Measuring From Long Range Oblique Photography (LOROP) (1987)

ABSTRACT Long Range Oblique Photography (LOROP) has been investigated briefly as a means of collecting quantitative data about very distant scenes. Two measuring aspects are discussed: first, producing dimensional data about the sizes and heights of man-made objects, and, secondly, measuring the geographic location of an object. This latter task is rather new for the photo intelligence specialist, who in the past generally did not have available these photogrammetric capabilities.We show in this contribution that at stand-off distances of 130 kms (80 miles), a position can be routinely measured with an accuracy better than ±10 m, in less than 15 minutes.1. IntroductionThe end goal of all photo reconnaissance collection equipment (including aircraft and crew, cameras, electronics, photo lab, etc.) is to deliver a quality image to the photo intelligence specialist. Once this is done, his task is to study the imagery, extract the intelligence information, and communicate it effectively into the system. The information which he produces can usually be categorized under one of the following headings:inventory of the military equipment at a site; activity status of a known target; - description of a newly discovered facility; dimensioning ground facilities or equipment; geographic location of a new target.The first three items in the list have been quite standard for most military Photo Interpreters (or Image Analysts) ever since the blossoming of photo intelligence capabilities during World War II. These capabilities are taken for granted, whether from vertical photography from oblique or other images. The fourth item in the list, dimensioning, has been very much less practiced during interpretation work from oblique images. The techniques are taught in most rigorous Photo Interpretaion (PI) courses. They are also available in PI reference books such as those included in the references. However, the techniques are slow and awkward, and are very susceptible to arithmetical blunders. Thus, for the most part, dimensioning from oblique photography has been practiced for training purposes, but only rarely in reconnaissance operation where time pressures exist.The last task in the list above, determining geographic location of a target, has not been practiced at all by photo interpreters, as a measuring process from an image. The best he could generally do was to eyeball the target's approximate location onto a reference map, and then extract the geographic coordinates from the map, for use in the photo intelligence reporting cycle.In the past, the image analyst did not produce much dimensional and positional intelligence from oblique photography, not because it is not needed, but because he could not. As a result of the mensuration light table and the microcomputer, all of this is changing. It is our contention that, as a result of these new capabilities (implemented in smooth and efficient hardware and software), the PI will be expected to routinely produce much more numerical data. The quality of that numerical data should begin to come close to matching that which a photogrammetrist could produce from the same photography but specialized photogrammetric precision equipment.