[Rock-dev] ROCK loging and dataset creation.

[Evangelos.Boukas at esa.int]

Thanks for your replies Matthias and Sylvain,

I will look into the "estimator" and the "stream aligner". There are two 
main problems that i am tackling here.
1) When data are synchronized (in hardware and ROCK), how can we export 
them with the rock exporter so we create a dataset other devs might want 
to use (rock-independently)?
2) When we have cameras that are hardware synchronized, but we use two 
components ("camera-firewire") to read them, how can we give them exactly 
the same timestamp?

Let's handle the 1st problem. An easy example I have is the following:
The bumblebee stereo camera has a stream containing both left and right 
images so we are sure that the left-right cameras are "hardware 
synchronous":
The bb2 driver deinterlaces the two frames and exports them to the 
appropriate port.. (sorry if the rock terminology is wrong, I'm quite new)

The images are synchronous (obviously because of the camera hardware) and 
the "camera_firewire" orogen component outputs a single message to the 
"camera_bb2" orogen component.
In the "camera_bb2" source you find that:
|       frame_left_ptr->received_time = base::Time::now();
|       frame_right_ptr->received_time = frame_left_ptr->received_time;
So they have the same timestamp assigned to them.

When I log the data and then replay them with the rock replay, I get 
exactly the same times on both "time" and "received_time", in the struct 
viewer, for both cameras.

Then, when I export the images with rock-export  (#TIME prefix) i get two 
images (left right) with the following names:

Loccam_2015_08_28_17_22_23_600342_0.png, with 2015_08_28_17_22_23_600342 
being the timestamp.
Loccam_2015_08_28_17_22_23_601391_2.png, with 2015_08_28_17_22_23_601391 
being the timestamp. (the timastamps differ on a range 2000-3000 
microseconds)

Now, if I understand how the rock-exporter uses some kind of time to 
convert it to the string in the line 118 of 
/log_tools/lib/log_tools/exporter.rb:
|       name.gsub("#TIME",Time.at(rt).strftime("%Y_%m_%d_%H_%M_%S_%6N"))

So, I guess that the problem is in this "rt" from the above code line. It 
seems like it is not one of those that the stream struct has...

Thanks,
Evangelos.


From:   "Sylvain Joyeux" <bir.sylvain at gmail.com>
To:     Evangelos.Boukas at esa.int
Cc:     "rock-dev at dfki.de" <rock-dev at dfki.de>, Rob.Hewitt at esa.int
Date:   09/09/2015 14:53
Subject:        Re: [Rock-dev] ROCK loging and dataset creation.



> Even thought the images are actually synchronised (I can see it from the
> product), the timestamps i am getting are not the same because of the
> aforementioned struct properties.

I am not sure I understand what it means. Can you be more explicit
(like, give an example) ?

Sylvain


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