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What Figures of Merit to use for Remote Sensing missions?

Posted 7 months ago by Land Sea Air Space

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Land Sea Air Space

Hi everyone,

I'm currently working on a scenario involving a remote sensing satellite constellation, and I'm trying to get a good understanding of Figures of Merit in STK. I want to ensure that my coverage definitions are robust and provide meaningful data. Can anyone explain some common Figures of Merit and their applications? Any tips on setting up coverage definitions would also be appreciated!

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Drew Latta posted 7 months ago Admin Best Answer

Great question! Figures of Merit (FOM) are a great tool for evaluating and visualizing data in STK. Here are some common FOMs and their usages:

Simple Coverage: This is the default FOM and measures whether a point was covered by any of the assigned assets. It's a basic but effective way to determine if your coverage area is being observed.
Revisit Time: This FOM measures the intervals during which coverage is not provided, also known as "gaps," for each individual point on your coverage definition. This is very useful for understanding how often a region is imaged and to understand the maximum time you might need to wait for coverage given a certain constellation configuration.
N Asset Coverage: This FOM determines how many different assets are simultaneously covering each individual grid point at each time. It's particularly useful if your mission requires multiple satellites to cover the same area simultaneously.
Percent Coverage: This FOM computes what percent of the area receives coverage by at least one sensor over the specified time period. It's a good way to get a high-level view of your coverage efficiency.
Geometric Dilution of Precision (GDOP) and Navigation Accuracy: These FOM help to determine the certainty of a navigation solution, typically with respect to the GPS constellation, for the grid points in your coverage definition. It's useful to predict the effectiveness of navigation solutions in requiring high positional accuracy.

To get detailed information on each of the individual FOM and how they are calculated, you can find their entries in the STK Help page with the following link:
STK Help: Figures of Merit

To set up a good coverage definition, you should:

Define your Coverage Definition object: This involves setting up the grid and assigning assets.
Insert and configure your FOM objects: Add a FOM to your Coverage Definition object, and set it to the FOM that best suits your mission requirements.
Compute Coverage: Run the coverage analysis to see how well your assets are performing.
Analyze the results: Generate reports, graphs and visualize in STK to evaluate and investigate your results.
- To visualize the value of each FOM in real time, you can go to the FOM’s properties, go to 2D Graphics -> Animation and set Accumulation to “current time,” “up to current time,” etc. If you want, you can also set the FOM to display as a color ramp in the Display Metric section of this page. Then, go to 3D Graphics -> Attributes and disable static graphics so STK only shows you these real time values.
- To generate reports and graphs for these FOM, right click the FOM and open the Report and Graph manager. There are various installed graph/report styles depending on your FOM.

I hope this helps! Let me know if you have any more questions.

Best, Drew

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Drew Latta posted 7 months ago Admin Answer

Great question! Figures of Merit (FOM) are a great tool for evaluating and visualizing data in STK. Here are some common FOMs and their usages:

Simple Coverage: This is the default FOM and measures whether a point was covered by any of the assigned assets. It's a basic but effective way to determine if your coverage area is being observed.
Revisit Time: This FOM measures the intervals during which coverage is not provided, also known as "gaps," for each individual point on your coverage definition. This is very useful for understanding how often a region is imaged and to understand the maximum time you might need to wait for coverage given a certain constellation configuration.
N Asset Coverage: This FOM determines how many different assets are simultaneously covering each individual grid point at each time. It's particularly useful if your mission requires multiple satellites to cover the same area simultaneously.
Percent Coverage: This FOM computes what percent of the area receives coverage by at least one sensor over the specified time period. It's a good way to get a high-level view of your coverage efficiency.
Geometric Dilution of Precision (GDOP) and Navigation Accuracy: These FOM help to determine the certainty of a navigation solution, typically with respect to the GPS constellation, for the grid points in your coverage definition. It's useful to predict the effectiveness of navigation solutions in requiring high positional accuracy.

To get detailed information on each of the individual FOM and how they are calculated, you can find their entries in the STK Help page with the following link:
STK Help: Figures of Merit

To set up a good coverage definition, you should:

Define your Coverage Definition object: This involves setting up the grid and assigning assets.
Insert and configure your FOM objects: Add a FOM to your Coverage Definition object, and set it to the FOM that best suits your mission requirements.
Compute Coverage: Run the coverage analysis to see how well your assets are performing.
Analyze the results: Generate reports, graphs and visualize in STK to evaluate and investigate your results.
- To visualize the value of each FOM in real time, you can go to the FOM’s properties, go to 2D Graphics -> Animation and set Accumulation to “current time,” “up to current time,” etc. If you want, you can also set the FOM to display as a color ramp in the Display Metric section of this page. Then, go to 3D Graphics -> Attributes and disable static graphics so STK only shows you these real time values.
- To generate reports and graphs for these FOM, right click the FOM and open the Report and Graph manager. There are various installed graph/report styles depending on your FOM.

I hope this helps! Let me know if you have any more questions.

Best, Drew

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