Poor OpenCV camera resolution

Eyecandy

Poor OpenCV camera resolution

in Contributed Library Questions • 3 years ago

Hello out there,
i'm experimenting with OpenCv - Blob Tracking.
OpenCv provides only 320*240 resolution - i get 640*480 out of Jmyron. I just tried to capture with GSVideo which delivered blazing 1600*1200.
Does anybody know how to get OpenCv to analyse pictures from GSVideo for example? I also dont know if i really need this high resolutions. I plan to track persons from above - so a few more pixels than 320*240 are needed (1600 is perhaps oversized ;) ). For further reasons it would be really cool if i can stich the pictures of 2 or 4 cams and let OpenCv search blobs in the stiched one.

Anybody ideas?
Kind regards

eyecandy

Replies(4)

cedrickie..

Re: Poor OpenCV camera resolution

3 years ago

you dont need a high resolution for blob tracking. 1600x1200 is way to much.
i dont know how large the area is that you want to track, but 320x240 might already be enough...

btw, maybe also have a look at flob, another blob detection library
http://s373.net/code/flob/flob.html

Eyecandy

Re: Re: Poor OpenCV camera resolution

3 years ago

Hi!
Thank you for the information!
In example the area to track is 320 cm * 240 cm (because its easy to calc

) i have 1 pixel per cm². So a person tracked from above would be approx. 40*20 pixels in the picture... (just messing around with a ruler around my head/shoulders

). I will experiment a little bit. Thanks to color correction/image subtraction the result is really cool so far!
However the problem of multiple cameras - image stiching persists....

This is a hand in hand problem with the resolution...assuming that a resolution of 1 pixel per cm² allows stable tracking, i can track only 320cm * 240cm. With a higher resolution i modify the camera (higher position/another lens) to shoot a larger area - and perhaps eliminate the multiple camera and stiching problem. 800*600 'd be 8 to 6 meters - somewhat better than 3 to 2.

Flob looks interesting btw! I will get into it the next few hours... Perhaps it takes pictures from GSV...

Eyecandy

Re: Poor OpenCV camera resolution

3 years ago

I managed to feed OpenCV with pictures from GSVideo, giving me the ability to use nice OpenCV functions with a great resolution.

import hypermedia.video.*;
import codeanticode.gsvideo.*;
import java.awt.*;

OpenCV opencv;
GSCapture cam;

int w = 800;
int h = 600;
int framerate = 60;
int threshold = 80;

boolean find=true;

PFont font;

void setup() {

    size( w*2+30, h*2+30 );





    opencv = new OpenCV( this );
    //opencv.capture(w,h);

    //My cam should be listed - otherwise GSVideo lib probably not working
    String[] cameras = GSCapture.list();

    if (cameras.length == 0)
    {
        println("There are no cameras available for capture.");
        exit();
      } else {
        println("Available cameras:");
        for (int i = 0; i < cameras.length; i++)
          println(cameras[i]);
        cam = new GSCapture(this, w, h, cameras[0]);
        cam.frameRate(framerate);
      }
      //Get some space for our own Image
      opencv.allocate(w,h);

      font = loadFont( "AndaleMono.vlw" );
      textFont( font );

      println( "Drag mouse inside sketch window to change threshold" );
      println( "Press space bar to record background image" );

}

void draw() {
    if (cam.available() == true) {

        background(0);
        //don't read - load from other cam
        //opencv.read();
        cam.read();
        opencv.copy(cam);

        //opencv.flip( OpenCV.FLIP_HORIZONTAL );

        image( opencv.image(), 10, 10 );                // RGB image
        image( opencv.image(OpenCV.GRAY), 20+w, 10 );   // GRAY image
        image( opencv.image(OpenCV.MEMORY), 10, 20+h ); // image in memory

        opencv.absDiff();
        opencv.threshold(threshold);
        image( opencv.image(OpenCV.GRAY), 20+w, 20+h ); // absolute difference image


        // working with blobs
        Blob[] blobs = opencv.blobs( 100, w*h/3, 20, true );

        noFill();

        pushMatrix();
        translate(20+w,20+h);

        for( int i=0; i<blobs.length; i++ ) {

            Rectangle bounding_rect    = blobs[i].rectangle;
            float area = blobs[i].area;
            float circumference = blobs[i].length;
            Point centroid = blobs[i].centroid;
            Point[] points = blobs[i].points;

            // rectangle
            noFill();
            stroke( blobs[i].isHole ? 128 : 64 );
            rect( bounding_rect.x, bounding_rect.y, bounding_rect.width, bounding_rect.height );


            // centroid
            stroke(0,0,255);
            line( centroid.x-5, centroid.y, centroid.x+5, centroid.y );
            line( centroid.x, centroid.y-5, centroid.x, centroid.y+5 );
            noStroke();
            fill(0,0,255);
            text( area,centroid.x+5, centroid.y+5 );


            fill(255,0,255,64);
            stroke(255,0,255);
            if ( points.length>0 ) {
                beginShape();
                for( int j=0; j<points.length; j++ ) {
                    vertex( points[j].x, points[j].y );
                }
                endShape(CLOSE);
            }

            noStroke();
            fill(255,0,255);
            text( circumference, centroid.x+5, centroid.y+15 );

        }
        popMatrix();

}

}

void keyPressed() {
    if ( key==' ' ) opencv.remember();
}

void mouseDragged() {
    threshold = int( map(mouseX,0,width,0,255) );
}

public void stop() {
    opencv.stop();
    super.stop();

It is roughly copied together - but working!
The main problem now is a bug in GSVideo - Link

den2themo..

Re: Re: Poor OpenCV camera resolution

3 years ago

Hi! I tested your code, but found a bug!...

Until I use "Blob[] blobs = opencv.blobs( 100, w*h/3, 20, true );" all is going ok. opencv.image(); is colour RGB, and remember function works correctly.

BUT, when I include this line "Blob[] blobs = opencv.blobs( 100, w*h/3, 20, true );", code is going crazy!

0) actually, it's because of opencv.blobs(); function exactly... I can't find solution on forums..
1) opencv.image() gimme grayscaled image
2) remember() function doesnot work anymore...

when I use opencv.remember(); or opencv.remember(OpenCV.SOURCE); , memory image is black! only one pixel in first line of image is pink (hmm..)

if I use opencv.remember(OpenCV.BUFFER); - I get some strange picture, white pixels on the edges of contrast shapes...

So, I can't use absDiff(); function correctly too because of this bug...
Can you help me?

p.s. I use: windows XP SP3, processing 1.2.1, opencv 1.0, gsvideo 0.4.5-win

p.p.s. Usage of opencv.capture instead of GSCapture gimme workable functions, RGB image, but verrry slow framerate...

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