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2014-11-25 02:55:15 -0500 commented question OpenCV 2.4.9 + Asus Xtion Pro Live

When you built opencv, did you set the -WITH_OPENNI flag? I had a similar problem when I didn't know that. If not you have to build it again with the right flags set.

It could also be a problem with your openni/primesense version. But since you can launch the viewer that shouldn't be it.

2014-11-25 02:26:40 -0500 asked a question Stereo Vision With Fisheye and FOV camera

Hi,

I have two stereo cameras with different focal length and a baseline of roughly 10cm. I performed an in- and extrinsic calibration using a tool based on Bouguets algorithm under http://www.vision.caltech.edu/bouguetj/calib_doc/

Here are the output I got:

Intrinsic parameters of left camera (HD):

Focal Length:          fc_left = [ 941.65838   941.99357 ] � [ 1.19499   1.55626 ]
Principal point:       cc_left = [ 643.69533   348.60145 ] � [ 1.28309   1.52477 ]
Skew:             alpha_c_left = [ 0.00000 ] � [ 0.00000  ]   => angle of pixel axes = 90.00000 � 0.00000 degrees
Distortion:            kc_left = [ 0.17235   -0.30426   0.00261   0.00016  0.00000 ] � [ 0.00382   0.00795   0.00066   0.00056  0.00000 ]
Pixel error:          err = [ 0.14001   0.15865 ]

Intrinsic parameters of right camera (Wide Angle):

Focal Length:          fc_right = [ 275.62703   275.32800 ] � [ 1.56095   1.91438 ]
Principal point:       cc_right = [ 322.41626   234.36411 ] � [ 2.46595   2.00803 ]
Skew:             alpha_c_right = [ 0.00000 ] � [ 0.00000  ]   => angle of pixel axes = 90.00000 � 0.00000 degrees
Distortion:            kc_right = [ -0.30762   0.11325   -0.00185   -0.00070  0.00000 ] � [ 0.00756   0.00923   0.00092   0.00115  0.00000 ]

Extrinsic parameters (position of right camera wrt left camera):

Rotation vector:             om = [ -0.04394   0.00216  -0.00449 ]

Translation vector:

 T = [ -108.66272   -0.94249  -6.31156 ].

I then put the data into opencvs functions

->stereoRectify( ..., CALIB_USE_INTRINSIC_GUESS, -1 , ... )

->initUndistortRectifyMap()

-> remap(... INNTER_LINEAR) In case you wonder why the fisheye image is still so much distorted at the outer parts, that is because I only calibrated the common viewing area of the two cameras. to get the rectified version of left and right hand side images. Here is what the output looks like: image description image description

When I feed the rectified images then into the Stereo block matcher (StereoBM()) I do do not manage to get a good depth map from that. Also with other images I fail getting good results with this setup. Therefore my questions are:

  1. What can I expect from the rectification? Is that a good result or should the images be aligned with pixel accuracy over the whole scene?
  2. What can I do to get good results for my stereo application - or what are the reasons for the bad performance of my code (Is it possible to combine the Fisheye camera and a "normal" field of view camera in a stereo setup with good results)?
  3. Due to the difference in the focal length and the image size, I can only use a small part of the fisheye image. Any Ideas how I could make the best out of it (e.g. Interpolation with data from right hand side image?)?

Cheers!

2013-11-23 17:44:08 -0500 asked a question OpenCV + QTCreator -> cannot read file from hard disk?

Hi,

I wanted to switch from Code::Blocks to QTCreator after formatting my hard disk. But when I want to use the code I was compiling before without any errors, I now get an errormessage

/usr/include/opencv2/core/operations.hpp:2794: error: no matching function for call to 'read(cv::FileNodeIterator, std::vector<cv::KeyPoint>&)'

when I execute the following:

std::vector<cv::keypoint> key2

cv::FileStorage fs("keypoint.yml", cv::FileStorage::READ);
cv::FileNode  kptFileNode1 = fs["Class1"];
cv::read( kptFileNode1, key2 );
fs.release();

The error is related to the type of the vector, but why did it work before (in Code::Blocks) and how can I fix this? I'm using ubuntu 12.04 with opencv-2.4.7 and Qt Creator 2.4.1 .

Thanks for helping.