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CIGI RateCtrl permanently offsets Entity coordinates


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We just found out that (with at least), RateCtrl permanently offsets an Entity coordinates.

Way to reproduce:

  • create a dummy terrain as a simple plane with geodetic origin at lat/lon/Alt = 0, 0, 0
  • start Hemu and add an ownship at lat/lon/Alt = 0, 0, 1
  • verify the ownship actually appears at 0,0,1 on your dummy terrain
  • with Hemu, send RateCtrl for ownship with Z velocity = -1. The ownship starts to rise. Good.
  • After a few seconds, change the RateCtrl Z velocity to 0 and send one msg. The ownship stops rising up. Good.
  • Send EntityCtrl with a coord lat/lon/Alt = 0, 0, 1 (same as the starting coord). The ownship should go back to the start position, but instead it rises up.

Use case: the RateCtrl is usually used to aid the interpolation in low frequency systems, to help the extrapolation between frames (send  @5Hz a entityctrl along a ratectrl with velocity, while the display is refreshed @60Hz). In the end, if the sending frequency is close to or higher than the display frequency, then the ratectrl should have no effect; but otherwise it can be used as a first order integrator.


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Yes. it looks like a bug.
To reset the local offset, you can use the workaround: set the parent entity, reset the offset relative to the parent, and then remove the parent entity.

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