Extracting data post-run

Development related to the GMAT core and GUI

Extracting data post-run

Postby czalkin » Thu Mar 14, 2013 6:31 pm

Where can I find data about the simulation run after it completes? Does GMAT store the intermediate calculations and data for each step of the simulation or as a function of simulated time? I am interested in converting between known states during the run. For example, I would like to ask some questions in the following form: "At what time did the orbit of the spacecraft passed through the point P in frame M, given that I know that the spacecraft intersected the point?". I would also like to ask "when the spacecraft is at point P, what was it's velocity"? I expect that I would need the first question to answer the second.

If GMAT does not store this level of data, is there a way to request logging or storage of this data?
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Re: Extracting data post-run

Postby jjkparker » Fri Mar 15, 2013 5:24 pm

Are you using GMAT as an end-user, or are you working in the C++ code? I only ask because this is posted to the Core Development forum.

If you're using it as an end-user, maybe we need some more info. If you're looking for info on when a spacecraft passes through a given point, you can use a stopping condition for that, on the Propagate command. You would propagate to that point, then report the time.

Or, you could report an ephemeris (using the EphemerisFile resource), then go back and interpolate the file.

Am I getting close to what you want?
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Re: Extracting data post-run

Postby czalkin » Fri Mar 15, 2013 10:35 pm

This is for c++ development, possibly in a plugin, possibly in our contribution to core.
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Re: Extracting data post-run

Postby jjkparker » Sun Mar 17, 2013 8:33 pm

Ah, I wasn't putting together that this was in reference to the visualization enhancements project. I'll see if any of the devs have advice here.
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Re: Extracting data post-run

Postby jjkparker » Wed Mar 20, 2013 1:08 pm

I believe the short answer is that GMAT does not store any run data as part of its execution, except the data specific to the graphical output. GMAT runs in a "live" mode, where data is generated during execution and is processed immediately. It's not saved, then processed after execution is finished (like STK does it).

Darrel pointed me to the exception for the graphical output:

The ViewCanvas class stores position/velocity data in buffers to support animation of the views after the run has finished.

In src\gui\subscriber\ViewCanvas.hpp:
Code: Select all
   // Space object positions
   Real *mObjectGciPos;            // [mObjectCount][MAX_DATA][3]
   Real *mObjectViewPos;           // [mObjectCount][MAX_DATA][3]
   
   // Space object velocities
   Real *mObjectViewVel;           // [mObjectCount][MAX_DATA][3]


There are other buffers in that file for time, attitude, etc. I imagine that this data is stored in the internal time and coordinate systems (A1 modified Julian, body-centered J2000 inertial frame).
Joel J. K. Parker
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http://gmatcentral.org
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Re: Extracting data post-run

Postby jjkparker » Wed Mar 20, 2013 1:09 pm

Also, it might be helpful to note that GMAT posts its API as Doxygen output, updated every day:
http://gmat.sourceforge.net/docs/

Scroll down to "Developer Documentation".
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Re: Extracting data post-run

Postby czalkin » Wed Mar 20, 2013 2:17 pm

Thanks for the update. I will take a look at these resources.
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Re: Extracting data post-run

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Re: Extracting data post-run

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