Pratical Work In Geography Chapter 7 Introduction To Remote Sensing

1. Photographic 2. Non-photographic.

1. Vertical 2. Horizontal 3. Oblique

4. Convergent 5. Trimetrogen.

1. Size 2. shape 3. shadow 4. tone 5. colour 6. texture 7. pattern 8. associated relationship.

1. It gives a synoptic view of region rather than a district or block.

2. It provides a reliable and real or near real time base line information.

3. It is relatively fast and economical as compared to ground survey.

4. It provides analogue and digital data for visual and digital interpretation respectively.

5. It provides repetitive coverage of the some area which is useful for change monitoring.

6. It is unaffected by bad weather or difficult ground conditions.

Satellite Images : Satellite imagery contrary uses a different mechanism of generating ground images. A ground sense imaged by a sensor board. The features on the earth’s surface are captured in these imageries by detecting characteristics electromagnetic radiation that is reflectance any object of different wavelengths follows a pattern which is characteristics of that object.

Cultural features : These are easily recognisable features in an aerial photograph. Railway lines appear as thin and dark. Certain associated features like stations and sidings make their identification easier. Roads are noticiable through lighter tone. Bridges are recognised as they span water bodies. Urban features like residential buildings, offices etc. can be easily recognised.

Physical features : Tropical rainforests have a near continuous canopy with few clearings. They can be easily identified as the trees are tall to 75-80 m. They appear as unbroken sheet of dark tone. Grasslands are marked by groves. Grass appears in light grey tones in darker tones.

1. Remote sensing satellite data acquisition, storage processing and dissemination.

2. Application of remote sensing for mapping monitoring and management of natural resources.

3. Operational flight facilities to provide several remote sensing services.

4. Training to users.

5. Research and technology development.

Pushbroom Scanners: 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. For example, 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. In push broom scanner, all detectors are linearly arrayed and each detector collects the energy reflected by the ground cell (pixel) dimensions of 20 metres at a nadir's view.

Pushbroom Scanners

Whiskbroom Scanner and it operation: The whiskbroom scanner is 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° and 120° to obtain images in a large number of narrow spectral bands ranging from visible to middle infrared regions of the spectrum. The total extent of the oscillating sensor is known as the Total Field of View (TFOV) of the scanner. While scanning the entire field, the sensor's optical head is always placed at a particular dimension called the Instantaneous Field of View (IFOV) figure depicts the scanning mechanism of whiskbroom scanner. The push broom scanner consists a large number of ditietois which are equivalent to the number obtained by dividing the swath of the season. Whiskbroom scanner is made up of relating mirror and single dictator.

Whiskbroom Scanners

C.

A.

B.