how to used extern synchronous triger

Question

Hello, I'm happy to use Azure Kinect and I want to collect synchronous depth data from 8 Azure Kinect and 8 industrial camera.
In order to do this, I design a extern synchronous triger generator to create the synchronous signal.
However, in my test, I find that the synchronous triger seems can only control the start of the acquisition. Even I pulling out the 3.5mm synchronous line, the slave camera is still working.
I suspect there is something wrong with my extern synchronous triger generator, so I observe the synchronous output waveform of the Azure Kinect with an oscilloscopesignal, and use a signal generator to create same waveform as extern synchronous triger signal. But the problem is still exists.
does the camera can not capture every frame synchronously or I forgot some thing need to do ?
Your reply will be appreciated.

Answer 1

I follow the guide in https://learn.microsoft.com/zh-cn/azure/kinect-dk/multi-camera-sync
And I noticed that there is a note in this picture.

sub-device-start
It says that "The camera will not start untill it receives a start singal from the master device". Is that means only the first triger signal make sense?

Answer 2

Hello @志鹏 于 ,

Since you are viewing a slave device, the Azure Kinect Viewer will not display the image after the device has booted.

The image will not be displayed until the slave device receives a sync signal from the master device.

Did you try below steps?

• After starting the slave device, open the master device with another instance of the Azure Kinect Viewer.
• Under External Sync, select Primary.
• Select "Start".

Answer 3

@QuantumCache
hello，thanks for your answer.

I try an experiment as you say:
"After starting the slave device, open the master device with another instance of the Azure Kinect Viewer.
Under External Sync, select Primary.
Select "Start"."

I found that the slave device do start work when I start the master. However, when I stop the master device or pull out the 3.5mm synchronous line, the slave device still work, which means the slave device is not capture with the hardware synchronous triger in frames other than the first frame.

that cause a problem:
when I want to use the 8 Azure Kinect and 8 industrial camera to work together to capture a long sequence, I am not sure if the Azure Kinect still be synchronous to the industrial camera.
As you know, so many camera can't be connect to only one conmputer due to the bandwidth limitation. In fact, I use 4 compute to do this. that means I need to use the extern hardware synchronous triger to make sure every frame was capture at the same time.

Any idea to help me? Thank you very much.

Answer 4

Hello, @QuantumCache , here is the detail infomation of my experience:
step 0 : I connect two Azure Kinect to one computer.

step 1 : I open two device in two Azure Kinect Viewer application, and set one as master, and the other is slave:

step 2 : I start the slave camera, and it don't work, which is right in my opinion

step 3 : Then I start the master camera, and both two camera start to work, which is right in my opinion, too

step 4 : Howerver, when I stop the master camera, even pulling out the 3.5mm synchronous line, the slave camera is still working. That confiused me, In my opinion, the slave camera should capture one times when it received a triger from the master camera, and it shouldn't work without the triger from the master camera.

So, the problem is :
Can the Azure Kinect in slave mode capture each frame Accurately on each triger? A triger is just like clicking the shutter once