Photogrammetry Quiz

Answers and explanations appear as you take the quiz.

1. What is the primary requirement of the input photos for photogrammetry to work?
   • They must be taken with a flash
   • They must significantly overlap and view the scene from different angles
   • They must all be taken from the exact same position
   • They must be black and white
2. What does Structure-from-Motion (SfM) compute?
   • Only the colors of each pixel
   • The lighting conditions of the scene
   • A video of the camera moving
   • Camera positions/orientations and a sparse set of 3D points simultaneously
3. What does bundle adjustment minimize?
   • Reprojection error across all cameras and 3D points
   • Total file size of the images
   • The number of cameras used
   • Battery usage during capture
4. What is the role of Multi-View Stereo (MVS) after SfM?
   • To delete the original photos
   • To compress the camera poses
   • To densify the sparse points into a dense point cloud or mesh
   • To re-take the photos automatically
5. Why are ground control points (GCPs) often used in surveying-grade photogrammetry?
   • To make the photos look brighter
   • To increase the number of photos needed
   • To remove the need for cameras
   • To anchor the model to real-world scale and coordinates for accuracy
6. Why can a textureless or strongly reflective surface be difficult for feature-based photogrammetry?
   • It guarantees that every camera pose is known exactly
   • It may provide few stable, repeatable visual correspondences across views
   • It makes image overlap unnecessary
   • It automatically supplies surveyed ground coordinates
7. What distinguishes camera intrinsics from camera pose in a photogrammetric reconstruction?
   • Intrinsics are scene-point coordinates and pose is only JPEG quality
   • Both terms mean only the camera's model name
   • Intrinsics describe projection properties such as focal length; pose describes position and orientation
   • Pose supplies the lens's distortion coefficients while intrinsics gives its geographic location
8. In a calibrated central-camera photogrammetry model, what geometric relation underlies triangulation?
   • A scene point, camera center, and its projection lie on a viewing ray
   • All scene points must share the same image pixel
   • Every photograph supplies absolute depth without another constraint
   • The camera center is always identical to the scene point