REMOTE SENSING
REMOTE SENSING DEFENTION:
• All operations which permit to gain information on something that has no direct
contact between it and the system which gets such information.
• It is the science which utilize reflected waves from objects on the earth,
atmosphere or from water covered areas (sea, oceans, etc) to bring information
on such objects.
• Remote sensing is the science of gathering information from a location that is
distant from the data source. Image analysis is the science of interpreting
specific criteria from a remotely sensed image.
• An individual may visually, or with the assistance of computer enhancement,
extract information from an image, whether it is furnished in the form of an
aerial photograph, a multispectral satellite scene, a radar image or a thermal
scan.
Thus the remote sensing we mean that we can get information from distant
objects resulting from the information or radiometric electromagnetic
instrumentations.
Active and Passive of remote sensing
instruments:
• In which information emitted from objects comes to the instrumnetatcon, such as:
1. Grouping it by the sensors and after transmitting it to the ground reception
stations.
2. Primary treatment of such information and subjecting them to corrections
followed by final treatment.
3. Interpretation of such information after covering them into photos.
4. Then using such photos to draw maps to serve several aspects.
• Passive instruments detect natural energy that is reflected or emitted from the
observed scene. Passive instruments sense only radiation emitted by the object
being viewed or reflected by the object from a source other than the instrument.
• Reflected sunlight is the most common external source of radiation sensed by
passive instruments. Scientists use a variety of passive remote sensors.
Platform definition:
• A platform is the vehicle or carrier for remote sensors for which they are borne. In
Meteorology platforms are used to house sensors which are obtain data for remote
sensing purposes, and are classified according to their heights and events to be
monitored.
PLATFORMS USED FOR REMOTE SENSING:
• A platform is the vehicle or carrier for remote sensors for which they are borne. They
are classified into three categories.
• • Ground-based (Extendable to a height of 15m above the surface)
• • Airborne (stratosphere 22-40 Km)
• • Space-borne (Space borne platforms range from 100 to 36000 km )
Stands for remote sensing instrumentation:
• The main purpose of such is to put the remote sensing instrument at certain level from
the earth’s surface in a direct balloon or in an aircraft to reasonable photos with suitable
scales.
• In some cases, spaces satellite can be used. Such satelltes move in a certain orbit
around the earth or by geostationary ones which stay will with respect to the earth.
Remote sensing space systems:
• This can be utlizied to get both civil and military information through the application of
remote sensing systems, in drawing maps ad for the prospection of natural resources
which have economic value.
• Remote sensing maps can also be used foe getting astrophysical data and for
navigation.
• Moreover, this can be utilized in military operations particularly for identification
proper objects to be attached and to get information on some strategic operations
of the enemy.
1. Mapping land areas in an economic rapid and consistent way.
2. Construction of possible means for continuous follows up.
3. Possible exploration of environmental changes.
4. Demarkation of geological setups in deserts and polar regions.
5. use of remote sensing information for getting digital information that can be
used easily in different aspects of studies.
Application or benefits of remote sensing
systems:
1. Estimation of natural resources
2. Pointing out sedimentary basins which filtrate techniques for oil, gas ore deposits.
3. Study places that can be considered to have underground water potentialities.
4. It can go well with the prospection of archeological sites.
5. It can play a very important role of in suppling important information on natural
hazards.
6. It helps much in protection of the environment and define areas where oil spots
occur.
7. It can be used in city planning.
8. It can be also used in agriculture purposes and is studying the physical mature of
water covered areas as for the suspended material is concerned.
Radiometer:
• An instrument that quantitatively measures the intensity of electromagnetic
radiation in some band of wavelengths in the spectrum. Usually a radiometer is
further identified by the portion of the spectrum it covers; for example, visible,
infrared, or microwave.
Imaging Radiometer:
• A radiometer that includes a scanning capability to provide a two-dimensional
array of pixels from which an image may be produced is called an imaging
radiometer. Scanning can be performed mechanically or electronically by using
an array of detectors.
Spectrometer
A device designed to detect, measure, and analyze the spectral content of the
incident electromagnetic radiation is called a spectrometer.
Conventional, imaging spectrometers use gratings or prisms to disperse the
radiation for spectral discrimination.
• Spectroradiometer
A radiometer that can measure the intensity of radiation in multiple wavelength
bands. Oftentimes the bands are of a high spectral resolution—designed for the
remote sensing of specific parameters such as sea surface temperature, cloud
characteristics, ocean color, trace chemical species in the atmosphere, etc.
Radar (Radio Detection and Ranging):
• A radar uses a transmitter operating at either radio or microwave
frequencies to emit electromagnetic radiation and a directional antenna
or receiver to measure the time of arrival of reflected or back scattred
pulses of radiation from distant objects.
• Distance to the object can be determined since electromagnetic
radiation propagates at the speed of light.
Scatterometer
• A scatterometer is a high frequency microwave radar designed
specifically to measure backscattered radiation.
• Over ocean surfaces, measurements of backscattered radiation in the
microwave spectral region can be used to derive maps of surface wind
speed and direction.
Active instrument:
• In which information emitted by instrumentation is reflected at
objects and registered by special types of sensors which transmit
it directly to the ground reception station.
• Active instruments provide their own energy (electromagnetic
radiation) to illuminate the object or scene they observe.
• They send a pulse of energy from the sensor to the object and
then receive the radiation that is reflected or backscattered from
that object.
Types of satellites:
What does image resolution mean?
• Resolution refers to the number of pixels in an image. Resolution is
sometimes identified by the width and height of the image as well as the
total number of pixels in the image.
• Higher resolutions mean that there more pixels per inch (PPI), resulting in
more pixel information and creating a high-quality, crisp image.
• Images with lower resolutions have fewer pixels, and if those few pixels are
too large (usually when an image is stretched), they can become visible like
the image below.
Resolutions of remote sensing
• 1. Spatial (what area and how detailed)
• 2. Spectral (what colors – bands)
• 3. Temporal (time of day/season/year)
• 4. Radiometric (color depth
