Your scanner set up and amount of natural light in the room can interfere with the quality of your scans.
Step 1: Make sure that the backdrop for your scan (the wall behind your scan subject on the turntable) is as flat as possible, without reflective surfaces in view. If your tower is facing a corner, or a heavily slanted wall, this will disrupt the scan and cause irregularities.
Step 2: Make sure you have enough space between the back wall, side walls, and the turntable. If the turntable looks black in the scanning view, you may need to increase the distance between the turntable and the walls.
Step 3: Be sure to have as little natural light in the room as possible, as this also can effect the scan negatively.
Step 4: When in scan mode, make sure your turntable is within the circle shown on the screen. This is the optimal space for your turntable to yield the best results.
Step 5: Make sure that the person being scanned is in the appropriate stance. Their arms should be straight out, six to eight inches from their body, hands clenched, palms facing the ground, and elbows facing backwards.