Remote Sensing and Image Analysis Flashcards
6 cards from real GISP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Remote Sensing and Image Analysis flashcards as text
Which classification approach assigns each pixel to a land cover class based purely on spectral statistics without using any training samples?
Answer: Unsupervised classification
Unsupervised classification algorithms like ISODATA and K-means group pixels into spectral clusters automatically without analyst-provided training data.
What does the term 'geometric correction' in image processing address?
Answer: Correcting distortions caused by sensor tilt, Earth curvature, and terrain relief
Geometric correction involves transforming an image to match a map projection by correcting for sensor geometry, platform motion, Earth rotation, and topographic displacement.
LiDAR point clouds classified as 'ground returns' are primarily used to generate which type of surface model?
Answer: Digital Terrain Model (DTM)
Ground-classified LiDAR returns represent bare-earth elevation and are interpolated to create a Digital Terrain Model that excludes vegetation and structures.
In image classification accuracy assessment, what does the producer's accuracy measure?
Answer: The probability that a reference site is correctly classified on the map
Producer's accuracy (recall) measures how well reference sites of a given class are identified correctly on the classified map, indicating errors of omission.
What is the purpose of pan-sharpening in remote sensing image processing?
Answer: Merging high-resolution panchromatic data with lower-resolution multispectral data
Pan-sharpening fuses a high spatial resolution panchromatic band with coarser multispectral bands to produce a color image at the higher spatial resolution.
Which radar backscatter characteristic makes SAR (Synthetic Aperture Radar) particularly useful for flood mapping?
Answer: Very low or specular backscatter from smooth water surfaces
Open water acts as a specular reflector in SAR imagery, directing microwave energy away from the sensor and resulting in very dark (low backscatter) pixels that are easily distinguished from land.