Texas Surveyor in Training Practice Test 2026 - Free Surveyor Practice Questions and Study Guide

In the relief displacement formula, the variable that represents the radial distance from the principal point is denoted by "r." This formula is used to calculate how the displacement of an object in an image (such as a photograph or a satellite image) occurs due to variations in the object's height above the ground level relative to the camera or sensor.

Understanding the role of "r" is crucial, as it helps in determining how displacement increases with distance from the principal point. The principal point is the point where the optical axis of the camera meets the ground. As the distance (or radial distance) from this point increases, the relief displacement also increases, leading to more significant distortion in the representation of the object.

In essence, "r" is essential for accurately assessing how height variations affect the portrayal of features in aerial or satellite imagery. The other variables in the formula represent different aspects of the measurement process, such as the height of the object or the distance from the sensor, but it is "r" that specifically addresses the radial distance from the principal point, making it key to understanding relief displacement.