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GIS test two, digital images

front 1 Digital images are a recording of __________ received by a sensor.	back 1 photons
front 2 What is the difference between the possible values given by analogue vs digital instruments?	back 2 Analogue: infinite number of possible values Digital: discrete number of possible values (no in between)
front 3 What is a charge-coupled device (CCD)?	back 3 An array of silicon atoms (a grid) whose bonds can be broken by absorbing light (photons) of various wavelengths.
front 4 What is an Instantaneous field of view (IFOV)?	back 4 A sensor's angular cone of visibility

front 5 Define spatial resolution.	back 5 The smallest unit of area the sensor can collect information about
front 6 What are Digital Numbers (DN)? What are they also referred to as?	back 6 The energy measured in a single pixel according to a predetermined scale, Brightness Value (BV)
front 7 DN is measure ___________, not reflection.	back 7 radiance
front 8 A low DN value means ___________ radience.	back 8 little

front 9 What is Radiometric Resolution?	back 9 A sensor’s ability to determine fine differences in energy measurements AKA Sensitivity of a sensor to differences in signal strength
front 10 What is a Bit?	back 10 short for ‘Binary Digit’, Basic unit of information used in computing and digital communications
front 11 What values can a bit have? What is the expression for how many possible combinations of bit values there are?	back 11 only one of two values, most commonly either 0 or 1 2ⁿ (n = number of bits), therefore 2 bits would have 4 (22) values
front 12 The __________ of a radiometric resolution corresponds to the number of bits used for coding numbers in a binary format.	back 12 range

front 13 Most commonly sensors will have _____ bit data but more advanced sensors have _____ bit data	back 13 8, 12
front 14 The bands of colour used to render digital images are (discrete/continuous).	back 14 Discrete
front 15 Why don't digital images have colour? What does this mean for the initial display of digital numbers?	back 15 Colour is used for interpretation, greyscale presentation
front 16 A _____________ sensor measures the visible spectrum as one band. This results in a ___________-and-___________	back 16 Panchromatic, black-and-white

front 17 A ____________ ____________ is an image formed by displaying the DNs of one band as red, a second band as green, and a third as blue.	back 17 colour composite
front 18 How is True colour composite different from a colour composite?	back 18 True colour matches red, green and blue to DN values that are red, green and blue respectively in real life. It is a type of colour composite.
front 19 An image where the distribution of the band differs from a true colour composite is called what?	back 19 A False colour composite
front 20 What is the standard for which bands are represented by RGB in a false colour composite?	back 20 • NIR represented by red • Red represented by green • Green represented by blue

front 21 What is the spectral resolution of an sensor?	back 21 The number and width of bands measured by a sensor
front 22 A multispectral sensor will have ___-10 ___________ bands while a hyperspectral sensor will have hundreds of ___________ bands.	back 22 3, wider, narrow