Angles for ERDAS and Leica Photogrammetry Suite (LPS)

ERDAS, part of Leica, make software for geo-referencing aerial photos and creating a mosaic. In order to correctly geo-reference the images and create a mosaic of many images it is essential to have an inertial navigation system like the RT. This is used to measure the exact position and orientation of the camera when the photo is taken.

The RT products use a different convention for the orientation angles when compared to ERDAS. In the RT the transformation from the “world” co-ordinate frame (North, East, Down) to the aircraft frame (XYZ) uses three Euler rotations about heading, then pitch, then roll. In the ERDAS LPS software the rotations are omega (about the east axis), phi (about the inclined north axis) and finally kappa (about the inclined azimuth or yaw axis).

The latest version of the RT software can output both the usual RT angles and the angles that are suitable for the ERDAS software, omega, phi and kappa. This makes it much easier to load measurements from the RT in to the LPS software suite.