# Obtaining underwater motion paths question
**URL:** https://discuss.bluerobotics.com/t/obtaining-underwater-motion-paths-question/14091
**Category:** General Discussion
**Created:** [April 11, 2023, 11:37am UTC](https://discuss.bluerobotics.com/t/obtaining-underwater-motion-paths-question/14091 "2023-04-11T11:37:22Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@suitangxiaoyi](https://discuss.bluerobotics.com/u/suitangxiaoyi)
#### Post date: [April 11, 2023, 11:37am UTC](https://discuss.bluerobotics.com/t/obtaining-underwater-motion-paths-question/14091/1 "2023-04-11T11:37:22Z")
How can I use the QGC log file to calculate the path of Blue ROV2 running in the water?I tried looking for this variable in the log but couldn’t find it.
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### Author:  [@EliotBR](https://discuss.bluerobotics.com/u/EliotBR)
#### Post date: [April 11, 2023, 8:08pm UTC](https://discuss.bluerobotics.com/t/obtaining-underwater-motion-paths-question/14091/2 "2023-04-11T20:08:15Z")
Hi @suitangxiaoyi,
If your vehicle has a positioning estimate then that should be available in QGC’s `.tlog` telemetry files in the [`GLOBAL_POSITION_INT`](https://mavlink.io/en/messages/common.html#GLOBAL_POSITION_INT) messages. If you’re using QGC to download `.bin` log files off the flight controller I believe the relevant onboard (autopilot) message is [`POS`](https://ardupilot.org/copter/docs/logmessages.html#pos), but the [`GPS`](https://ardupilot.org/copter/docs/logmessages.html#gps) and [`VISP`](https://ardupilot.org/copter/docs/logmessages.html#visp) messages might also be useful if you want to see the data being provided by your GPS or DVL.
If your vehicle doesn’t have a positioning estimate then the log file will not include the path, because it doesn’t know where it is or where it’s gone. You could try to calculate a relative path (from the starting point of the dive) by correcting the accelerometer values for attitude and doubly integrating, but that would only give you a rough _shape_ of the path (without accurate distances), because the IMU sensor errors are too significant to be used for position estimation without some form of external correction.
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### Author:  [@suitangxiaoyi](https://discuss.bluerobotics.com/u/suitangxiaoyi)
#### Post date: [April 12, 2023, 1:13pm UTC](https://discuss.bluerobotics.com/t/obtaining-underwater-motion-paths-question/14091/3 "2023-04-12T13:13:25Z")
Thanks for your help.