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QTVR Panoramas - Implications
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Correcting the Camera for Parallax
Just as care must be exercised when leveling the camera, so too must you correct for parallax in the captured images. Parallax results when the focal point (also called the nodal point) of the camera lens is offset from the camera's point of rotation. This offset causes foreground objects to appear to move relative to more distant objects when the camera is panned from side to side.
Apparent movement of foreground objects caused by parallax
You can check this for yourself by trying out the following:
- Stand where you can see both nearby and distant objects or landmarks.
- Cover one of your eyes with a piece of paper or your hand.
- Pivot your head, noting any apparent motion of foreground objects in relation to more distant objects.
- This motion is called parallax, and it results from the fact that your point of rotation (the middle of your spine) is not the same as the focal point of your eye.
Parallax occurs when a camera is mounted on a typical tripod. All tripods provide a camera mount which rotates the camera on a point near the camera's film plane. However, the nodal point of the lens (where the image comes into a single point of focus) is normally close to the rear optic of the lens.
To correct for parallax, the camera must be mounted so it rotates on the nodal point of the lens. This can be achieved either with a combination of off-the-shelf photographic gear or by using rigs sold by QTVR vendors.
Either way, the essentials are the same; the camera should be mounted so it rotates around the nodal point of the lens on an axis that is perpendicular to the center of the lens, similar to the graphic below.
Camera rig with upper and lower pan/tilt heads
| If all foreground features are relatively distant in the view, then parallax effects are not a problem. |
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