Data acquisition through Satellite Remote Sensing
Transcript of Data acquisition through Satellite Remote Sensing
Dr. Muhammad Shafique
NCE in Geology
INTRODUCTION TO REMOTE SENSING
Remote Sensing
Remote Sensing is:
The art and science of obtaining spatial information about an object or phenomenon without being in direct contact with the object (Jensen 2000).
The collection of information about Earth surfaces and phenomena using sensors not in physical contact with the surfaces and phenomena of interest.
Remote Sensing
Remote Sensing
History of Remote Sensing
The history of remote sensing began with the invention of photography. The term "photography" is derived from two Greek words meaning "light" (phos) and "writing" (graphien).
1858 - Gasper Felix Tournachon “Nadar" takes the first aerial photograph from a captive balloon from an altitude of 1,200 feet over Paris.
History of Remote Sensing
1860's - Aerial observations, and possible photography, for military purposes were acquired from balloons in the wars. Balloons were used to map forest in 1862.
History of Remote Sensing
1903 - The Bavarian Pigeon Corps uses pigeons to transmit messages and take aerial photos.
History of Remote Sensing
1914-1918 - World War I
1908 - First photos from an airplane
History of Remote Sensing
1914 - WWI provided a boost in the use of aerial photography,
but after the war, enthusiasm waned
History of Remote Sensing
1946 - First space photographs from V-2 rockets.
1954 - U-2 takes first flight.
History of Remote Sensing
1957 - Russia launches Sputnik-1, this was unexpected and encouraged the rest of the world for race of space exploration.
History of Remote Sensing
Late 1960's - Gemini and Apollo Space photography.
History of Remote Sensing
Energy Source or Illumination (A) Radiation and the Atmosphere (B) Interaction with the Target (C) Recording of Energy by the Sensor (D) Transmission, Reception, and Processing (E) Interpretation and Analysis (F) Application (G)
Source: Canadian Centre for Remote Sensing
Remote Sensing process components
1.ENERGY SOURCE (PASSIVE SYSTEM): sun, irradiance from earth’s materials; (ACTIVE SYSTEM):
irradiance from artificially-generated energy sources such as radar)
2.PLATFORMS (Vehicle to carry the sensor) (truck, aircraft, space shuttle, satellite, etc.) 3.SENSORS (Device to detect electro-magnetic radiation) (camera, scanner, etc) 4.DETECTORS (To convert electro-magnetic radiation into recorded signals) (film, silicon detectors, etc) 5.PROCESSING (Handling signal data) ( photographic, digital) 6.INSTITUTIONALISATION (Organization for execution at all stages of remote-sensing technology: international and national organizations, centers, universities, etc
Remote Sensing process components
Visual
Quantitative
(i)Users
(e) Sensing systems (f)Data products (g) Interpretation
procedures
(h) Information
products
Reference
data
Pictorial
Numerical
DATA ACQUISITION DATA ANALYSIS
( a) Sources of energy
( c)Earth’s surface features
(d) Re-transmission
through the atmosphere
(b) Propagation
through the
atmosphere
Remote Sensing process components
A technology used for obtaining information about a target through the analysis of data acquired from the target at a distance.
Applications
Remote Sensing process components
Types of Remote Sensing
There are two main types of Remote sensing: a. Passive Remote Sensing: Makes use of sensors that detect the reflected or emitted electro-magnetic radiation from natural sources. b. Active remote Sensing: Makes use of sensors that detect reflected responses from objects that are irradiated from artificially-generated energy sources, such as radar.
Remote sensing
Information extracted from remote sensing images depend on type of energy the remote sensing system detect
Energy detected by remote sensing system is electromagnetic energy
All objects with temperature above absolute zero temperature continuously emit electromagnetic radiation
Where: absolute zero on Kelvin temp scale is equivalent to -273⁰ C and -459.7⁰ F.
(E) Electric Field, (M) Magnetic Field, (C) Speed of Light
Electromagnetic radiation consists of an electrical field (E) which varies in magnitude in a direction perpendicular to the direction in which the radiation is traveling, and a magnetic field (M) oriented at right angles to the electrical field. Both these fields travel at the speed of light (c).
Electromagnetic radiation
Electromagnetic waves are produced by the motion of electrically charged particles. These waves are also called "electromagnetic radiation" because they radiate from the electrically charged particles. They travel through empty space as well as through air and other substances.
Electromagnetic radiation
Electromagnetic radiation
Wave Terminology
Wavelength - distance between two like points on the wave
Amplitude - the height of the wave compared to undisturbed state
Period - the amount of time required for one wavelength to pass
Frequency - the number of waves passing in a given amount of time
Electromagnetic Spectrum
Electromagnetic Spectrum
Resolution
Resolution determine the ability of remote sensing data to distinguishing between different objects.
Types of resolution
Spatial resolution is a measure of the smallest object that can be resolved by the sensor, or the linear dimension on the ground represented by each pixel or grid cell in the image
Spectral resolution describes the specific wavelengths that the sensor can record within the electromagnetic spectrum.
Temporal resolution is a description of how often a sensor can obtain imagery of a particular area of interest. For example, the Landsat satellite revisits an area every 16 days as it orbits the Earth, while the SPOT satellite can image an area every 1 to 4 days.
Radiometric resolution refers to the number of possible brightness values in each band of data and is determined by the number of bits into which the recorded energy is divided. In 8-bit data, the brightness values can range from 0 to 255 for each pixel (256 total possible values). In 7-bit data, the values range from 0 to 127, or half as many possible values.
Spatial resolution
I m resolution 2 m resolution 5 m resolution
10 m resolution 20 m resolution 30 m resolution
Spatial resolution refer to smallest feature differentiable on an image
ALI 30m
9 bands
Hyperion 30m
242 bands
TM 30m
6 bands
ASTER
15m VNIR, 30m SWIR
9 bands
MIVIS 8m
102 bands
IKONOS 4m
4 bands
Characteristics of different images
100 meter resolution
30 meter resolution
5 meter resolution
Spectral Resolution
Number and width of spectral bands recorded by an image
Only one band covering BGR visible range
called panchromatic
Spectral Resolution
Spectral Resolution
8-bit (0 - 255)
9-bit (0 - 511)
10-bit (0 - 1023)
0
0
0
The sensitivity of remote sensing detectors to differences in signal strength or brightness level it detects. Higher sensitivity finer the R.R. Measured in levels of data storage units
Radiometric Resolution
Radiometric resolution
8-bit quantization (256 levels) 6-bit quantization (64 levels)
4-bit quantization (16 levels) 3-bit quantization (8 levels)
2-bit quantization (4 levels) 1-bit quantization (2 levels)
Temporal Resolution
Frequency of image acquisition,
Or revisit time
Application of Temporal images
Nowshera city, 2010 Before flood After flood
Different Types of Satellite Images
LAND SAT
SPOT
KOMET
IKONOS
QUICK BIRD
LANDSAT (USA)
Bands:7
Resolution:30m
Area Covered: 185x 185 Km
SPOT (France)
Band : 3
Resolution:
Pan:10 m
XS: 20 m
Area Covered:
60 x 60 m
Kometa (Russia)
Bands: Only Panchromatic
Resolution: 2 m
Area Covered:
40 x 40 Km
IKONOS (USA)
Band : 3
Resolution:
Pan:1 m
MS: 4 m
Area Covered:
11 x 11 Km
Quick Bird (USA)
Band : 3
Resolution:
Pan:0.61 m
MS: 2.44 m
Area Covered:
13.5x13.5 m
Integration of Remote sensing and GIS
Integration of Remote sensing and GIS
Remote sensing provides a regional view It enable us to observe & measure the causes & effects of climate &
environmental changes (both natural & human-induced)
Remote sensing provides repetitive geo-referenced looks at the same area
Remote sensors “see” over a broader portion of the spectrum than the human eye
Sensors can focus in on a very specific bandwidth in an image
They can also look at a number of bandwidths simultaneously
Some remote sensors operate in all seasons, at night, and in bad weather
Advantages of Remote sensing