations on these stored intervals.

• Spatial Condition. Uses any spatial condition from the Spatial Analysis tab of Analysis Workbench.
• Number of Intervals/Gaps. Defines the metric as the number of intervals of satisfaction or the gaps between them. The intervals can be filtered and their number accumulated in several different ways.
• Interval/Gap Duration. Defines the metric as the duration of the intervals of satisfaction or the gaps between them. The duration can be defined as Minimum, Maximum or Sun, and the intervals can be filtered and their number accumulated in several different ways.
• Time Since Last Satisfaction/Time Until Next Satisfaction. Define the metric as the time evolved since the end of the latest satisfaction interval or the time that remains until the next satisfaction interval (the metric is zero if inside the satisfaction interval). The time can be defined as Minimum, Maximum or Sum, and the intervals can be filtered and their number accumulated in several different ways.
• Accumulation Type. Defines how the metric evolves with time. It can be set as:
• Total - value accumulated over the entire analysis interval
• Current – instantaneous value
• Up To Current Time/From Current Time – value accumulated up to/from current time.
• Filter. Defines additional conditions that limit which satisfaction intervals are considered for the metric. It can be set to:
• None
• First/Last Intervals – limits the maximum number of intervals considered.
• Interval/Gap Duration - limits intervals to those of certain duration.

Moves the selected grid constraint object to specified locations on the grids and defines satisfaction as having Access between parent and the grid constraint object.

Constraints from both the parent and grid constraint object are used. Click Advanced Options... to configure Light Time Delay settings for Access evaluation.

The Grid Constraint object cannot be any ancestor or descendant of the parent object of the calculation.

• AND
• OR
• XOR
• Minus

The Minus operation is available when there are only two components in the combined list.

Moves its parent to selected locations on grids and then evaluates selected (non-spatial) condition from the Calculation tool.

Click Advanced Options... to configure computational settings for determining condition satisfaction.

Implicitly defines the bounding volume filled by the selected volume grid. Two types of extents are available:

• The first is based on coordinate edges that pass through the grid points on the outer edges of the grid.
• The second is based on voxel edges that pass through the outer edges of voxels centered on the grid points at the outer edges of the grid.

Both of these types are automatically available as embedded components for any installed or user-created volume grid.

Evaluates the satisfaction of any other spatial condition over specified intervals of time. It is considered satisfied within specified intervals if the original Spatial Condition is satisfied at any time within these intervals.

You can use any Interval or Interval List from the Time tool and additionally define the Duration Type as:

• Static
• Cumulative to Current
• Cumulative From Current
• Sliding Window (includes start and stop offsets from the current time)

Places numerical bounds on values produced by the Spatial Calculation. It is satisfied when the values are within specified bounds.

The bounds are defined by min and/or max values and the associated operation: Above Minimum, Below Maximum, Between Minimum and Maximum, Outside Minimum and Maximum.