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missing region in disparity map

asked 2012-09-17 07:45:58 -0500

m47h gravatar image

i am currently working on stereo processing using opencv2.3 and a Pointgrey Bumblebee2 stereocamera as an input device. Acquiring images is done via the libdc1394.

My code for rectification and stereo processing is the following:

void StereoProcessing::calculateDisparityMap(const Mat &left, const Mat &right, Mat &disparity_map)

  Mat map11, map12, map21, map22, left_rectified, right_rectified, disp16;

  // Computes the undistortion and rectification transformation maps
  initUndistortRectifyMap(this->camera_matrix1,
        this->distance_coefficients1,
        this->R1,
        this->P1,
        this->output_image_size,
        CV_16SC2,
        map11,
        map12);
  initUndistortRectifyMap(this->camera_matrix2,
        this->distance_coefficients2,
        this->R2,
        this->P2,
        this->output_image_size,
        CV_16SC2,
        map21,
        map22);

  // creates rectified images
  remap(left, left_rectified, map11, map12, INTER_LINEAR);
  remap(right, right_rectified, map21, map22, INTER_LINEAR);

  // calculates 16-bit disparitymap
  this->stereo_bm(left_temp, right_temp, disp16);

  disp16.convertTo(disparity_map, CV_8U, 255 / (this->stereo_bm.state->numberOfDisparities * 16.0));
}

This works fine except for a black left border in the disparity map, which is the following:

image description

The input images are these two - unrectified as you can see ;) :

image description image description

So my question is now: Is this normal behaviour? Or do you see any mistake i have done so far? As another information, the rectification works fine.

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answered 2012-09-18 02:54:58 -0500

Jacek gravatar image

I think it's a normal behaviour that region with x-coordinates between 0 and max_disparity is not reconstructed.

Suppose on a rectified left image you have a point with x-coordinate x0, where 0 < x0 < max_disparity. Potential matches for this point on the right rectified image have x-coordinate in < x0-max_disparity; x0 > range. But if x0 < max_disparity part of this range has negative x-coordinate and is not visible on the rectified right image. So disparity cannot be calculated.

And one advice: for better results use StereoSGBM algorithm. It usually gives much better results than simple block matching (StereoBM) algorithm.

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Is there any way to solve this problem using the StereoBM Algorithm

KarimO gravatar imageKarimO ( 2014-03-14 08:57:24 -0500 )edit
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Asked: 2012-09-17 07:45:58 -0500

Seen: 877 times

Last updated: Sep 18 '12