problem with Snapshot on webcam

Question

muhammad faiz 2017-8-16

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/352887-problem-with-snapshot-on-webcam

回答： ProblemSolver 2023-6-27

Hi everyone, I have problem with the snapshot syntax. so, basically, i have this project which use laser distances and camera/webcam for detection. the process is something like this and it is in real time: when laser sensors detect the obstacles, it will instruct camera to get a snapshot of the scenes. Then, as the laser sensors move closer to the obstacles, it will take another snapshot of the scenes. so, the problem is, i always get similar image between snapshot scenes 2 and snapshot scenes 1. I do not know what happen, seems like the camera stuck in viewing the scenes. The snapshot scenes 2 and Snapshot scenes 1 supposed to be different image due to different distance detected. can somebody tell me what is going on? hope you guys understand the problem.

Thank you

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Image Analyst 2017-8-16

Understood, but there's no way we can fix it. We don't have your code or your laser/camera setup.

muhammad faiz 2017-8-16

在 MATLAB Online 中打开

 end
Radio = serial('COM3','BaudRate',9600); % from the distance sensor
fopen(Radio);
Nvalues=1000000000;
Mvalues=1000000000;
k=0;
w=0;
cam=webcam('ManyCam Virtual Webcam');
cam.Resolution='640x360';
while k<Nvalues
Lidar_distance = fscanf(Radio,'%f');
if (Lidar_distance<=8.1)
    Image_Ref=snapshot(cam);
     while w<Mvalues
             second_distance=fscanf(Radio,'%f');
         if (second_distance<=7.1)
            Image_Current=snapshot(cam);
            break;
         end
         display(second_distance)
         w=w+1;
     end
end
display(Lidar_distance)
k=k+1;
end

______________________ this is my code (simplified version)

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Answer 1

ProblemSolver 2023-6-27

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/352887-problem-with-snapshot-on-webcam#answer_1263493

在 MATLAB Online 中打开

Based on the snippet of the code that you provided:

1) Delay in capturing the second snapshot: It is possible that there is a delay in capturing the second snapshot, causing the camera to capture the same sense as the first snapshot. To address this you can introduce a delay before capturing the snapshot using 'pause' function. For example, you can add 'pause(1)' before capturing 'Image current' to introduce a 1-second delay (Something like this)

if (Lidar_distance <= 8.1)
    Image_Ref = snapshot(cam);
    while w < Mvalues
        second_distance = fscanf(Radio, '%f');
        if (second_distance <= 7.1)
            pause(1); % Add a delay of 1 second
            Image_Current = snapshot(cam);
            break;
        end
        display(second_distance)
        w = w + 1;
    end
end

2) Camera settings or autofocus: The camera settings or autofocus functionality may be affecting the captured images. Ensure that the camera is properly focused and that the autofocus is disabled if it's causing any issues.

3) Image processing issues: If the captured images still appear similar, it could be due to image processing issues. Make sure you are correctly displaying the captured images (Image_Ref and Image_Current) and not accidentally displaying the same image twice.

Additionally, you can print out the image dimensions (size(Image_Ref) and size(Image_Current)) to verify if the images have different dimensions. If they have the same dimensions, it would suggest that the camera is capturing the same scene for both snapshots.

I hope this helps!