triangulate 3d points from stereo images?

asked 2015-06-11 16:19:12 -0500

stillNovice gravatar image

updated 2015-06-12 06:37:33 -0500

I have a stereo pair of images, downloaded from a dataset along with the camera calibration data.

I am using the camera projection matrices, which look like this:

6.452401 0.000000 6.359587 0.000000 
0.000000 6.452401 1.941291 0.000000
0.000000 0.000000 1.000000 0.000000

6.452401 0.000000 6.359587 -3.682632 
0.000000 6.452401 1.941291 0.000000 
0.000000 0.000000 1.000000 0.000000

I have feature matched keypoints on both frames, which I then run through triangulatepoints, like this:

vector<cv::Point2f> points2dLeft, points2dRight;

cv::Mat points_3D(1, 5, CV_64FC4);

for (std::vector<cv::DMatch>::const_iterator it = good_matches.begin(); it != good_matches.end(); ++it)

    float x = keypoints1[it->queryIdx].pt.x;
    float y = keypoints1[it->queryIdx].pt.y;
    points2dLeft.push_back(cv::Point2f(x, y));

    x = keypoints2[it->trainIdx].pt.x;
    y = keypoints2[it->trainIdx].pt.y;
    points2dRight.push_back(cv::Point2f(x, y));

cv::triangulatePoints(P1, P2, points2dLeft2, points2dRight2, points_3D);

These are the 2d points:

and this is the camera data:

I have also tried the method here:

which gives different,, but just as awful results. Has anyone successfully done this and created an accurate point cloud?

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There are so many factors playing. How good is your calibration? How much inliers/outliers at your keypoints, ... give us actual data that you use and we might be able to say something good.

StevenPuttemans gravatar imageStevenPuttemans ( 2015-06-12 06:10:13 -0500 )edit

Hi, thanks for replying. I am using the calibration file that came with the dataset, it should be as accurate as is possible. I am using SURF to get features, BM matcher and then RANSAC to remove outliers. The points I feed to the triangulation SHOULD be corresponding, right? I have updated my question with more info, including the 2d points that I am getting.

stillNovice gravatar imagestillNovice ( 2015-06-12 06:33:54 -0500 )edit

Any update on this?

Can you tell me why did you choose to insert negative value for translation in your projection matrix (-3.682632 )?

acajic gravatar imageacajic ( 2015-10-01 06:39:37 -0500 )edit