I am doing a project to measure the roughness parameter of a plastic surface( 35 mm X 35 mm) coated with a matte white spray paint. I am using Nikon 3400D with macro lens (60 mm focal length) and the camera is fixed with a stepper motor that can move over the surface in x and y-direction. No reference objects(scale bar/chess board) were used and the camera is set upside down to take the surface images. Camera positions and movements are known and I imported this known coordinates(CSV files) in Agisoft. Every time when exporting the coordinates from the point cloud, I am getting the result with a large deviation when comparing with the standard microscopic values. I really don't know how to figure out this problem. Can anyone help me out here? Thanks.