LECTURE3 MULTISPECTRAL SCANNERS Department of City Regional Planning

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LECTURE#3 MULTISPECTRAL SCANNERS Department of City & Regional Planning Lahore College for Women University,

LECTURE#3 MULTISPECTRAL SCANNERS Department of City & Regional Planning Lahore College for Women University, Lahore. Notes By: Saba Islam

SCANNING The process to convert hard copy aerial photos into digital photos For scientific

SCANNING The process to convert hard copy aerial photos into digital photos For scientific applications high metric scanners are required Quality of the scanning depends upon quality of scanner and settings of the scanner Office scanner can provide up to 600 dpi where as professional scanner can go up to 3600 dpi

MULTISPECTRAL SCANNERS (MSS) The measurements are made for different ranges of EM Spectrum •

MULTISPECTRAL SCANNERS (MSS) The measurements are made for different ranges of EM Spectrum • Used in Remote Sensing since 1972, after first Landsat satellite was launched • Main applications are mapping of Land cover Vegetation Surface mineralogy Surface water

SPATIAL CHARACTERISTICS Scale Focal length and flying height define the photo scale Scale is

SPATIAL CHARACTERISTICS Scale Focal length and flying height define the photo scale Scale is determined by s=H/F Spatial Resolution Ability to record small adjacent records in an image

TYPE OF MSS – Whiskbroom Scanner – Pushbroom Scanner

TYPE OF MSS – Whiskbroom Scanner – Pushbroom Scanner

WHISKBROOM SCANNER Also called across track scanner Use Solid state detectors to measure the

WHISKBROOM SCANNER Also called across track scanner Use Solid state detectors to measure the energy transferred by the optical system to the sensor Prism and gratings are used to split the incoming radiation for their own detector. Detectors transform the electro magnetic radiation (photons) into electrons. Range between maximum or minimum level that a detector can handle is called dynamic range.

WHISKBROOM SCANNER

WHISKBROOM SCANNER

GEOMETRIC CHARACTERISTICS – Viewing angle of the system is also referred to as Instantaneous

GEOMETRIC CHARACTERISTICS – Viewing angle of the system is also referred to as Instantaneous Field of View (IFOV). – The IFOV determines the spatial resolution of a scanner – The Field Of View (FOV) describes the total angle that is scanned.

PUSHBROOM SCANNER Spectral Characteristics One detector array for one Band Maximum capacity is 2.

PUSHBROOM SCANNER Spectral Characteristics One detector array for one Band Maximum capacity is 2. 5μm For longer wavelengths other detectors are required It is difficult to produce an array in which all the elements have similar sensitivity.

PUSHBROOM SCANNER

PUSHBROOM SCANNER

GEOMETRIC CHARACTERISTICS Geometry similar to aerial photograph Scale remain same over one line in

GEOMETRIC CHARACTERISTICS Geometry similar to aerial photograph Scale remain same over one line in case of flat terrain and limited field of view Off track viewing is possible Produce Stereo images Detect cloud cover areas Scale needs to correct in case of off track viewing Data store in strip by strip pattern in every millisecond to convert it in DN values.