Resolutions

What is spatial resolution

The ability to discern objects on ground. With it, the smallest size of an object that can be picked out from its surrounding objects or features (typically expressed in km, meters, cm etc)

What is the correlation between spatial resolution and image detail

Higher the spatial resolution the more detailed image (able to resolve smaller features)

What is spectral resolution

The number and dimension of specific wavelength interval of the EMR that a sensor is capable of measuring (the width and number of spectral bands).

What are wavebands

The portions (ranges) of the spectrum to which an instrument is sensitive

How do waveband widths vary in spectral bands

A sensor can have multiple wavebands bands of varying widths, within each band no spectral variation can be resolved. The width of each spectral band determines its spectral resolution

What are the three types of spectral resolution

-Panchromatic

-Multispectral

-Hyperspectral

What is panchromatic resolution

Consist of one wide band that encompasses a large spectral range (often the entire visible spectrum)

What is multispectral resolution

Consists of relatively narrower several bands of which two or three bands in the visible range and also have a few near-infrared or middle infrared bands.

What is hyperspectral resolution

Consists of large number of narrower bands spread across the EMR

What is radiometric resolution

The number of unique values that can be recorded by a sensor when measuring reflected or emitted EMR (signal precision)

How is radiometric resolution quantified/expressed

Quantified as a number (e.g., 256, 1024, etc.) and express in bits, the higher the radiometric resolution, the better the data quality

How are bits expressed

 As power of 2, and numbers start from 0

▪ 1 bit = 21 = 2 values (0 and 1)

▪ 2 bit = 22 = 4 values (0,1,2 and 3)

▪ 8 bit = 28 = 256 values (0 to 255)

What is temporal resolution

Shortest period of time that a sensor will revisit/ pass over the same spot on the Earth surface (the sensor revisit frequency)

Why are some areas re-imagined more frequently

Due to some degree of overlap in the imaging swaths of adjacent orbits for most satellites and the increase in this overlap with increasing latitude