Taking still images in the dark (using IR flood and monoCamera)

criclabs

Hi,

We have HTTP servers setup on 16 cameras in the lab, serving RGB still images.
This works great and integrate into our infrastructure perfectly.

Is there a way to allow us to capture still images in full darkness, using the IR flood LEDs and the monoCameras ?
Ideally we would only lit up the IR LED for the duration of the still capture to disturb the experiments the least possible and spare the camera so we dont have the IR running 24/7.

We are using OAK-D Pro W PoE and OAK-D Pro PoE
Thank you very much !

Simon

jakaskerl

Hi criclabs
The mono camera doesn't have the capability to output a "still" image. This means the mono camera will have to run continuously. But, the Device.setIrFloodLightBrightness() can be called from both, the host side or the script node. This way you can manually turn on the LED for a short duration and turn it off after, so it doesn't consume additional current.

https://docs.luxonis.com/projects/api/en/latest/samples/MonoCamera/mono_preview_alternate_pro/

Thanks,
Jaka

criclabs

Hi Jakaskerl,

Thank you for your response! Would it be a problem if the mono run non stop 24/7 for weeks?
Would you have some pointers of how we should approach taking stills trough the videofeed ? Would it have to happen on our local server, or its something that is possible for the camera to produce and upload or something.

Many thanks in advance,
Simon

jakaskerl

criclabs Thank you for your response! Would it be a problem if the mono run non stop 24/7 for weeks?

In terms of hardware, no. In terms of stability.., I'm not sure how the device would behave after running constantly for weeks at a time. You could use the script node and send a message to the device each time you wish to take a still image. In the meanwhile, the script node would ignore the frames coming in. Only when receiving the flag, should it turn on the floodlight and output the frame that was currently in queue.

Thanks,
Jaka

criclabs

Great, I will check for this approach through the exemples!
To my understanding so far, the mono cameras don't allow for the same 'Still' capture methods as the RGB ones, right ?

Could you elaborate a little bit on how this works to capture de feed of the frame for those?

Thank you for your support.
Simon

jakaskerl

Hi criclabs
No, mono cameras do not have a still output. There is an option to use the external trigger (explained here).

I found a better example, essentially using the GPIO pins to take mono still images when pressing "c":

#!/usr/bin/env python3
import depthai as dai
import cv2
import time
 
pipeline = dai.Pipeline()
 
 

monoLeft = pipeline.create(dai.node.MonoCamera)
monoLeft.setResolution(dai.MonoCameraProperties.SensorResolution.THE_720_P)
monoLeft.setBoardSocket(dai.CameraBoardSocket.LEFT)
monoLeft.initialControl.setFrameSyncMode(dai.CameraControl.FrameSyncMode.INPUT)
monoLeft.initialControl.setExternalTrigger(4,3)
 
xoutLeft = pipeline.create(dai.node.XLinkOut)
xoutLeft.setStreamName("left")
monoLeft.out.link(xoutLeft.input)
 
monoRight = pipeline.createMonoCamera()
monoRight.setResolution(dai.MonoCameraProperties.SensorResolution.THE_720_P)
monoRight.setBoardSocket(dai.CameraBoardSocket.RIGHT)
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)
 
xin = pipeline.create(dai.node.XLinkIn)
xin.setStreamName('in')
script = pipeline.create(dai.node.Script)
xin.out.link(script.inputs['in'])
script.setScript("""
import GPIO
import time
GPIO_PIN=41 # Trigger
 
GPIO.setup(GPIO_PIN, GPIO.OUT, GPIO.PULL_DOWN)
 
def capture():
    GPIO.write(GPIO_PIN, True)
    time.sleep(0.001) # 1ms pulse is enough
    GPIO.write(GPIO_PIN, False)
 
while True:
    
    wait_for_trigger = node.io['in'].get()
    capture()
    node.warn('Trigger successful')
""")
 
 
xout = pipeline.create(dai.node.XLinkOut)
xout.setStreamName('out')
script.outputs['out'].link(xout.input)
 
# Connect to device with pipeline
with dai.Device(pipeline) as device:
    inQ = device.getInputQueue("in")
 
    arr = ['left', 'right']
    queues = {}
    frames = {}
 
    for name in arr:
        queues[name] = device.getOutputQueue(name)
 
    def trigger():
        buffer = dai.Buffer()
        buffer.setData([1])
        inQ.send(buffer)
 
    time.sleep(1)
    trigger() # Inital trigger
 
    while True:
        for name in arr:
            if queues[name].has():
                frames[name]=queues[name].get().getCvFrame()
 
        for name, frame in frames.items():
            cv2.imshow(name, frame)
 
        key = cv2.waitKey(1)
        if key == ord('q'):
            break
        elif key == ord('c'):
            trigger()

Hope this solves your issue.

Thanks,
Jaka

criclabs

Thank you for you quick answer, I will work with that and see what we can incorporate !