tempMat = rotationMatrix.inv() * cameraMatrix.inv() * imagePoint;

This code fragment is performing a mathematical operation involving matrix multiplication and inversion.

The variable "rotationMatrix" represents a matrix that describes a rotation transformation in three-dimensional space. The variable "cameraMatrix" represents a matrix that describes the intrinsic parameters of a camera, such as its focal length and principal point.

The variable "imagePoint" represents a point in the two-dimensional image plane of the camera, which has been measured or detected in some way.

The code first applies the inverse of the camera matrix to the image point. This effectively maps the point back into three-dimensional space, with the camera's optical center at the origin.

Then, the inverse of the rotation matrix is applied to this point. This rotates the point back to its original orientation before it was projected onto the camera's image plane.

The resulting point, stored in the "tempMat" variable, should represent the three-dimensional coordinates of the object or feature that corresponds to the original image point. This process is often used in computer vision and robotics applications for tasks such as 3D reconstruction and pose estimation.