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This information paper from the All-domain Anomaly Resolution Office (AARO), dated May 2024, explains how forced perspective and parallax can lead observers to misjudge the size, speed and direction of unidentified anomalous phenomena. Using examples such as the Leaning Tower of Pisa, a featureless sphere and an airborne sensor passing over a river, it shows how stationary objects can seem to move. It concludes that single-observer reports still matter and that observers should estimate range, size and speed.
All-domain Anomaly Resolution Office (AARO) 2 person is between five and six feet tall. In this example, forced perspective distorts the distance between the tower and the person, causing both the person to appear larger and the tower to appear smaller than their true sizes. The example above demonstrates the effects of forced perspective. Recognizing the optical illusion in this case is easy because the actual sizes of both objects in the image are known. However, judging the sizes of unknown objects in the sky is harder. Observers will often compare unknown objects to clouds, trees, buildings, or other non-standard references to make estimates. Observers can, therefore, inaccurately perceive the distance between an object and a reference, leading to an inaccurate estimate of the object’s actual size. Making an error while estimating an object’s size or distance is even more likely if, unlike the Tower of Pisa, the object has no discernable features (e.g., windows, propellers, wings). Consider a case in which there are no references against which to compare an unknown object. In such a case, an observer must estimate its distance without any clues. Accurately estimating an object’s size and distance without a known reference is difficult. Forced perspective can cause large, faraway objects to appear smaller and closer than their actual size and position - or vice versa. The image in Figure 2 demonstrates this effect. A 10’ sphere with no features (e.g., windows, lines, surface details) positioned at an unknown distance from an observer may appear smaller or larger than its actual size, depending on the observer’s reference point and assumptions. Figure 2: The 10’ sphere on the far right is an unknown distance from the observer. If the observer estimates the range to be shorter, they will estimate the size to be smaller.
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Report, from the aaro collection. The PDF is mirrored here; the original link is above. 4 pages are in the text index: search them above, or from the library's search.