What is image point displacement? What is the law of image point displacement?

What is image point displacement? What is the law of image point displacement? As follows:

Image point displacement refers to the phenomenon that the position of the image point in the photo deviates due to the tilt of the photo or the fluctuation of the ground in photogrammetry. The displacement of the image point has a certain law, which mainly depends on factors such as the inclination angle of the image, the distance from the image point to the main point, the direction angle and so on.

Aerial photographs are the central projection of the ground. According to the principle of central projection, no matter the undulating terrain or any object above the ground, the image points reflected on aerial photographs generally move relative to their plane positions, which is called image point displacement.

It is mainly caused by the tilt of the photo, the height difference of the ground point relative to the datum plane and physical factors (such as deformation of photographic materials, flattening error, distortion of photographic objective, atmospheric refraction and curvature of the earth, etc.). ).

In the engineering field, the law of image point displacement is of great significance to photogrammetry and remote sensing technology. By studying the law of image point displacement, the photos can be corrected and the measurement accuracy and accuracy can be improved. In addition, the law of pixel displacement is also applied to geological exploration, topographic survey, urban planning and other fields to help solve practical problems and provide accurate spatial information.

Regarding the law of image point displacement, the following are some common situations:

1, the displacement of image points is evenly distributed on the radiation line centered on the isocenter, that is, the displacement of image points on the direction line starting from the isocenter is equal.

2. On the isochromatic line, that is, at the intersection of the oblique photo and the horizontal photo, the displacement of the image point is zero, and there is no displacement of the image point.

3. When the inclination angle is between 0 ~180, the displacement of the image point is negative and faces the direction of the isocenter.

4. When the inclination angle is between180 ~ 360, the displacement of the image point is positive, facing away from the isocenter.

5. In an inclined photograph, the displacement of the image point is related to the inclination angle, the distance from the image point to the main point and the direction angle.