Comments on: 3D Vision with Stereo Disparity http://www.shawnlankton.com/2007/12/3d-vision-with-stereo-disparity/ computer vision, science, business, and life Sun, 14 Mar 2010 10:53:07 -0400 http://wordpress.org/?v=2.8 hourly 1 By: Ray Phan http://www.shawnlankton.com/2007/12/3d-vision-with-stereo-disparity/comment-page-1/#comment-1274 Ray Phan Wed, 03 Feb 2010 16:55:26 +0000 http://www.shawnlankton.com/2007/12/3d-vision-with-stereo-disparity/#comment-1274 <a href="#comment-1270" rel="nofollow">@emy </a> I'm running MATLAB 7.8.0 (R2009a) and the function exists in my version... you probably have an outdated version of MATLAB. I know R14 was a version of MATLAB as of around 2005. I kept on getting run-time errors and it wouldn't start when I tried installing it on my PC! Try typing in help im2single to see if the function exists for you. The function converts the image to single precision. When you run mex -setup, make sure you choose either the Microsoft Visual C++ compiler in Windows, gcc in Linux, or mexopts in the MACOSX environment. Their default compiler doesn't seem to work very well. As for 3DView, I'm not too familiar with it. What is it supposed to do? @emy

I’m running MATLAB 7.8.0 (R2009a) and the function exists in my version… you probably have an outdated version of MATLAB. I know R14 was a version of MATLAB as of around 2005. I kept on getting run-time errors and it wouldn’t start when I tried installing it on my PC! Try typing in help im2single to see if the function exists for you. The function converts the image to single precision.

When you run mex -setup, make sure you choose either the Microsoft Visual C++ compiler in Windows, gcc in Linux, or mexopts in the MACOSX environment. Their default compiler doesn’t seem to work very well.

As for 3DView, I’m not too familiar with it. What is it supposed to do?

]]> By: emy http://www.shawnlankton.com/2007/12/3d-vision-with-stereo-disparity/comment-page-1/#comment-1270 emy Mon, 01 Feb 2010 12:57:05 +0000 http://www.shawnlankton.com/2007/12/3d-vision-with-stereo-disparity/#comment-1270 have you idea about 3d view using matlab? have you idea about 3d view using matlab?

]]> By: emy http://www.shawnlankton.com/2007/12/3d-vision-with-stereo-disparity/comment-page-1/#comment-1267 emy Sat, 30 Jan 2010 14:38:23 +0000 http://www.shawnlankton.com/2007/12/3d-vision-with-stereo-disparity/#comment-1267 @ Ray thank you so much about your interesting and your answers i goto Shai Bagon’s website and download the MATLAB wrapper but some functions undefind like featurefun , im2single so, i have many error i'm using MATLAB Version 7.0.0.19920 (R14), can you help me?? and i have another problem i can't deal with mex after setup!!!!! regards emy @ Ray
thank you so much about your interesting and your answers
i goto Shai Bagon’s website and download the MATLAB wrapper but some functions undefind like featurefun , im2single so, i have many error i’m using MATLAB Version 7.0.0.19920 (R14), can you help me??
and i have another problem i can’t deal with mex after setup!!!!!
regards
emy

]]> By: Ray Phan http://www.shawnlankton.com/2007/12/3d-vision-with-stereo-disparity/comment-page-1/#comment-1261 Ray Phan Fri, 29 Jan 2010 01:04:29 +0000 http://www.shawnlankton.com/2007/12/3d-vision-with-stereo-disparity/#comment-1261 <a href="#comment-1259" rel="nofollow">@emy </a> That dissimilarity is inspired by the Klaus, Sormann and Karner paper. They use a combination of sum of absolute differences, and gradient features to produce reliable disparities. The SAD measure is good if you assume that the surface is Lambertian, and the gradient features are good for surfaces that aren't subject to Lambertian properties, but they have poor discriminating power. So these authors combined both of these similarity measures together to produce a final dissimilarity function, and they use local matching methods with this function to compute a disparity map. Some of the things in the paper that are key elements to the algorithm they conveniently left out... such as the disparity plane fitting. There's a lot more math going on than in those two paragraphs they wrote, and it's kind of disconcerting that they left it out. Also, the mean-shift code is there. You have to go to Shai Bagon's website and download the MATLAB wrapper. Shawn didn't implement the code, but used the MATLAB wrapper instead. He also wrote a wrapper on top of the wrapper to make things easier. - Ray. @emy

That dissimilarity is inspired by the Klaus, Sormann and Karner paper. They use a combination of sum of absolute differences, and gradient features to produce reliable disparities. The SAD measure is good if you assume that the surface is Lambertian, and the gradient features are good for surfaces that aren’t subject to Lambertian properties, but they have poor discriminating power. So these authors combined both of these similarity measures together to produce a final dissimilarity function, and they use local matching methods with this function to compute a disparity map.

Some of the things in the paper that are key elements to the algorithm they conveniently left out… such as the disparity plane fitting. There’s a lot more math going on than in those two paragraphs they wrote, and it’s kind of disconcerting that they left it out.

Also, the mean-shift code is there. You have to go to Shai Bagon’s website and download the MATLAB wrapper. Shawn didn’t implement the code, but used the MATLAB wrapper instead. He also wrote a wrapper on top of the wrapper to make things easier.

- Ray.

]]> By: emy http://www.shawnlankton.com/2007/12/3d-vision-with-stereo-disparity/comment-page-1/#comment-1260 emy Thu, 28 Jan 2010 18:59:54 +0000 http://www.shawnlankton.com/2007/12/3d-vision-with-stereo-disparity/#comment-1260 sorry but i have another question , you say above, First, we segment the reference image using a technique called “Mean Shift Segmentation" , but i linked to mean shift segmentation but i cann't find the matlab code. emy sorry but i have another question , you say above, First, we segment the reference image using a technique called “Mean Shift Segmentation” , but i linked to mean shift segmentation but i cann’t find the matlab code.

emy

]]> By: emy http://www.shawnlankton.com/2007/12/3d-vision-with-stereo-disparity/comment-page-1/#comment-1259 emy Thu, 28 Jan 2010 18:32:51 +0000 http://www.shawnlankton.com/2007/12/3d-vision-with-stereo-disparity/#comment-1259 hi shawn , thank you about your effort, it is nice work. i execute the stereo_nofilter function, i need your help to understand why are you used gradient function in your program ? what are you mean by this line? d = CSAD+weight*CGRAD; i wrote aprogram to compute the disparity map but by another technique it depend on using window 3x3 or 5x5 or 7x7 and calculate the disparity for the center pixel in this window , but you calculate the disparity for all image!!!! emy hi shawn , thank you about your effort, it is nice work.
i execute the stereo_nofilter function, i need your help to understand why are you used gradient function in your program ? what are you mean by this line?
d = CSAD+weight*CGRAD;
i wrote aprogram to compute the disparity map but by another technique it depend on using window 3×3 or 5×5 or 7×7 and calculate the disparity for the center pixel in this window , but you calculate the disparity for all image!!!!

emy

]]> By: Shawn Lankton http://www.shawnlankton.com/2007/12/3d-vision-with-stereo-disparity/comment-page-1/#comment-1176 Shawn Lankton Tue, 24 Nov 2009 13:50:56 +0000 http://www.shawnlankton.com/2007/12/3d-vision-with-stereo-disparity/#comment-1176 @Philip. It is not too complicated. Check out the book, "Multiple View Geometry in Computer Vision" by Richard Hartley, Andrew Zisserman. @Philip. It is not too complicated. Check out the book, “Multiple View Geometry in Computer Vision” by Richard Hartley, Andrew Zisserman.

]]> By: Shawn Lankton http://www.shawnlankton.com/2007/12/3d-vision-with-stereo-disparity/comment-page-1/#comment-1175 Shawn Lankton Tue, 24 Nov 2009 13:49:20 +0000 http://www.shawnlankton.com/2007/12/3d-vision-with-stereo-disparity/#comment-1175 @Philip. This line is kind of a hack. It just centers the disparity image between the two reflectance images. @Philip. This line is kind of a hack. It just centers the disparity image between the two reflectance images.

]]> By: Philip http://www.shawnlankton.com/2007/12/3d-vision-with-stereo-disparity/comment-page-1/#comment-1170 Philip Tue, 17 Nov 2009 17:04:36 +0000 http://www.shawnlankton.com/2007/12/3d-vision-with-stereo-disparity/#comment-1170 Hai Shawn, can u explain more about ur stereo m file, line 59, "pd = shift_image(pixel_dsp,5); ". Why the shift value is 5? Hai Shawn, can u explain more about ur stereo m file, line 59, “pd = shift_image(pixel_dsp,5); “. Why the shift value is 5?

]]> By: Philip http://www.shawnlankton.com/2007/12/3d-vision-with-stereo-disparity/comment-page-1/#comment-1169 Philip Tue, 17 Nov 2009 10:35:46 +0000 http://www.shawnlankton.com/2007/12/3d-vision-with-stereo-disparity/#comment-1169 Hi Shawn, how to converted pixel disparity to actual distance from the camera geometry? Hi Shawn, how to converted pixel disparity to actual distance from the camera geometry?

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