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Replays of helicopter flights look weird

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Revision as of 07:23, 20 August 2019 by Johan G (Talk | contribs) (+- Minor cleanup; cat: Howto)

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When recording and replaying helicopter flights with the new flight recorder, the replay looks weird. The flight path appears to seem edgy and the helicopter performs maneuvers which are physically impossible.

Reason

The new flight recorder in it's default configuration only records the last 60 seconds of the flight in full data resolution. Everything older is stored in a compressed format and interpolated during replay, which leads to unnatural motion patterns of helicopters in the replay before the last 60 seconds.

Solution

Change the configuration of the flight recorder in preferences.xml to keep a bigger amount of data uncompressed.

Caveats

Uncompressed data takes more memory than compressed data. As an example, the BK117 requires about 1MB per minute of uncompressed data recording.

Example

This example extends the uncompressed recording time to 10 minutes and the medium compression time to 30 minutes.

		<replay>
			<duration type="double">90</duration>
			<view type="int">1</view>
			<looped type="bool" userarchive="y">true</looped>
			<buffer> <!-- replay buffer configuration -->
				<!-- 1st buffer level: short term -->
				<high-res-time type="double">600</high-res-time> <!-- 60 seconds -->
				<!-- short term sample rate is as every frame (fixed) -->
				<!-- 2nd buffer level: medium term -->
				<medium-res-sample-dt type="double">0.5</medium-res-sample-dt>
				<medium-res-time type="double">1800</medium-res-time><!-- 10 mins -->
				<!-- 3rd buffer level: long term -->
				<low-res-sample-dt type="double">5.0</low-res-sample-dt>
				<low-res-time type="double">3600.0</low-res-time><!-- 1 h -->
			</buffer>
		</replay>

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