CST Level 1 Land Surveyor Certification Practice

What is the primary purpose of setting ground control in photogrammetry?

1. To enhance data storage capacity

2. To improve accuracy of measurements

3. To reduce the need for instruments

4. To eliminate the use of GPS

The correct answer is: To improve accuracy of measurements

The primary purpose of setting ground control in photogrammetry relates directly to improving the accuracy of measurements. Ground control points are reference points on the ground with known coordinates that are used to ensure that the images collected during a photogrammetric survey can be accurately georeferenced. These points enable surveyors to align the images correctly and to scale and orient them in relation to real-world coordinates, thereby enhancing the precision of the derived measurements. Accurate ground control is essential for transforming two-dimensional images into a reliable three-dimensional representation of the terrain or objects being surveyed. Without these control points, the resulting data may suffer from misalignment and positional inaccuracies, which would significantly diminish the quality and reliability of the photogrammetric outputs. Considering the context of the other options, enhancing data storage capacity does not directly relate to the function of ground control, nor do ground control points reduce the need for instruments, as the verification and adjustment of measurements still require tools for proper implementation. Similarly, ground control does not eliminate the use of GPS; rather, it often works in conjunction with GPS technology to improve overall survey accuracy.