Stagnant poses with GEN_3 tracking

Software Python
1

Hello,
I am doing positional tracking GEN_3 on a svo2 file (ZED-X mini @30hz, Orin Nano) from a desktop using pyzed, and noticed that the poses often take several frames to update (see attached screenshots). This obviously leads to unpredictably long windows with unreliable tracking data. This doesn’t occur with enable_imu_fusion = False.
Is this expected behavior or could there be something wrong with the IMU or SVO recording?

sc1
sc11781×784 288 KB

tracking gen_3
tracking gen_31363×799 35.2 KB

2

Hi @ZoharO
What version of the ZED SDK are you using?

3

Hi @ZoharO,
Thanks for the report. Is it possible to get the SVO in order to diagnose the issue on our side ?

Regards,
Tanguy

4

Hi, I’m using version 5.0.5.

5

Hi @TanguyHardelin, I sent a snippet of the SVO to support@stereolabs.com.

6

Hello @ZoharO,

I checked your SVO. It seems to contains a lot of IMU drops. How did you record it ? Is your ZED X driver is up to date ? For recording SVO2 I suggest to use the sample we provide (available at this link).

Your issue is related to this IMU drop. Disabling the IMU fusion give better result. You can disable IMU fusion by setting enable_imu_fusion to false.

Regards,
Tanguy

7

Hello @TanguyHardelin,
Thank you for looking into this.

It was recorded using the ZED Explorer tool with Lossy (jpeg) compression (Orin nano…). I remember having to manually repair the file and believe it was recorded with SDK 5.0.0EA and zed link mono v1.3.0.

Although I stopped getting corrupt files I am still able to replicate the stagnation behavior with the latest SDK 5.0.5 and driver v.1.3.1 when using the ZED_Explorer (JPEG & PNG based compression).

Using the recording sample code (LOSSLESS) instead of the ZED_Explorer (JPEG LOSSY) seems to have an interesting effect - the pose continuously updates between consecutive frames but the frame rate of the drops to from 16 Hz (frame-rate comparable to ZED_Explorer+LOSSLESS png).

Results summary (SDK 5.0.5, driver 1.3.1, HD1200@30):

  • Lossy (ZED_Explorer) → 30 Hz, stagnant poses (~20% of all frames).
  • LOSSLESS (ZED_Explorer) → 16 Hz, stagnant poses (~70% of all frames!!)
  • LOSSLESS (python example) → 16 Hz, no stagnation.

Much appreciated,