Given a spacecraft flying height H, air base length B, and a parallax variation dp, the elevation differential is expressed as___________________?
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Answer: A. h = dp/(B/H)
Explanation
Stereoscopic parallax formulas derive elevation differences by dividing parallax variation by the base-to-height ratio. Flying height and air base length establish the geometric scaling factor required for height calculations from stereo pairs. Rearranging the fundamental photogrammetric equation yields the correct ratio where parallax variation is divided by base-height. Stereoscopic parallax is the apparent displacement of a point on two overlapping aerial photographs taken from different positions. Air base length represents the distance between camera stations during successive aerial photograph exposures. Photogrammetrists use height formulas to construct topographic contour maps from stereo aerial image pairs.
Mapping agencies compute digital elevation models from overlapping aerial photographs using precise parallax measurements. Civil engineers analyze stereo pairs to determine terrain relief for highway and dam construction projects. Accurate flying height records are essential for calculating correct ground elevations from aerial stereo models. Option B incorrectly multiplies parallax variation by the base-to-height ratio instead of dividing by it. Option C inverts the denominator ratio, leading to incorrect dimensional units for elevation calculations. Option D incorrectly places the flying height over base length in the numerator position.
- Subject
- Engineering
- Category
- Civil Engineering
- Topic
- —
- Difficulty
- medium
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