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Could I choose ROI for stereo initialization?

Open CaesarTheFox opened this issue 6 years ago • 3 comments

My problem is a little like #120. Because part of the picture is not useful and some random pattern may cause large error such as glare. When I do some tests about cross-correlation. I found the cropped pictures have much better result if only considering cross-correlation. The Match in Paraview shows the cross-correlation result. But the problem is that when I crop the picture, it change the coordinate of each pixels and though I get good cross correlation, the model coordinate is wrong.

Cropped picture fm_projective_trans_0

Original picture fm_projective_trans_0 (There is a glare causing incorrect projection and it ruins the result.)

These are fm_projective_trans_0.png. I guess this is to calculate the 8 parameters thing we discussed last time. And right_projected_to_left_color.tif is the result of right plane projected to left plane with those 8 parameters.

So how can I draw ROI for this initilazition step? Is this possible? Or is it possible to use exhaustive search for cross-correlation? Because I struggle with cross correlation now.

CaesarTheFox avatar Jun 25 '19 16:06 CaesarTheFox

In my understanding of cross-correlation prcedure. The initialization is really important in cross-correlation because if the initial guess is too far away from real value, the Newton-Raphson method will never jump there (jump_tolerance is only to avoid nonsense result instead of jump to find true value).

Am I correct? So if I want to improve cross-correlation, it is necessary to get a better initial guess. How close should the initial guess be away from real value?

CaesarTheFox avatar Jun 25 '19 17:06 CaesarTheFox

You are correct about the initial guess, which is sometimes hard in stereo correlation. If you want a good cross-correlation, you need a good initial guess. The initial guess can be roughly 3-5pixels off and will often still converge. Having a better cross-correlation initialization method in DICe is something that is needed. For example if you have a non-planar surface, the cross-correlation will likely fail.

On Jun 25, 2019, at 11:48 AM, CaesarTheFox <[email protected]mailto:[email protected]> wrote:

In my understanding of cross-correlation prcedure. The initialization is really important in cross-correlation because if the initial guess is too far away from real value, the Newton-Raphson method will never jump there (jump_tolerance is only to avoid nonsense result instead of jump to find true value).

Am I correct? So if I want to improve cross-correlation, it is necessary to get a better initial guess. How close should the initial guess be away from real value?

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dicengine avatar Jun 26 '19 19:06 dicengine

So could I choose ROI for stereo initialization?It influences the initialization significantly. Now I need to mask the part I dont want in Photoshop before processing. If we can have such a feature it would be more convenient I guess.

CaesarTheFox avatar Jun 27 '19 15:06 CaesarTheFox