Is there a big error between the flying height and the actual height of the drone?

There is a big error between barometric altitude and GPS altitude, and the altitude on flight control is generally barometric altitude, which needs to be converted into local altitude through sea level barometric correction. Based on short-period counting, the long-period pressure is calculated relatively. So adding drift, vibration and air pressure changes will all become errors. UAV has been widely used in meteorological monitoring, land and resources law enforcement, environmental protection, remote sensing aerial photography, earthquake relief, express delivery and other fields. With the development of the Internet of Things, unmanned aerial vehicles (UAVs) have more and more applications in the Internet of Things technology. In order to better control the flight of UAV, the application of various sensors plays a very important role. Sensors that can measure height include barometer, accelerometer, gps, ultrasonic wave and so on! In flight control, complementary or Kalman fusion is usually used to fuse the data of these sensors and correct each other! Finally get the altitude of the plane! It is wrong to rely on the data of one sensor alone!