Zed-ros-wrapper: If there any way to obtain the real time-stamp when the image was shot?

[JeyP4]

Hi
I think the time stamp attach to the topic '/rgb/image_rect_color/compressed' indicates the time when it was published in the ROS network.

Is there any way to obtain the time-stamp of when actually the frame was captured? (aside of placing a physical clock in front of camera)

Sorry for this non-trivial question..

Thanks

[Myzhar]

Hi @JeyP4,
the timestamp of each image is the time when the frame is grabbed by the ZED SDK, retrieved using this functionwithTIME_REFERENCE_IMAGE` as parameter:
https://github.com/stereolabs/zed-ros-wrapper/blob/6f0e1a5b6b52574bb5c8865ac493d780c365a9db/zed_wrapper/src/nodelet/src/zed_wrapper_nodelet.cpp#L1780

The only thing of which I'm not sure is about how image_transport works when it creates the compressed image.
What you can do is to check if /rgb/image_rect_color/compressed and /rgb/image_rect_color have the same timestamp.

[JeyP4]

Hi
Thanks for your comment.

1. Timestamp of /rgb/image_rect_color & /rgb/image_rect_color/compressed both are exactly same. (I checked)

2. At VGA 30 fps, I observe that timestamp is actually delayed by 1-2 frames. I.e., suppose in reality frame is captured at time 0.000 sec, timestamp of the frame is ~0.060 sec.

So I am thinking is it anyway possible to obtain real timestamp with adequate accuracy?

My PC specs are : GeForce GTX 1050 Ti
Intel i7
128 GB RAM

[Myzhar]

@JeyP4 I'm checking with the HW team to give you the right reply

[JeyP4]

Hello @Myzhar

Did you get any reply from the HW team!

[JeyP4]

Dear @Myzhar
Please help!!

[obraun-sl]

Hi,
With the current version, you can consider the delay between the camera timestamp and the real timestamp at the time the frame was captured on the sensor to be about 3 frames. However it can vary a bit.

We are working for the next version on a more accurate timestamp where the delay between the USB capture timestamp and the "shutter time" timestamp is more accurate and fixed.

Best,
OB.

[JeyP4]

Thanks @obraun-sl
Waiting for the next version. Hope to see it soon..

[JeyP4]

When is the new SDK version coming?
Any estimation!!

[WASCHMASCHINE]

We are also waiting for the new SDK version!

[JeyP4]

Hey guys,
Any indication of new SDK?