OpenCV/Python: Is it possible to change camera properties from Gstreamer, so that the camera doesn't get false positives?

Autonomous Machines Jetson & Embedded Systems Jetson Nano
1

My project has a camera which through opencv tracks 4 laserpoints on a wall.
But when there is low light in the room, the image contains a lot of noise due to the sensitivity.
Is it possible to change the exposure to get rid of the false positives?

I am using Jetson Nano with Rpi2 Camera and Python 3.6 with opencv

def gstreamer_pipeline (capture_width=1280, capture_height=720, display_width=1280, display_height=720, framerate=60, flip_method=0) :   
    return ('nvarguscamerasrc ! '
    'video/x-raw(memory:NVMM), '
    'width=(int)%d, height=(int)%d, '
    'format=(string)NV12, framerate=(fraction)%d/1 ! '
    'nvvidconv flip-method=%d ! '
    'video/x-raw, width=(int)%d, height=(int)%d, format=(string)BGRx ! '
    'videoconvert ! '
    'video/x-raw, format=(string)BGR ! appsink'  % (capture_width,capture_height,framerate,flip_method,display_width,display_height))

cap = cv2.VideoCapture(gstreamer_pipeline(flip_method=0), cv2.CAP_GSTREAMER)
2

Seems auto exposure from ISP is the cause.
You may try to set manual exposure and gains.

3

Thank you!
it worked for me when i executed the command from the link you provided in the terminal

gst-launch-1.0 -e nvarguscamerasrc wbmode=0 awblock=true gainrange="4 4" ispdigitalgainrange="1 1" exposuretimerange="400000 400000" aelock=true ! nvvidconv ! xvimagesink

But how can i implement it to Python?

4

You would change the pipeline creation used for video capture (the function you’ve posted above).
Check this post where a user implemented fixed gains but uses parameter for exposure (note that this case was capturing in I420 format, for your case you would just look at nvarguscamerasrc options).

5

I put it in to the start:

Changed the gain so that the noise disappears completely when there is low light.

Thank you for your help!

def gstreamer_pipeline (capture_width=1280, capture_height=720, display_width=1280, display_height=720, framerate=60, flip_method=0) :   
    return ('nvarguscamerasrc wbmode=0 awblock=true gainrange="1 1" ispdigitalgainrange="1 1" exposuretimerange="5000000 5000000" aelock=true ! '
    'video/x-raw(memory:NVMM), '
    'width=(int)%d, height=(int)%d, '
    'format=(string)NV12, framerate=(fraction)%d/1   ! '
    'nvvidconv flip-method=%d ! '
    'video/x-raw, width=(int)%d, height=(int)%d, format=(string)BGRx ! '
    'videoconvert ! '
    'video/x-raw, format=(string)BGR ! appsink'  % (capture_width,capture_height,framerate,flip_method,display_width,display_height))