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- sensor of
By any means electromagnetic radiation reflected from different phenomena, or other energies emitted (eg, infrared and thermal waves) collected form suitable for obtaining information from the environment to provide, called sensor.
Sun is a very important energy source for remote sensing is reminded that the power of the sun as a visible wave reflection is gaining illusion as heat waves, infrared radiation absorbed is gaining. All remote sensing systems energy are measured. Thus, by any means that energy electromagnetic radiation reflected from different phenomena or other energy emitted (such as heat waves, infrared) to collect objects and information to the appropriate form of the phenomenon or object offers, called sensor be. In other words, that the sensor device to measure the energy reflected from an object looks. With the obvious definition is that a camera is a sensor. Most sensor in one or more of the electromagnetic spectrum range are capable of imaging.
As the first article came to the main components of a remote sensing system consists of phenomena, energy source, transmission route (atmosphere) is in fact, the two main target but transfer all remote sensing systems have been common other major components, i.e only energy source and type of sensor is used. With this description, sensor remote sensing based energy source can be used in two broad categories of active non active can be divided.
non-active sensor
Remote sensing systems measure their energy, if this energy source systems normally be accessible, in terms of the passive sensor (passive) say. In other words, non-active sensor can only reflect the energy that normally a source of energy (mainly solar) is ongoing to measure. Therefore, this sensor have their own generating electromagnetic energy could send it toward the phenomenon, but the energy reflected from various earth phenomena are of electromagnetic radiation that the sun has been approved to collect. Thus the efficiency of this sensor is limited to the time when the sun clarifying hemisphere earth. collection information in terms of such a method called passive remote sensing. day with different cameras and TM multi-spectral scanner PAN disabled is done, Microwave sensor can be disabled at a wavelength of millimeters to a meter to imaging.
Active sensor
The sensor, the energy source of their supply Vdaray are generating electromagnetic energy. Most active remote sensing systems in waves, visible, infrared, thermal infrared and micro-waves (small) range of electromagnetic energy work. They are capable waves under any circumstances within the atmosphere, land or waters deep penetration give sizes of waves are collected. So that the first phenomenon of electromagnetic energy toward the desired sent collect, record is. For example, camera with flash after sending the light to the phenomenon, it reflects light or radiation can record TFG collected. This collect data in the term remote sensing is called active.
Radar image can be prepared during the night or day, cloudy or rainy style does. None of these factors affect image quality can not do it. Of course, to note that the phenomenon of surface texture in radar images is very important. Most of the radar waves are used, with wavelength equal to 3 / 3 8 / 0 are cm. more radar images for analysis of land use map some land, mostly covered by clouds, like a tropical forest belt usage are convergent.
In addition, sensor output data also can be another criterion for classification because they are all the result output remote sensing systems are not the same. Thus, different sensor remote sensing can be based on efficiency information, two broad categories of non-imaging sensor imaging be divided.
All systems available remote sensing information about the kind of things give us. The output of all these systems together is not a type but depending on the type of sensor uses is different. Efficiency of information systems, some of these images or pictures into had called them And at image sensor or imaging say. But the second group to yield information on a series of charts and statistical tables to the ability to convert image files and they do so in terms of non-visual sensor imaging or non-call.
- Non-imaging sensor
Photometry, ray spectrometer and a part of non-imaging sensor that is light and electromagnetic waves to the depths of the earth, waters and skies are sent. Then they reflections were measured and recorded and output informations as graphs and tables are visible. Then, commentators and experts with comparison charts and figures follow changes in the status and conditions governing the phenomena are desired.
- Imaging sensor
The image sensor used in most remote sensing are. Because of their ability to convert output data to the portrait and his group are divided into the following:
A) sensor illustrated by (Pictural Sensors)
Cameras first and the most popular sensor data such that their efficiency is directly converted to images. Pictures that cameras with different films are prepared at wavelengths between 4% and 9% are in microns. Main profile and important cameras in remote sensing are used include: Film, focal distance briefly in the following descriptions about them is.
Focal length: focal distance is to the distance between the center lens Vfylm files when the set is infinite. Focal aerial photographs in addition to short-hundredth mm digits are printed.
Film: Picturing the effects of surface the film is used. Construction of multi-layer film formed part of every layer, it is sensitive to electromagnetic spectrum. Considering the number of layers and disease-sensitive film in building them in the three groups have divided into the following major and briefly about their descriptions will be given.
A) Black and White Film. Including films infrared are Black and White.
B) conventional color films or natural color. This film than all the visible range of the electromagnetic spectrum sensitive layer sensitive to their three bands, blue, green, red and finally formed the natural color show. So that all images produced in white light with color natural phenomena seem like nature.
C) virtual or pseudo-color film, these movies have the green light sensitive layer was red in the picture into a different color blue, green, red can be.
Color objects in the image obtained with these films depends on the percentage of green color red phenomenon is reflected. Green Plants in false color photographs dark red appear, because the color green and infrared Red are closely reflected the blue color of these two plus the red into dark red (Magenta) is.
Filter: filter or filters of an important role in collecting information is on film. Filter function that radiation from entering those that are needed to prevent. Thus for the radiation phenomenon is considered to complete the self-crossing gives.
For example, filter camera means that part of the absorption wavelengths and the rest will pass to his or that depending on the type of filter to only a part of the electromagnetic spectrum is transparent to the rest of the opaque acts.
Cameras have different types of aerial photographs that are used.
B) numerical and digital sensor
Sensor information those mentioned as a series of figures and numbers, most applications are in remote sensing science. Sensor of digital platforms are mainly based on space satellites are installed, especially to restore the platform to ground level is not. Because Data can be easily transmitted to ground receiving stations will be. So that the reflected waves from various phenomena in the sensor system to assist an electrical signal converted and after registration in opportunity to be transmitted to Earth. Sometimes the act is done directly. Record TFG data collection system of the sensor illustrated with imaging sensor was almost one major their output and efficiency has informations. Because the efficiency of digital sensor data due to lack of film within the sensor directly into the portrait is not. During the process, but a special ability to convert the images have become, or through television pictures cholera special computer method, analyzed and can be used by users.
Numerical or digital sensor, optical sensor - are also called mechanical. Firstly, because the optical range of electromagnetic spectrum, ie 3 / 0 to 15 micrometers work. Secondly, the mechanical in this regard are that this sensor, the mirror to the help of a mirror like Landsat engine, which is 819 times per minute during , comes to the swing.
Surveyor of the subject sensor TM, multi-spectral scanning Manufacturer OCM, HRV, LISS, PAN, MSS and ..... On a remote sensing satellites have been installed all kind of numerical or digital sensor are
C) sensor system MMS multi-spectral scanning Manufacturer (Multispectral Scanner)
Scan of lexical word meaning to see, record or broom is (1985) the sensor system are the definition of such ((a subject of any vision system, its effects on Earth's surface or more than one wavelength electronically or to scan electromagnetic)). Therefore sensor is a multi-spectral sensor simultaneously from several narrow spectral bands (visible bands ranging from infrared band) to imaging. This sensor, the Earth's surface are as narrow line scan direction perpendicular Satellite flight path (platform).
The sensor, a movable mirror that swings per second 6 / 13 times, as much as 9 / 2 ± ° or totaling 8 / 5 degrees has fluctuated. Mirror movement from West to East is. Ie to move from West to East to shoot. Radiation reflected from a bar width of 24 meters to six smaller bar, the width of 4 meters are divided into the mirror to mirror reached optical sensor system is transferred. During this 24-meter strip that is perpendicular path through the satellite, is 11 miles.
Optical sensor system, built to mirror focus rays after they received Charter, the stability of conductivity sensor, and there are converted into electrical signal and then reinforced, or on tape recordings (up to the time the proper exposure in the field of satellite ground stations, to be transmitted to Earth) or that are transmitted directly to Earth. MSS sensor or scan multi-spectral Satellite user range are four bands. in every bar band at six photographs is. Therefore, a total of 24 = 4 * 6 stability has been installed.
Multi-spectral sensor scans the user satellite field of vision Series moment (IFOV) equal to 4 x 4 meters on the earth. Ie at any given moment about a piece of land with dimensions of 4 x 4 m mirror reaches . But due to the joint covering parts 4 x 4 meters this information to the dimensions of less than 4 x 4 m on the registers are stored in each of these parts they called pixels. Therefore, the equivalent of 16 square meters per pixel dimensions or to an ordinary bedroom on the ground. Number of pixels in each image of MSS for X axis of each number is approximately 2750. In other words, the total number of pixels in a satellite MSS size 11 * 11 km on the ground level is equal to the number 7562500 in Vchvn is quad-band imaging, imaging at each more than 30 million value of the information to be recorded in digital form. This 4 x 4 square meters, which reflected ray data from the MSS system will be recorded separately, resolution, or ground form (GRE) also called. Ie at least an area of land that is detectable. For example, the sensor of a digital information that armored military dimensions of 4 x 4 meters in a pixel can record TFG and recording it as a value in the data because is quad-band imaging. Totally worth the four information is registered by the sensor.

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sensor of    mss    field of vision series moment    multispectral scanner    magenta    pictural sensors