Hello Subetha , maybe just average in 3x3/5x5? I assume there are enough depth points so eg. nose landmark will be at least a few pixels away from cheek landmark, so you could do some averaging. You could also try setting depth confidence to 255, which will result in much less invalid depth pixels (but lower accuracy):
stereoDepthNode.initialConfig.setConfidenceThreshold(255)
Thanks, Erik