What is the main benefit of using stereo photographs in surveying?

The primary benefit of using stereo photographs in surveying lies in their ability to determine elevations. Stereo photographs are taken from two slightly different angles, creating a three-dimensional effect. When viewed together, these images allow surveyors to perceive depth and elevation variations in the terrain, which is crucial for accurate mapping and analysis. This capability is particularly valuable in topographical surveys, where understanding the contour of the land is essential for a variety of applications, including construction, land development, and environmental assessments.

While color images can provide valuable information and enhance visual comprehension, they do not directly contribute to the measurement of elevation or the complex interpretation needed in surveying tasks. Ease of interpretation is subjective and can depend on the viewer's experience with the medium. Lastly, although cost may be a consideration in the choice of surveying methods, it does not inherently affect the primary objective and utility of stereo photographs in determining elevation. Therefore, the ability to ascertain elevations sets stereo photographs apart as a significant tool in the surveying process.