UNDISTORT STEREO Images before RECTIFICATION ?

This is a query reg. Stereo Rectification using Matlab inbuilt functions

Does one need to :

UNDISTORT the STEREO Images before RECTIFICATION ?

My pair of views are near-perfect, but has large disparity.

Using stereo-Calibration, I get the distortion parameters as (given below for only one of the cameras):

RadialDistortion:

[-0.163 0.0958]

TangentialDistortion:

~ [ 0, 0];

Skew: -0.600.

The 3D back-projected results appear OK, but I am looking for high accuracy. Hence the query.

Any useful advise will be beneficial (thanx in advance, for that)

Answer 1

[Sukhendu]

Thanx a lot.

Your assumptions of functions (stereoCameraCalibrator, followed by rectifyStereoImage) being used are correct.

The disparity is so high that I cannot use disparitySGM or disparityBM functions.

Wrote my own stuff, using ORB/SIFT based correspondences.

I am truely not interested in full scene 3D reconstruction from stereo now, rather estimating 3D Coordinates of few landmark points in the images, with extremely high accuracy.

Answer 2

[Abhinav Aravindan]

Hi @Sukhendu

I assume you are using the “rectifyStereoImages” function for Stereo Image Rectification. In this case, it is not required to undistort your image in prior as the function automatically handles both undistortion and rectification using the stereo calibration parameters you have obtained.

https://www.mathworks.com/help/vision/ref/rectifystereoimages.html#:~:text=rectifyStereoImages(I1%2CI2%2CstereoParams)%20undistorts%20and%20rectifies%20versions%20of%20I1%20and%20I2%20input%20images%20using%20the%20stereo%20parameters%20of%20a%20stereo%20camera%20system%20stored%20in%20the%20stereoParams%20object

To improve your 3D screen reconstruction results, you may try out the following suggestions present in the below link:

https://www.mathworks.com/matlabcentral/answers/153348

I hope this answers your query!