Related Concepts and Terminology
In the image on the left, we are again looking down the eye coordinate system y axis, and we have removed some of the axis labeling for clarity. Our left and right eyes see two different projections of the teapot as we noted on the previous page. Let us focus attention on a single point and introduce some relevant terms for stereo viewing.
In the two examples in the table below, we see a single model point being projected for each of the left and right eyes. We then see on the projection plane the respective left and right eye projections of the single model point. We begin with some definitions.
- Definition: Two projected points (one for the left eye and one for the right eye) are homologous if they are projected from a common model point.
- Definition: Horizontal parallax describes the horizontal
separation between two homologous points.
- Positive horizontal parallax means that the projection of the point for the right eye appears to the right of that for the left eye. (See the image in column 1 of the table.)
- Negative horizontal parallax means that the projection of the point for the right eye appears to the left of that for the left eye. This will be the case when the model point lies between the projection plane and the left and right eyes as in the image of column 2 of the table.
- Definition: Vertical parallax describes the vertical separation between two homologous points.
| Homologous Points Exhibiting Positive Horizontal Parallax |
Homologous Points Exhibiting Negative Horizontal Parallax |
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