Two step

The following parameters can be configured

• Two Step: Optimization will be executed in two steps. The First step will find an optimized solution. The Second step will trim and remove redundant swaths. Trimming will reduce the swath duration to cover only the strictly required area. Removal will delete those swaths not contributing, or with poor contribution, to the final coverage. The First step generates applicable swaths in sequence without forward search. The sequence is sorted according to Priority, Selection Criteria and Start Time. Therefore it is possible that a later swath will make previous swaths redundant. The Second step should remove those. Default: false.

Two Step OFF	Two Step ON

 

The Two Step algorithm is based on the concept of Incremental Contribution (IC):

- The Contribution of a swath to the coverage is the portion of the AOI covered by the swath (in the figure below is A +  B).

- The IC is the portion of the of AOI covered in exclusivity by the swath, without overlapping other swaths. It is provided as a % ratio. In the figure below IC = B / (A + B)

The two-step optimization algorithm will attempt to choose swaths with high IC, resulting in a final solution with low overlap.

The algorithm is iterative according to the following logic:

(1) obtain a first step optimization solution, and proceed to refine in the second step as follows

(2) remove all swaths with IC < "IC threshold"

(3) from the remaining swaths select the swath with lowest IC

(4) if "lowest IC" >=  "IC minimum" then go to step 9

(5) remove swath with lowest IC

(6) re-evaluate all the remaining swaths, by steering, resizing and panning to maximize their coverage of the AOI. As a result all ICs will be recalculated.

(7) evaluate the new resulting solution. If the AOI coverage obtained has an acceptable coverage loss ( < "Maximum coverage loss" ) then keep aside the solution as the currently preferred solution.

(8) loop back to step 2

(9) exit the algorithm proposing the preferred solution resulting of step 7

Configuring the two-step phase allows to define the following parameters

• IC threshold : swaths with IC below the incremental contribution threshold will be discarded. Default: 5 %

• IC minimum : once all the swaths have an IC above the incremental contribution minimum, the algorithm will exit the iteration. Default: 50 %

• Maximum coverage loss: Removing swaths progressively will result in a loss of coverage. Define the maximum coverage loss which is acceptable in the final solution. Default: 2%