Merging two ofVideoGrabbers

beginners
#1

Hi all!

I need to merge two images from two different ofVideoGrabbers. I know that i must use Fbo but i cant get this working. This is what i have;

setup():

fbo.allocate(320, 240);
fbo.begin();
ofClear(255,255,255, 0);
fbo.end();

update():

fbo.begin();  
videoGrabber2.draw(0, 0, 320, 240);  
videoGrabber1.draw(320,0,320,240);  
fbo.end();  

ofTexture tex = fbo.getTextureReference(); // from FBO to Texture  
tex.readToPixels(pix); // from texture to pixels  
colorImg.setFromPixels(pix); // from pixels to ofxCvImage  
colorImg.flagImageChanged(); // update the iplm image 

grayImage = colorImg;	//Convert to grayscale image

draw():

grayImage.draw(0,0);

but nothing appears. Im i missing something important? Thanks!

#2

lets see:

  1. you are allocating the fbo with 320,240 but you are drawing the videoGrabber1 at the position 320 wich its out of fbo size.

    I think you want
    fbo.allocate(640,240);

  2. why are you using a texture??? Seems like you want to pass the fb0 pixels to an ofImage

    ofPixels pxs;
    fbo.readToPixels(pxs);
    colorImg.setFromPixels(pxs);

    if you want to turn colorImg to grayscale
    colorImg.setImageType(OF_IMAGE_GRAYSCALE);

#3

Thanks @pandereto!
Still not getting any image… The webcams are on, i dont have any errros, but no image at all.
On my output window i have this:

[notice] ofFbo: checkGLSupport(): maxColorAttachments: 8, maxDrawBuffers: 8, maxSamples: 4

Any idea?
I need to convert the two videoGrabbers to an ofxCvGrayscaleImage to make some blob detention on it.

#4

You should have more errors in the code, post here the project or a small sample of what its not working (all the code not snippets).

The console output its ok

#5

The errors must be on the fbo part, since everything else is working. But here is my code:

setup():

video.setDeviceID(0);
video.initGrabber(320,240);
	
video2.setDeviceID(1);
video2.initGrabber(320,240);

colorImg.allocate(640, 240);
grayImg.allocate(640, 240);

fbo.allocate(640,240);
fbo.begin();
ofClear(255,255,255, 0);
fbo.end();

update():

video.update();	
video2.update();
    	
if ( video.isFrameNew() ) {

    image.setFromPixels( video.getPixelsRef() );
    image2.setFromPixels( video2.getPixelsRef() );

    fbo.begin();  
    image.draw(0, 0, 320, 240);  
    image2.draw(320,0,320,240);
    fbo.end();  

    ofPixels pxs;
    fbo.readToPixels(pxs);
    colorImg.setFromPixels(pxs);

    grayImg = colorImg;

    if (bLearnBackground == true) {
       grayBg = grayImg;
	   bLearnBackground = false;
	}
	
	grayDiff.absDiff(grayBg, grayImg);

   contourFinder.findContours(grayDiff,minBlobSize, maxBlobSize, blobNum, false);
   blobTracker.trackBlobs(contourFinder.blobs);
}

draw():

grayImg.draw(0,0);
blobTracker.draw(0,240);
#6

can you draw the fbo to see if its right ??

fbo.draw(0,0);`

also not use alpha it don’t need

fbo.allocate(640,240);
fbo.begin();
ofClear(255);
fbo.end();`
#7

I’ve already tried that, and nothing…

#8

what its nothing?

when you draw the fbo can you see something?

#9

omg, sorry!! i had the fbo.draw() inside of an if that i wasnt using (i commented it to try this, so stupid!!).
Ok, it is working!!! thank you so muuuch! Now i have a different problem.

when i have colorImg.draw() or the grayImg.draw(), the image looks like this:

and with the fbo.draw():

Do you know why this is happening?

#10

Ok, problem solved:

setup():

fbo.allocate(640,240, GL_RGB);
fbo.begin();
ofClear(255);
fbo.end();

pix.allocate(640,240, 3);

thanks @pandereto for all the help! :smiley: