# parallax difference

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Related to parallax difference: Parallax error

## parallax difference

In the above illustration, the principal points of the photographs can be accepted as the nadir positions. Both the top and base the objects are clearly visible. The absolute stereoscopic parallax is 10.36 mm in this case, i.e., the sum of the distances of the corresponding images from their respective nadirs. Parallax difference in this case is the difference in the absolute stereoscopic parallax at the top and base are the objects being measured i.e., 10.36–10.32 = 0.04.
The difference between the absolute stereoscopic parallax at the top of the object and at the bottom of the image. It is represented customarily by the symbol dp. The absolute stereoscopic parallax on truly vertical photographs, taken at the same height, is the algebraic difference, parallel to the line of flight, of the distances of the two images of a given object at their base from their respective principal points. Used customarily in the determination of the difference between the elevations of two objects.