How to define image base point and image main point in photogrammetry? What's the difference between them?

1. The bottom point of the image, also known as the "vertical point of the image", is the vertical projection point of the camera center of the Landsat sensor on the earth's surface, which is represented by "n".

If the longitude and latitude of the image principal point C are exactly the same as the longitude and latitude of the image cardinal point N, it shows that the operating attitude of the land satellite completely meets the design requirements, but there are generally slight errors. If the error is too large, the product will be regarded as waste and cannot be supplied to the outside world.

2. The vertical line and intersection point of the photos taken by the photography center are the main points of the image. Generally speaking, the main point of the image is the center point of the photo, and its camera parameters are determined. Only the principal points of X and Yo images are used to determine the four-corner coordinates, that is, the size of the map and the internal direction of the photo.

The difference between the two:

1. The image principal point is the intersection of the principal optical axis and the image plane, and the image base point is the intersection of the vertical light and the image plane.

2. The bottom point of the image is used for the POS system to directly locate the ground target, and the main point of the image is used to determine the position on the topographic map.

3. The constraint of the bottom point of the image can be used as the control condition, but the constraint of the main point of the image can't.

Extended data:

Photography center: objective center

Main optical axis SO: the imaging plane perpendicular to S.

The intersection of the image principal point O:SO and the image plane

Inclination angle a: the included angle between the image plane and the ground plane.

Vertical line SN: a vertical line passing through s as the ground plane.

The intersection of image base point n:n:SN and image plane

The intersection of the underground point N:N:SN and the ground plane

References:

Baidu encyclopedia-adaptability measurement