If your question is: how to measure the size in two dimensions, and how to keep the original size unchanged after enlargement?

The answer is: 1, first of all, we must choose the second element with good quality and high precision; 2. The second dimension is measured by the enlarged image, so the deformation of the lens and camera will affect the image measurement result; 3. Whether the two-dimensional measurement software is guaranteed, some bad software will have great differences when calculating circles or straight lines, that is, the problem of algorithm; 4. Measure the quality of personnel. The position of image measurement point is very important, and the results of different positions may be very different. Strengthen the training of surveyors.