Hardware trigger synchronization including RGB image (Oakd-s2)

toon

I am trying to trigger my Oakd-s2 (AF) on ubuntu24 with the example provided here.

https://gist.github.com/Erol444/0138af63378dc8de5b3f7d80db1ea1a5

I managed to get this script working, however, the RGB image is not shown. In the following thread, https://discuss.luxonis.com/d/2304-multiple-oak-ffc-4p-based-cameras-timestamp-sync/5 it was said that they got the trigger working included RGB image, unfortunately any example is missing. Could this be shared?

jakaskerl

toon
You are using an external trigger right?

The code is meant for OAK-FFC (or POE M8) devices where the FSIN is exposed. This is not possible on S2 unless you open it and connect it to a FSIN line (which is not easily accessible).

Thanks,
Jaka

erik

@toon RGB camera won't work because the sensor doesn't support "snapshot" triggering, only "continuous" triggering at a very fixed intervals (eg. 30.00Hz). Pleas see link below for details:
https://docs.luxonis.com/hardware/platform/deploy/frame-sync/#Sensor%20FSYNC%20support
Thanks, Erik

toon

jakaskerl sorry for the misconfusion, I am using a OAK-D S2 PoE with autofocus, so I have already implemented the M8 connector.

What I would like to do is to trigger multiple devices (3) with a external trigger pulse. Furthermore I want to output an rgb image as close as possible with the triggered mono-images, but they don't have to be fully hardware synchronised.

jakaskerl

toon
Then the code is fine, just set the color camera FPS to the exactly the same FPS at which you are triggering the other two cameras. As Erik said, snapshot mode does not work.

Continuous streaming with external syncing, configured with CameraControl.setFrameSyncMode(). In this mode, the FSIN signal is expected to arrive at a continuous rate matching the configured sensor FPS, and trigger can't arrive at arbitrary times as that would disrupt internal sensor operations (leading to bad frames, etc). It can only correct for very small amounts of drift over time.

Thanks,
Jaka

jakaskerl

toon
You need to trigger at exactly 30Hz for this to work. as mentioned in jakaskerl

toon

Dear Jakaskerl,

Indeed the color camera in following script does not work example.

Instead I wrote the following script including sync node, but still I do not get an image, what am I doing wrong?

#!/usr/bin/env python3
import depthai as dai
import cv2
import time
from datetime import timedelta

# FPS_tof = 10
FPS_rgb = 10
with_trigger = True


pipeline = dai.Pipeline()

# RGB camera
camRgb = pipeline.create(dai.node.ColorCamera)
camRgb.setColorOrder(dai.ColorCameraProperties.ColorOrder.RGB)
camRgb.setIspScale(2, 3)
camRgb.setBoardSocket(dai.CameraBoardSocket.RGB)
camRgb.setFps(FPS_rgb)
if with_trigger:
    camRgb.initialControl.setFrameSyncMode(dai.CameraControl.FrameSyncMode.INPUT)
    camRgb.initialControl.setExternalTrigger(4, 3)


xout = pipeline.create(dai.node.XLinkOut)
xout.setStreamName("out")
# camRgb.isp.link(xout.input)  # Link the RGB output to XLinkOut

# Mono left camera
monoLeft = pipeline.create(dai.node.MonoCamera)
monoLeft.setResolution(dai.MonoCameraProperties.SensorResolution.THE_720_P)
monoLeft.setBoardSocket(dai.CameraBoardSocket.LEFT)
monoLeft.setFps(FPS_rgb)
if with_trigger:
    monoLeft.initialControl.setFrameSyncMode(dai.CameraControl.FrameSyncMode.INPUT)
    monoLeft.initialControl.setExternalTrigger(4, 3)

# Mono right camera
monoRight = pipeline.create(dai.node.MonoCamera)
monoRight.setResolution(dai.MonoCameraProperties.SensorResolution.THE_720_P)
monoRight.setBoardSocket(dai.CameraBoardSocket.RIGHT)
monoRight.setFps(FPS_rgb)
if with_trigger:
    monoRight.initialControl.setFrameSyncMode(dai.CameraControl.FrameSyncMode.INPUT)
    monoRight.initialControl.setExternalTrigger(4, 3)

xoutRight = pipeline.create(dai.node.XLinkOut)
xoutRight.setStreamName("right")
monoRight.out.link(xoutRight.input)

# Sync node (if you want to sync all cameras)
sync = pipeline.create(dai.node.Sync)
# sync.setSyncThreshold(50)  # Sync threshold in milliseconds
sync.setSyncThreshold(timedelta(milliseconds=1000))

# Linking RGB, left, and right to the sync node
camRgb.isp.link(sync.inputs["color"])  # Link RGB to sync
monoLeft.out.link(sync.inputs["left"])
monoRight.out.link(sync.inputs["right"])

# You can link the sync output to XLinkOut for all cameras
sync.out.link(xout.input)
# sync.out.link(xoutLeft.input)
# sync.out.link(xoutRight.input)

# Device connection
device_id = "169.254.1.103"
with dai.Device(pipeline, dai.DeviceInfo(device_id)) as device:

    queue = device.getOutputQueue("out", 8, False)
    queueright=device.getOutputQueue("right")

    print("Starting...", queue)
    while True:
        # if queueright["right"].has():
        #     test=queueright["right"].get().getCvFrame()
        #     print("x")
        messageGroup: dai.MessageGroup = queue.get()
        frameMono_right: dai.ImgFrame = messageGroup["right"]
        frameMono_left: dai.ImgFrame = messageGroup["left"]
        # frameDepth_tof: dai.ImgFrame = messageGroup["depth_tof"]
        frameRgb: dai.ImgFrame = messageGroup["color"]
        # Blend when both received
        if frameMono_right is not None:
            if frameRgb is not None:
                print(frameMono_right.getSequenceNum())
                print(frameRgb.getSequenceNum())
                # print(messageGroup["depth"].getTimestamp()-messageGroup["rgb"].getTimestamp())
                # print(messageGroup["rgb"].getSequenceNum())
                # print(messageGroup["depth"].getSequenceNum())
                monoRight_img = frameMono_right.getCvFrame()
                # # cv2.imshow("rgb", frameRgb)
                # # cv2.imshow("depth", colorizeDepth(frameDepth.getCvFrame()))
                test=frameRgb.getCvFrame()
                print("It is working")
            else:
                print("no depth frame")
        else:
            print("no rgb frame")

        key = cv2.waitKey(1)
        if key == ord("q"):
            break


cv2.destroyAllWindows()

jakaskerl

toon
How does the trigger signal look?

Thanks,
Jaka

toon

The trigger signal is just a signal triggered by a pushbutton (for test and verification). Same setup as in externally trigger fsync. In the end we would like to trigger with a PLC based on the encoder value (every x cm).

toon

Ok, so if I understand correctly, there is no way to hardware-trigger the stereo frames and then find the most close rgb-frame softwarematticaly (even if we leave it streaming at 30FPS)?

jakaskerl

toon
Correct, the frame triggers are expected (by IMX378) to come at a fixed rate. The issue is the the fsin lines are connected together and only triggering the OV strereo cameras wouldn't work. If the lines were separate this should be possible.

RGB will not stream if both left and right are set to input mode.

Thanks,
Jaka