Characteristics of remote sensing

1, large-area synchronous observation (large scale)

Remote sensing detection can observe the earth in a large area from the air or even space in a short time and obtain valuable remote sensing data from it. These data expand people's visual space, such as a land satellite image with an area of over 30,000 square kilometers. This kind of macroscopic image is very important for analyzing the earth's resources and environment.

2. Timeliness and periodicity

The speed of obtaining information is fast and the period is short. Because the satellite orbits the earth, it can get the latest information of various natural phenomena passing through the region in time, so as to update the original information or carry out dynamic monitoring according to the changes of old and new information, which is incomparable to manual field measurement and aerial photogrammetry.

For example, Landsat 4 and 5 can cover the earth once every 16 days, and NOAA meteorological satellites can receive images twice a day. Meteorological satellites acquire images of the same area every 30 minutes.

3. Data are comprehensive, comparable and binding.

Remote sensing detection can dynamically reflect the changes of things on the ground, and can periodically and repeatedly observe the same area, which is helpful for people to discover and dynamically track the changes of many things on the earth through the obtained remote sensing data.

At the same time, study the changing law of nature. Especially in monitoring weather conditions, natural disasters, environmental pollution and even military targets, the application of remote sensing is particularly important.

The data obtained are comprehensive. At the same time, remote sensing data covering a large area are obtained. These data comprehensively show many natural and human phenomena on the earth, macroscopically reflect the shape and distribution of various things on the earth, truly reflect the characteristics of geology, geomorphology, soil, vegetation, hydrology, artificial structure and so on, and comprehensively reveal the correlation between geographical things. And these data have the same trend in time. ?

There are many means to obtain information, and the amount of information is large. According to different tasks, remote sensing technology can choose different bands and remote sensing instruments to obtain information. For example, visible light can be used to detect objects, and ultraviolet, infrared and microwave can also be used to detect objects.

Using the different penetrability of different wave bands to objects, we can also obtain the internal information of ground objects. For example, the microwave band can also work around the clock in the depths of the ground, under the water, under the ice water body and under the desert.

4. Economic and social benefits

Access to information is less restricted by conditions. There are many places on the earth, where the natural conditions are extremely bad and it is difficult for human beings to reach, such as deserts, swamps and mountains. Using remote sensing technology, especially space remote sensing, which is not limited by ground conditions, can obtain all kinds of valuable information conveniently and timely.

5. Limitations

At present, the electromagnetic waves used in remote sensing technology are still very limited, only a few bands. In the electromagnetic spectrum, there are still many spectrum resources to be further developed. In addition, the used electromagnetic spectrum can not accurately reflect some characteristics of many ground objects, so it is necessary to develop high spectral resolution remote sensing and other means besides remote sensing, especially ground investigation and verification.

Extended data:

Remote sensing is a comprehensive earth observation technology, and its realization requires not only a set of technical equipment, but also the participation and cooperation of many disciplines, so the implementation of remote sensing is a complex system engineering. According to the definition of remote sensing, remote sensing system mainly consists of the following four parts:

1. Information source Information source is the target to be detected by remote sensing. Any target has the characteristics of reflecting, absorbing, emitting and radiating electromagnetic waves. When the target interacts with electromagnetic waves, the electromagnetic wave characteristics of the target will be formed, which provides the basis for obtaining information for remote sensing detection.

2. Information acquisition Information acquisition refers to the detection process of receiving and recording the electromagnetic wave characteristics of the target by remote sensing technology. Remote sensing technology and equipment for information acquisition mainly include remote sensing platforms and sensors. Among them, the remote sensing platform is a vehicle used to carry sensors, such as balloons, airplanes, satellites and so on. Sensors are instruments and equipment used to detect electromagnetic wave characteristics of targets, such as cameras, scanners and imaging radars.

3. Information processing Information processing refers to the technical process of correcting, analyzing and interpreting the obtained remote sensing information by using optical instruments and computer equipment. The function of information processing is to master or clear the errors of the original remote sensing information through the correction, analysis and interpretation of the remote sensing information, sort out and summarize the image characteristics of the detection target, and then identify and extract the necessary useful information from the remote sensing information according to the characteristics.

4. Information application Information application refers to the process that professionals apply remote sensing information to various business fields for different purposes. The basic method of information application is to use remote sensing information as the data source of geographic information system for people to query, count, analyze and use. Remote sensing has a wide range of applications, including military, geological and mineral exploration, natural resources investigation, map mapping, environmental monitoring and urban construction and management.

References:

Baidu Encyclopedia-Remote Sensing