pinhole camera
- Add a barrier: Use pinhole (
o=aperture=pinhole=camera center) to achieve one-to-one mapping of reality and imaging to reduce blur. The distance between the pinhole and the image plane isf(focal length); the virtual image plane is located between the pinhole and the real object, and has an inverted relationship with the image plane. - Position mapping: Use similar triangles to obtain the mapping coordinates of real coordinates on the image plane.
- Aperture: As the aperture decreases, the image becomes clearer and darker.
lens
- Concentrate multiple rays of light onto the film to increase the brightness of the image.
PS: All rays parallel to the optical axis will converge to the focus , and the distance from the focus to the center of the lens becomes the focal length; the direction of the rays passing through the center does not change.- Out of focus: The lens focuses light onto the film for a specific distance.
- Radial distortion: pincushion distortion, barrel distortion. Light rays farther away from the center of the pinhole are more bent.
camera geometry
- Points in space (with the camera aperture as the original point) are mapped to image coordinates: linear transformation is achieved using a projection matrix (fixed parameters for each camera).
- Projection matrix: represents the mapping relationship.
PS: Camera deflection: When the image coordinate system is non-vertical, the angle parameters are put into the projection matrix.
( x , y , z ) (x,y,z)(x,y,z ) Realistic coordinates,MMM is the projection matrix, whereMMThe first three columns of M are the intrinsic parameter matrix of the camera (completely determining the mapping of spatial points to image points).
Normalized projection transformation: the image coordinates are consistent with the real coordinates.
world coordinate system
A conversion that does not take the camera aperture as the starting point is nothing more than adding an extra conversion matrix.