Tag Archives: Image Sensor

Another important role of these photos is to provide a foundation for collecting the spatial information needed. Data in the form of the satellite images or aerial photographs must be taken without any distortions, if you need to gather information useful for a mapping or GIS system in the case of roads, marine forms or vegetation.This process of correcting the distortions of a satellite image of aerial photograph is called orthorectification. This process allows you to make direct and precise measurements of areas, distances, angles, positions etc.Why an aerial photograph needs correction?The main challenge of an aerial photograph compared to a non-aerial photograph is that an aerial photograph needs perspective correction. An aerial photo is usually captured at an angle to the object being photographed. Here, the perspective of the photograph will be incorrect with near objects compared to distant objects. By perspective correction, the objects in the image and the real world will have equal size.procedure of OrthorectificationAs topographical variations in earth’s surface and the tilt of the satellite or the aerial sensors can affect the display of the features on the satellite or aerial image with regard to their distance. The image distortion will be more as the topographical diversity of the landscape is more.Image data acquired by airborne and satellite image sensors are affect by systematic sensor and platform-induced geometry errors, which introduce terrain distortions when the image sensor is not pointing directly at the Nadir location of the sensor.There can be hundreds of meters of terrain displacement. Image data over an area with at least a kilometer of vertical relief, with the sensor having an elevation angle of 60° (30° from Nadir), the image output will have nearly 600 meters of terrain displacement.Errors in setting the reference elevation