Rotation and Translation from stereo calibration parameters

Hey guys i have two points clouds, with its stereo calibration files (stereoParams_1 and stereoParams_2) . I'd like to do the 3-D Point Cloud Registration. I understood in example(https://www.mathworks.com/help/vision/examples/3-d-point-cloud-registration-and-stitching.html), that an initial estimation is performed using pcregrigid, to get Rotation and Translation. But instead of use this initial estimation. How can i do the registration using my own stereo parameters (stereoParams_2.RotationOfCamera2 and stereoParams_2.TranslationOfCamera2) ?

Any idea is welcome, thanks in advance. Ana