Which term is used for a positive aerial photograph printed on a glass plate for stereoscopic plotting?

The term "diapositive" refers to a positive aerial photograph that has been processed and printed on glass, suitable for stereoscopic plotting. This process creates a transparently positive image that can be used in various applications, including photogrammetry, where accurate three-dimensional representations of terrain are derived from two-dimensional photographs.

In stereoscopic plotting, the diapositive allows the viewer to perceive depth through a pair of photographs taken from slightly different angles, which is essential for mapping and surveying applications. The clarity and quality of the diapositive enable precise measurements and analysis, making it a valuable tool for surveyors.

As for the other choices, a collimator is an optical device used to align the optical axes of instruments, often for sighting purposes, rather than for creating photographs. An aerial camera is the actual device used to capture aerial photographs but does not refer specifically to the processed positive image. An intervalometer is a device that controls the duration of intervals between exposures but has no relevance to the aerial photographs themselves.