pushbroom scanner | multispectral scanner | remote sensing | lecture 2

above video is on multispectral scanner ( pushbroom scanner ) (whiskbroom scanner ).
This is the lecture 7(2) of remote sensing and gis. In this video of pushbroom scanner we first study about the sensor and then type of sensors and after that multispectral scanners and then types of multispectarl scanner and then pushbroom scanner / pushbroom sensor.
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SENSOR --
A sensor is a device that gathers electromagnetic radiations, converts it into a signal.
Based upon the form of the data output, the sensors are classified into photographic (analogue) and non– photographic (digital) sensors.
A photographic sensor (camera) records the images of the objects at an instance of exposure.
On the other hand, a non–photographic sensor obtains the images of the objects in bit-by-bit form. These sensors are known as scanners.

Multispectral Scanners ----
In satellite remote sensing, the Multi Spectral Scanners (MSS) are used as sensors. These sensors are designed to obtain images of the objects while sweeping across the field of view.
A scanner is usually made up of a reception system consisting of a mirror and detectors. A scanning sensor constructs the scene by recording a series of scan lines.
It is because of such reasons that the mode of collection of images by scanners is referred bit–by–bit.
The Multi-Spectral Scanners are divided into the following types:

(i) Whiskbroom Scanner
(ii) Pushbroom Scanner

whiskbroom scanner ----
The whiskbroom scanners are made up of a rotating mirror and a single detector. The mirror is so oriented that when it completes a rotation, the detector sweeps across the field of view between 90 - 120 to obtain images in a large no. of narrow spectral bands ranging from visible to middle infrared regions of the spectrum.

pushbroom scanner ---
Push broom scanners, also sometimes referred to as along track scanners, use a line of detectors arranged perpendicular to the flight direction of the spacecraft. As the spacecraft flies forward, the image is collected one line at a time, with all of the pixels in a line being measured simultaneously (Fig. 2). A push broom scanner receives a stronger signal than a whisk broom scanner because it looks at each pixel area for longer. One drawback of push broom sensors is that the detectors in the "push broom" can have varying sensitivity. If they are not perfectly calibrated, this can result in stripes in the data.

The pushbroom scanners consist of a number of detectors which are equivalent to the number obtained by dividing the swath of the sensor by the size of the spatial resolution

example of pushbroom scanner : the swath of High Resolution Visible Radiometer – 1 (HRVR – 1) of the French remote sensing satellite SPOT is 60 km and the spatial resolution is 20 metres. If we divide 60 km x 1000 metres/20 metres, we get a number of 3000 detectors that are deployed in SPOT HRV – 1 sensor
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you can also watch ---

GIS --- class 1: introduction to gis : https://youtu.be/-5dfbW57EwE
GIS --- class 2 : components of gis : https://youtu.be/rSNm3pJ1e1o

1: remote sensing and gis (playlist) -- https://www.youtube.com/playlist?list=PLp76zJxzEriMstHWJssWiczio7rtIAU6r

REMOTE SENSING LECTURES --
Class 1: remote sensing in hindi - https://youtu.be/1zwg-siuvuc

Class 2: remote sensing process in hindi - https://youtu.be/UokHOfOyrVw

Class 3: history of remote sensing -- https://youtu.be/rxgZO6W4czs

Class 4(i) : remote sensing platforms in hindi -- https://youtu.be/vJEN-zaXp1s

Class 4(ii) : remote sensing sensors - https://youtu.be/YfPCSSFAfdQ

Class 5 : emr in remote sensing - https://youtu.be/hv5FfK99ojQ

Class 6 : application of remote sensing -- https://youtu.be/rd16otLMbVw

Class 7 (part 1) : whiskbroom scanner -- https://youtu.be/7IWZAXsN2rY

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