Platforms with Sensor on board. Illumination. (Geostationary Satellite) GMS LANDSAT, MOS, SPOT SPACE SHUTTLE HIGH ALTITUDE JETPLANE

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1 Platforms with Sensor on board Illumination GMS (Geostationary Satellite) LANDSAT, MOS, SPOT SPACE SHUTTLE atmosphere HIGH ALTITUDE JETPLANE emission reflection LOW&MIDDLE ALTITUDE AIRPLANE GROUND TRUTH object

2 Contents - Introduction to RS Principles of Remote Sensing electromagnetic radiation atmospheric interaction surface reflection Remote Sensing systems Platforms Sensors Resolution: spatial, spectral, temporal Applications of Remote Sensing

3 Definition of Remote Sensing Remote Sensing is a method to acquire information about material objects, areas, or phenomenon through the analysis of data acquired by a device from measurements made at a distance, without coming into physical contact with the objects, areas, or phenomena under investigation.

4 Why Remote Sensing?

5 Why Remote Sensing?

6 Why Remote Sensing? To recognize macro-patterns which may not be visible from ground To gain an OVERVIEW of an area To gather information on large areas in short time To gather information cost-effectively To gather information on inaccessible places To replace conventional sources of information (topo sheets, census data etc.)

7 What is Remote Sensing? We acquire much information about our surrounding through the senses of sight and hearing which do not require close contact between the sensing organs and the external objects. In another word, we are performing Remote Sensing all the time. Generally, Remote sensing refers to the activities of recording/ observing/ perceiving (sensing) objects or events at far away (remote) places. Earth from Space

8 How does Remote Sensing Work? Electro-magnetic radiation which is reflected or emitted from an object is the usual source of remote sensing data. A device to detect the electro-magnetic radiation reflected or emitted from an object is called a "remote sensor" or "sensor". Cameras or scanners are examples of remote sensors. A vehicle to carry the sensor is called a "platform". Aircraft or satellites are used as platforms. The characteristics of an object can be determined, using reflected or emitted electromagnetic radiation, from the object. Each object has a unique and different characteristics of reflection or emission if the type of object or the environmental condition is different..

9 Principles of RS: EMR The definition of RS implies the use of medium which carries the information from the object to the sensor Usually, electro-magnetic radiation (EMR) is being used as medium In passive RS, the radiation emitted by some other source is being used In active RS, the radiation is being emitted by the system itself

10 Electro-Magnetic Radiation (EMR) / 2 electric field magnetic field travelling direction λ (wave length)

11 The Electro-Magnetic Spectrum 0.3 (cm) Microwave bands W V O Ka K Ku X C S L P Wavelength: Microwaves 0.1nm 10nm 1µm 100µm 10mm 1m 100m 10km γ -ray X-ray UV Vis. Infrared EHF SHF UHF VHF MF LF VLF Radio waves Ultra Violet v I o l e t Visible Light b l u e g r e e n y e l l o w o r a n g e r e d Near Infra-red Short Wave Infra-red Intermediate Infra-red Thermal Infra-red wavelength (µm)

12 Characteristics of spectral regions Region Wavelength Remarks Gamma Ray <0.03 nm Incoming radiation is completely absorbed by the upper atmosphere and is not available for remote sensing. X-ray 0.03 to 3.0 nm Completely absorbed by the atmosphere. Not employed in remote sensing. Ultraviolet 0.03 to 0.4 µm In-coming wavelengths less than 0.3µm are completely absorbed by ozone in the upper atmosphere. Photographic UV band 0.3 to 0.4 µm Transmitted through the atmosphere. Detectable with film and photodetectors, but atmospheric scattering is severe. Visible 0.4 to 0.7 µm Imaged with film and photo-detectors. Includes the reflected energy peak of earth at 0.5µm. Infrared 0.7 to 100 µm Interaction with matter varies with wavelength. Atmospheric Reflected IR band Thermal IR band transmission windows are separated by absorption bands. 0.7 to 3.0 µm Reflected solar radiation that contains no information about thermal properties of materials. The band from 0.7 to 0.9µm is detectable with film and is called the photographic IR band. 3 to 5 µm 8 to 14µm Principal atmospheric windows in the thermal region. Images at these wavelengths are acquired by optical-mechanical scanners and special videocon systems, but not by film. Microwave 0.1 to 30cm Longer wavelengths can penetrate clouds, fog, and rain. Images may be acquired in the active or passive mode. Radar 0.1 to 30 cm Active form of microwave remote sensing. Radar images are acquired at various wavelength bands. Radio >30 cm Longest wavelength portion of the electro-magnetic spectrum. Some classified radar with very long wavelength operate in this region.

13 Makes use of sensors that detect the reflected or emitted electro-magnetic radiation from natural sources, most notably the sun. Due to its surface temperature of 5800K, the sun emits most of its energy in the visible part of the spectrum. The earth with a surface temperature of 300K emits most of its energy in the thermal part of the spectrum.

14 Spectral emission, atmospheric transmittance and sensor sensitivity Figure (3a) Energy Source Figure (3b) Atmospheric Transmittance Thermal Scanners Figure (3c) Common Remote Sensing Systems

15 Atmospheric Transmittance

16 Interaction between EMR and surfaces

17 Spectral Reflectance Curves

18 Vegetation reflectance curves Chlorophyll absorption Water absorption

19 Mineral Reflectance curves

20 Remote Sensing Systems DATA ACQUISITION DATA ANALYSIS Reference data Pictorial Visual Numerical Quantitative Users Sources of energy Propagation through atmosphere Sensor systems Data products Interpretation procedures Re-transmission through atmosphere Information products Reflection on surface features

21 Platforms Platform Altitude Observation Remarks geostationary satellite 36,000km fixed point observation GMS circular orbit satellite (earth observation) 500km - 1,000km regular observation LANDSAT, SPOT, MOS, etc space shuttle 240km - 350km irregular observations radio - sound 100m - 100km various investigations (meteorological, etc) high altitude jet-plane 10km -12km reconnaissance, wide area investigations low or mid altitude plane 500m - 8,000m various aero investigation surveys helicopter 100m- 2,000m various aero investigation surveys radio-controlled plane below 500m various aero investigation surveys aeroplane, hang-plane m various aero investigation surveys hangglider hang-balloon 800m - various investigations cable 10-40m archaeological investigations crane car 5-50m close range surveys ground measurement car 0-30m ground truth cherry picker

22 Earth Observation Satellite Orbits GROUND TRACK ALTITUDE = 705 KM (Nominal) INCLINATION = 98.2 O Equator crossing: 9:45am (Local time) DIRECTION OF TRAVEL ORBIT PERIOD = 98.9 MINUTES

23 Earth Observation Satellite Orbits / 2

24 Sensors A sensor or remote sensor is a device to detect the electro-magnetic radiation reflected or emitted from an object. Cameras or scanners are examples of remote sensing-sensors.

25 Sensors: Solid State Scanners

26 Sensors: Opto-Mechanical Scanner

27 Characteristics of RS systems: Resolution In general, resolution is defined as the ability of an entire remote-sensing system, including lens, antennae, display, exposure, processing, and other factors, to render a sharply-defined image. Resolution of a remotesensing system is of different types. (1) Spectral Resolution (2) Radiometric Resolution (3) Spatial Resolution (4) Temporal Resolution

28 Spectral Resolution Detectors Incoming light (mix of different wavelengths) Prism or Spectrometer

29 Spectral Resolution / 2 coarse spectral resolution: only 1 value, same for soil and turbid water finer spectral resolution: 3 values, each is different for soil / water

30 Spectral resolution of some RS systems SPOT Pan SPOT XS Landsat TM NOAA AVHRR IRS LISS IRS WiFS ADEOS AVNIR

31 Spectral Band Range (µm) used in Thematic Mapper (TM) onboard Landsat's 4 and 5 sensor system and their potential application Band Band Range Number (µm) Potential applications to 0.52 coastal water mapping; soil/vegetation differentiation; deciduous/coniferous differentiation (sensitive to chlorophyll concentration); etc to 0.62 green reflectance by healthy vegetation; etc to 0.69 chlorophyll absorption for plant species differentiation; to 0.90 bio-mass surveys; water body delineation; to 1.75 vegetation moisture measurement; snow/cloud differentiation; to 12.5 plant heat stress management; other thermal mapping; soil moisture discrimination; to 2.35 hydrothermal mapping; discrimination of mineral and rock types;

32 Spectral Band Range (µm) used in Advance Very High Resolution Radiometer (AVHRR) sensor onboard NOAA Satellite system and their potential application. CHANNEL WAVE LENGTH) USES NUMBER (µm) CHANNEL cloud delineation, weather snow and ice mapping and monitoring, etc. CHANNEL surface water delineation, vegetation and agriculture assessment, range surveys, etc. CHANNEL land/water distinction, sea surface temperature, hot spot detection (forest fires and volcanic activity),etc. CHANNEL day/night cloud mapping, sea and land surface temperature, soil moisture, volcanic eruption, etc. CHANNEL sea surface temperature measurement, soil moisture, weather, etc.

33 Multispectral images: Landsat TM TM6 ( )

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35 Spatial resolution / 2 Landsat MSS (80m) SPOT XS (20m) IRS Pan (6m) KVR (2m) SPOT Pan (10m) Landsat TM (30m) IRS WiFS (188m) NOAA AVHRR (1.1km)

36 Spatial Resolution SATELLITE SYSTEM SOME OPTICAL SENSOR SYSTEM LANDSAT 4/5 MSS LANDSAT 4/5 TM SPOT XS NOAA AVHRR MOS MESSR JERS OPS VINR and SWIR ADEOS AVNIR IRS-1C LISS-III IRS-1C WiFS Spatial Resolution 80 m 30 m 20 m 1.1 km (LAC) 50 m 18 m X 24 m Off-nadir viewing SPOT PAN JERS (side-look) (10m OPS capability for the resolution) VINR (PAN) µm (18m X Panchromatic 3 days revisit 24m) mode for stereo capability Bands 3 & image data 4 acquisition) µm 16 m 24 m 188 m (200 m) ADEOS IRS-1C PAN AVNIR (6 m PAN resolution) (8 m (70 km swath Resolution) width) µm 0.72 µm (6-bit)

37 Spatial resolution: TM and SPOT Pan

38 Temporal resolution SATELLITE LANDSAT LANDSAT SPOT NOAA MOS JERS ADEOS IRS-1C IRS-1C SYSTEM MSS TM XS AVHRR MESSR OPS AVNIR LISS-III WiFS VINR AND SWIR Revisit Cycle (nadir) 1 image/day (nadir) 24 (nadir) (in days)

39 Quantization level of remote-sensing data Sensor Satellite Level (bit) Descriptions MSS LANDSAT 6 8 bits data after radiometric correction TM LANDSAT 8 HRV (XS) SPOT 8 HRV (PA) SPOT 6 AVHRR NOAA 10 both 10 and 16 bits data are available at distribution SAR JERS-1 3 real 3 bits, imaginary 3 bits

40 Remote Sensing Satellite The remote sensing satellites are equipped with sensors looking down to the earth. They are the "eyes in the sky" constantly observing the earth as they move around the earth. Remote Sensing Satellite Remote Sensing satellite images gives a synoptic (bird s eye) view of any places of the Earth surface, which helps to study, map, and monitor the Earth s surface at local and/or regional/global scales. It is cost effective and gives better spatial coverage as compared to ground sampling.

41 Types of Remote Sensing Images There are several remote sensing satellite series in operation. Different satellite systems have different characteristics, e.g. resolutions, number of bands, and have their own importance for different application. Satellite Systems Spatial Resolution Type Number of Bands Launched by LANDSAT-ETM+ LANDSAT-TM LANDSAT-MSS SPOT-XS SPOT-PAN IRS-1C PAN IRS-LISS-III IRS-WiFS Cosmos -KVR1000 IKONOS IKONOS ADEOS-AVNIR M NOAA AVHRR MOS MESSR 15,30,50 30m 80m 20m 10m 6m 24m 188m 2m 1m 4m 16m 1.1Km 50m Multi-spectral Multi-spectral Multi-spectral Multi-spectral Panchromatic Panchromatic Multi-spectral Multi-spectral Panchromatic Panchromatic Multi-spectral Multi-spectral Multi-spectral Multi-spectral USA USA USA France, Sweden France, Sweden India India India Russia/USA Canada Canada Japan USA Japan

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43 SATELLITE LANDSAT LANDSAT4/5 SPOT NOAA MOS JERS ADEOS IRS-1C IRS-1C SYSTEM 4/5 TM XS AVHRR MESSR OPS AVNIR LISS-III WiFS SOME VINR MSS OPTICAL and SENSOR SWIR SYSTEM Spectral Resolution (Number of Bands) Four Seven Three Five Four Seven Four Four Two Spectral ranges (wave-length portion of EMR) in µm (micrometers) Blue Green Red NIR NIR IIR IIR IIR (MIR) IIR (MIR) ThIR FIR

44 Remote Sensing Images Remote sensing images are normally in the form of digital images. Image processing techniques are applied to enhance the image to help visual interpretation, information extraction and to correct or restore the image if the image has been subjected to geometric distortion, blurring or degradation by other factors. There are many image analysis techniques available and the methods used depending upon the requirements of the specific problem concerned. Satellite Image of Kathmandu