Image Processingĭue to the size of the Earth, the nature of imaging sensors, and the pure volume of images that need to be taken, image processing is required to make useful images. Each satellite will be produced with a specific task in mind (or multiple tasks). So, you can see that satellites are highly specialized pieces of equipment. If a satellite is being used to monitor a certain area, it will take a certain number of hours for the satellite to reach that location over the Earth again. This refers to the amount of time between images for a particular location. Unlike normal cameras, satellites also have temporal resolution. But this isn’t all satellites are able to do. In this way, a satellite featuring sensors that can capture visible and infrared light will be able to differentiate between different environments on the planet’s surface. For instance, snow reflects all radiation quite strongly, whereas dense vegetation will absorb a lot of red light but emit infrared light. Electromagnetic radiation includes visible light (like we see through our eyes), infrared, and ultraviolet light. Different structures on Earth reflect electromagnetic radiation differently, which is what allows satellites to be so useful. The spectral resolution, on the other hand, is what kinds of light the sensor can capture. For instance, if the satellite is orbiting north-to-south, it may have a sensor or mirror that moves in the opposite direction to “scan” a broader area as it moves. That means that in order to capture images of a broad area, either the sensor must be able to move or there must be an array of sensors. Keep in mind that satellites are constantly in motion. Some sensors are able to capture a resolution of up to 0.31 meters squared per pixel, though most will not have a resolution that fine. This is basically how much area is able to be captured by the sensor at a time, or how many and how small its pixels are. Every sensor will have a certain spatial resolution. Like a normal camera, different satellite sensors have different capabilities. On the other hand, active sensor satellites emit their own radiation and analyze it as it reflects back to the satellite. Passive sensor satellites collect data about the Earth via electromagnetic radiation that is emitted by the sun and reflects off the Earth. These are active sensors and passive sensors. There are two broad categories of imaging satellites’ sensors. Here are some of the ways that satellites and their sensors can vary. There are different kinds of sensors and different methods for acquiring satellite images.
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