I am trying to estimate the magnification factor of a camera for research purposes and I am running into a few issues. It would be great if someone could help me understand what's going on here. I have tried various questions in this forum on the same topic. But somehow could not find the answers to the specific questions that I am interested in.
- I have an object of known dimension, say 5cm.
- I captured the image of the object in various positions.
- I then compute how many pixels it corresponds to in the image (say 10 pixels).
- I estimate the magnification factor as 5/10 (what 1 pixel corresponds to) 0.5.
The issue is that when I try to image the object in various positions, it corresponds to different number of pixels (varies from 9 to 11). This gives me a different MF in different positions. I assume this is due to perspective.
Am I right in assuming this is due to perspective? Ideally the MF must be constant wherever I place the object in the scene.
Is there an alternative to the method described above?