Digital Photogrammetry & Point Clouds Flashcards
6 cards from real Certified Photogrammetrist practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Digital Photogrammetry & Point Clouds flashcards as text
What is 'voxel-based' point cloud processing?
Answer: Processing point clouds in a 3D grid of volumetric cells (voxels) for efficient spatial analysis
Voxel-based processing divides 3D space into a regular grid of volumetric cells (voxels), enabling efficient spatial indexing, subsampling, and analysis of large point clouds.
In digital photogrammetry, what is 'epipolar geometry' used for?
Answer: Constraining image matching to a 1D search along epipolar lines, reducing computation and false matches
Epipolar geometry constrains the search for corresponding points to a one-dimensional line (epipolar line) in the second image, dramatically reducing computation and eliminating many false matches.
What is the purpose of 'thinning' or 'decimating' a point cloud?
Answer: Reducing point cloud size by removing redundant points while preserving surface representation
Point cloud thinning/decimation reduces the number of points by removing redundant ones while preserving the essential shape and detail of the surface, making processing more manageable.
In photogrammetric software, what does 'tie point extraction' (e.g., SIFT, SURF) accomplish?
Answer: Detecting distinctive image features and matching them across overlapping images for use in bundle adjustment
Algorithms like SIFT and SURF detect distinctive keypoints in images and match them across overlapping photos, creating the tie points used in bundle adjustment.
What is 'photogrammetric restitution' in the context of digital mapping?
Answer: The process of extracting planimetric and topographic features from stereo imagery for map compilation
Photogrammetric restitution is the process of extracting map features—planimetric (roads, buildings) and topographic (contours, elevation)—from oriented stereo imagery for map production.
Which file format is used to exchange dense point clouds with both geometry and per-point color information?
Answer: LAS/LAZ (with RGB fields) or PLY format
LAS/LAZ files support per-point RGB color fields, and PLY format stores geometry with color attributes, both commonly used for colored dense point clouds from photogrammetric processing.
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