Orthorectification is a process of removing distortion from an image caused by the curvature of the Earth and changes in terrain. It involves correcting the perspective of the image to align it with a map or a coordinate system, resulting in a more accurate representation of the Earth's surface.

In simpler terms, imagine taking a picture of a city from an airplane window. The buildings closer to you appear larger, while those further away appear smaller. Additionally, the curved shape of the Earth causes the image to appear distorted. Orthorectification corrects for these distortions so that the image accurately reflects the size and location of objects on the Earth's surface.

Orthorectification is particularly important in satellite imaging, where images are often captured from high altitudes, resulting in significant distortions. By orthorectifying these images, analysts can more accurately measure distances, areas, and other features on the Earth's surface.

One common use case for orthorectification is in the creation of maps. Maps require accurate representations of the Earth's surface, and orthorectification helps to correct for distortions in satellite imagery to create more precise maps.

Another use case for orthorectification is in environmental monitoring, such as tracking changes in vegetation or water resources. By aligning satellite imagery with geographic data and correcting for distortions, analysts can track changes over time with greater accuracy.

Overall, orthorectification is an essential step in satellite imaging and helps to ensure that the data collected is accurate and useful for a wide range of applications.