Taking calibration photographs can sometimes involve compromises. For example, you might not have a large enough room, or your camera might not achieve perfect edge-to-edge focus in your setup. The following list shows, in order of priority, considerations for calibration photography. The most important considerations are at the top of the list. If you have to make some compromises, start breaking the rules at the bottom of the list first.
• [For Single Sheet Calibrations only], all four Control Points must appear on all calibration photographs.
• The target sheets should be flat with no sharp bumps or creases. In the case of a paper grid some small creases between the dots is usually OK.
• The target pattern should fill as much of the camera view finder as possible.
• The target pattern should be clean. No shadows or strong marks should appear in the area of the calibration pattern.
• The camera positions should be close to 45 degrees from the horizontal and vertical as needed.
• The photographs should have good focus across the pattern (a small amount of blur due to insufficient depth of field is acceptable).
• All photographs should be taken with the same focus setting (with image stabilization, auto rotation, and sharpening disabled if possible).
• The photographs should have good contrast and not be washed out. There should be a distinct edge between the black and white areas of the pattern.
• The camera should be focused at the distance that will be used for most measurement projects.