What are the two main types of remote sensing?

The two main types of remote sensing are categorized as active and passive. Active remote sensing involves the emission of energy towards the target, which then reflects back to the sensor. Examples include radar and LIDAR systems, where the sensor actively sends out signals and measures the returned signals to gather information about the Earth's surface.

In contrast, passive remote sensing relies on the detection of natural radiation that is emitted or reflected by an object or scene. This method utilizes sensors that measure the energy from sources like the sun. Common examples of passive remote sensing include satellite imagery from optical sensors that capture sunlight reflected off the Earth's surface.

Understanding these two categories is fundamental because they determine how data is collected and the types of information available. While both types can provide valuable data for analyses and applications, they operate under different principles and are suited for different types of measurements and environmental conditions.