Calculation formula of photographic datum

The calculation formula of photographic benchmark is as follows:

The calculation formula of photographic reference usually involves many parameters and variables, including the internal orientation elements and external orientation elements of the camera and the transformation between the image plane coordinate system and the image space coordinate system. The following is an example of a simple formula for calculating photographic data:

The transformation relationship between image plane coordinate system (X image plane, Y image plane) and image space coordinate system (X image space, Y image space, Z image space) is as follows:

X image blank = k 1 * x image plane +k2 * y image plane +k3.

Y image blank = k4 * x image plane +k5 * y image plane +k6

Z image blank = k7 * x image plane +k8 * y image plane +k9

Among them, k 1, k2, ..., k9 are internal orientation elements, which describe the geometric characteristics of the internal optical system of the camera, such as lens distortion, optical center position, etc. These parameters usually need camera calibration.

The conversion relationship between the image plane coordinate system (X image plane, Y image plane) and the ground (or datum plane) coordinate system (X ground, Y ground) is as follows:

X ground = a 1 * x image plane +a2 * y image plane +a3.

Y ground = a4 * x image plane +a5 * y image plane +a6

Among them, a 1, a2, ... a6 are external orientation elements, which describe the position and direction of the camera relative to the ground (or datum). These parameters usually need to be determined according to the actual photogrammetry task.

By establishing the above two conversion relations, the conversion formula between the ground coordinate system and the image space coordinate system can be obtained:

X ground = (k1* a1+k2 * a2+k3) * x image plane +(k 1 * a4+k2 * a5+k3) * y image plane+(k1* a3+k2 * a6+.

Y ground = (k4 * a 1+k5 * a2+k6) * x image plane +(k4 * a4+k5 * a5+k6) * y image plane +(k4 * a3+k5 * a6+k6).