If the height you set in the app is different with the actual camera height, there is 2 possible option that can happen.
1) Each scan points on the floor will not represent the real position.
The points will appear much higher than where they were supposed to appear. For example, instead of having points on the floor, they may appear in the middle of a wall or on a table.
2) Virtual measurement might work incorrectly.
When using virtual measurement in the viewer, the extracted measurement will be wrong.