Stereo/Depth Map WLS filter

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So i am currently polishing my generated depth map, and i can't find any documents about the effect of lambda and sigma for WLS filter and i'm curious what is its effect on the map. Lastly, if i want to make my depth map more polished where would i configure it? in Stereo Calibration or WLS Filter?

As you can see from my generated depth map, the edges are not clear & light colored materials also appear as white (I'm using filter called cv2.COLORMAP_OCEAN where white is near; and dark/less white is far...)