Remote Sensing and Image Analysis Flashcards

Which type of remote sensing uses its own energy source to illuminate a target and record the reflected signal?

Answer: Active remote sensing

Active remote sensing systems, such as radar and LiDAR, emit their own electromagnetic energy and measure what is reflected back from the surface.

What is the Normalized Difference Vegetation Index (NDVI) primarily used for in remote sensing?

Answer: Assessing vegetation health and density

NDVI is calculated from near-infrared and red band reflectance values to quantify vegetation density and health across a landscape.

In Landsat 8 imagery, which band combination is most commonly used for a standard true-color composite?

Answer: Bands 4-3-2

A true-color composite assigns red, green, and blue wavelength bands (Bands 4, 3, and 2 in Landsat 8) to display colors as the human eye would perceive them.

What does spatial resolution refer to in the context of satellite imagery?

Answer: The smallest distinguishable ground feature size in an image

Spatial resolution defines the smallest ground area that can be distinguished as a separate entity in an image, typically expressed as pixel size on the ground.

Which atmospheric correction method converts raw digital numbers to surface reflectance by removing atmospheric effects using sensor-measured path radiance?

Answer: Dark object subtraction (DOS)

Dark object subtraction assumes that the darkest pixel in each band should have near-zero reflectance and uses it to estimate and remove atmospheric path radiance.

What is the primary advantage of hyperspectral sensors over multispectral sensors?

Answer: Hundreds of narrow contiguous spectral bands enabling detailed material identification

Hyperspectral sensors capture hundreds of narrow, contiguous spectral bands, allowing identification of specific materials and chemicals by their unique spectral signatures.