Ortofotoihin

Ortofotoihin, often translated as orthophotos, are aerial or satellite images that have been geometrically corrected to remove distortions caused by camera tilt, terrain relief, and perspective. Unlike standard aerial photographs, orthophotos represent a true-to-scale map, meaning that measurements of distance, area, and shape can be accurately taken from them. This geometric correction is achieved through a process called orthorectification, which uses a digital elevation model (DEM) of the terrain to adjust the image.

The creation of orthophotos involves several steps. First, aerial or satellite imagery is captured. This raw imagery is then georeferenced, meaning its position on the Earth's surface is precisely known. A digital elevation model is then used to model the terrain's topography. The orthorectification process then uses this DEM to remove the geometric distortions present in the raw image, effectively projecting the image onto a flat plane as if it were taken directly from above at every point.

Orthophotos have a wide range of applications. They are invaluable in cartography for creating accurate maps, in land surveying for precise boundary definition, and in urban planning for detailed analysis of built environments. They are also used in environmental monitoring to track changes in land cover, in agriculture for precision farming, and in emergency management for disaster response planning and assessment. Their ability to combine the visual detail of an image with the geometric accuracy of a map makes them a powerful tool in numerous fields.