As an earth observation system, what are the characteristics of remote sensing compared with conventional means?

Compared with conventional means, remote sensing has the following outstanding features:

1. A wide range of data can be obtained. The flying height of aerial photography plane used for remote sensing is about 10km, and the satellite orbit height of land satellite is about 9 10km, which can obtain a wide range of information in time. For example, Landsat images can cover an area of more than 30,000 square kilometers. This kind of macroscopic image is very important for analyzing the earth's resources and environment.

2. 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. 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.

4. There are many ways to get information, and there is a lot of information. 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.