Added New Sample: Stereo Camera Calibration in Real Time

[upperwal]

Captures images in real time by detecting chessboard corners and calibrate the stereo camera after that.

Keyboard Shortcuts:

Initial Mode: Detecting (Chessboard Corners) 'c': Capturing (Start capturing the stereo images) 'p' Calibrate (Once all the images are captured, calibration can start by pressing 'p')

[StevenPuttemans]

:+1: nice tutorial! However afaik you will not be allowed to use any other license than the official OpenCV license.

[upperwal]

Thanks Steven. I was going through opencv coding style guide and found this 'Every source file, except for the samples, starts with BSD-compatible license, which template can be found here.'. So do I use the official BSD licence in the samples as well or not?

Link: http://code.opencv.org/projects/opencv/wiki/Coding_Style_Guide

[StevenPuttemans]

Actually I think that in the near future all files and all samples should point to a single license which can be found here (http://opencv.org/license.html). Not sure on how this is going to be done.

[upperwal]

OK. Got that. Will replace the licence and commit the changes and is it allowed to give a brief description of the sample code and mention the name of the author?

[StevenPuttemans]

Ofcourse that is ! both is encouraged btw !

[upperwal]

Thanks Steven. I updated the sample code with new license.

[upperwal]

Hey! How this PR will be merged in the master branch?

[StevenPuttemans]

Well you need to wait untill the assignee has completely reviewed it and approved, then it will be merged automatically. Keep in mind that all this people do this in their spare time, so it could take a while.

[upperwal]

Ok! Got that! On 11-Oct-2014 6:23 pm, "Steven Puttemans" notifications@github.com wrote:

Well you need to wait untill the assignee has completely reviewed it and approved, then it will be merged automatically. Keep in mind that all this people do this in their spare time, so it could take a while.

— Reply to this email directly or view it on GitHub https://github.com/Itseez/opencv/pull/3306#issuecomment-58748526.

[upperwal]

@vpisarev Merge Please...

[StevenPuttemans]

I guess first thing to do is to merge your commit history. Just do a

 git rebase -i HEAD~9

First replace all entries except the first to squash Then replace to a general commit message And offcourse push back to here your rebased repo

If not, this will never get mergd since it clutters the commit history.

[upperwal]

Thanks Steven :). Merged all my commits. I can understand that my commits could have created a mess.

Cheers

[StevenPuttemans]

:+1:

but it seems you introduced another file .gitignore Can you remove it from your commit. It should not be updated.

[upperwal]

yup... Repo Updated with only one file. Thanks @StevenPuttemans

[upperwal]

@vpisarev Kindly review and approve the code.

[StevenPuttemans]

There was some waiting time due to the release of the 3.0 beta. I guess one of the following days they will have time to check your sample out.

[upperwal]

Thanks @StevenPuttemans. Hoping to get the code reviewed in the coming days.

[upperwal]

@vpisarev should I open a request to push this sample in some other version of opencv and not the master branch?

[upperwal]

hey @vpisarev any update??

[upperwal]

@vpisarev hey! Any update? I have been eagerly waiting for this pr to get merged.

[StevenPuttemans]

@upperwal it seemed that @vpisarev was on holidays until 1 or 2 days ago. He has been back and is graduatly merging pull requests. Just wait a little bit more! I am sure it will get merged since it is a nice addition.

[StevenPuttemans]

Also, please merge both commits, else this will not get accepted!

[upperwal]

Thanks for replying @StevenPuttemans :) and I will definitely merge both the commits asap. :D

[vpisarev]

Hello @upperwal, terribly sorry for long response. I would prefer if this sample will be combined with the offline stereo_calib. We are trying to cleanup OpenCV samples, remove duplicates or close variations, so it would be nice if we have a single calibration sample. This may be difficult, then I'd prefer that at least monocular camera calibration and stereo calibration are 2 samples, not 3 or more.

[upperwal]

Hey @vpisarev, thanks for replying and don't be sorry, I know you guys are very busy. OpenCV samples contain 3 type of calibration files 3calibration.cpp, calibration.cpp and stereo_calib.cpp. Are you suggesting to merge all these samples into one? As my sample is an extension to stereo_calib.cpp (which calibrate using pre saved stereo images, where as my code works on the live video feed) Will it be fine to merge these two samples and let the user decide which method to use?

[vpisarev]

@upperwal, yes, I meant merging your sample and stereo_calib.cpp. 3calibration.cpp can probably be removed and we plan to extend calibration.cpp. So, there is no need to merge everything together, just retaining a single stereo calibration sample would be good enough solution for now.

[upperwal]

@vpisarev :+1: got that. Will try to merge my sample with stereo_calib.cpp and then I will get back to you. Thanks :)

[upperwal]

@vpisarev @StevenPuttemans What from the following is advisable, to load stereo images in the program:

1. Maintain a images name file (such as images.yml) from which name of an image is read and that string is used in imread().
2. Ask the user to give a folder, image prefix (Ex: "imageleft", "imageright"), image post fix (Ex: "jpg") and no of images and iterate using image prefix+i+image post fix to read the images. Given image are image_left_1.jpg, image_right_1.jpg etc.

I am sorry if this is a lame question, but I came across the first method in almost all samples and according to me the second one is more efficient to do. (user does not need to create a file for the name of the images). Please correct me, if I am wrong. Thanks

[StevenPuttemans]

@upperwal it kind of depends I guess. Since you are building the sample, you can choose the method you like. The reason why people use a name file with locations, is because reading files is universal in different OS. Reading from a folder gives different sequences since ordering is different on several OS.

But hey, you choose what fits you the best!

[upperwal]

Thanks @StevenPuttemans :+1: I used the second method for the time being. To have a single sample for stereo calibration I have merged stereo_calib with my sample. The sample can now work on already saved stereo images or click the images on the go.

[StevenPuttemans]

Great :+1:

[StevenPuttemans]

Could you also use your PR to delete the double samples?

[upperwal]

@StevenPuttemans As stereo_calib is updated, there are two calibration samples left. 1. "3calibration.cpp" and 2. "calibration.cpp". So "3calibration.cpp" should be deleted as suggested by @vpisarev as "calibration.cpp" is used for single camera calibration. Correct?

[upperwal]

@vpisarev hi. Can you please review the code?

[StevenPuttemans]

@upperwal I know it is taking some time, but please be patient, I have the idea that some of the devs are on holidays or taking a break :)

[upperwal]

:+1: @StevenPuttemans

[upperwal]

Thanks @StevenPuttemans. You are a great support :+1: :)

[askerpro]

got an error with imread cv::imwrite could not find a writer for the specified extension //std::ostringstream leftString, rightString; //leftString << dir << "/" << prefixLeft << pairIndex << postfix; //rightString << dir << "/" << prefixRight << pairIndex << postfix; std::string leftString = dir + "/" + prefixLeft + to_string(pairIndex) + "." + postfix; std::string rightString = dir + "/" + prefixRight + to_string(pairIndex) + "." + postfix; imwrite(leftString, leftImage); imwrite(rightString, rightImage); works with this

[upperwal]

@askerpro :+1: will fix it ASAP. Thanks :)

[StevenPuttemans]

@upperwal I do not think you should close it down. Just update this branch?

[upperwal]

Hey @StevenPuttemans This PR already have 9 commits, I was thinking of creating a new PR after resolving the merge conflict and incorporating the above suggestion. Will that be fine?

[StevenPuttemans]

@upperwal there is a very nice tool in git called git rebase -i HEAD~9 (change number accordingly) which allows you to concatenate commits and make it a clean PR again. No needc in making a new branch for the fixes!

[upperwal]

@StevenPuttemans Very well then. Let me try it and reopen this PR. Thanks Steven. :)

[upperwal]

Sorry @StevenPuttemans I tried using rebase but it was all messed up and then I did a force push to my repo. I think, now I need to create a new PR for this.

[StevenPuttemans]

Ok no problem at least you tried :D

[upperwal]

:) Thanks @StevenPuttemans