In this paper, we describe a modern, efficient, accurate and reliable stitching algorithm that JOANNEUM RESEARCH (JR) has developed for the Phase One PAS Pana multi-camera system. The goal is to generate one large output image (four-channels including RGB and NIR) in nadir geometry. Based on the experience from a workflow developed in 2024, an improved stitching algorithm has been designed in 2025 which uses so called “controlled” projective transformations and simultaneous adjustment of all available image overlaps. We give insight into the role of projective transformations for fusing the images of calibrated cameras in a virtual image plane and how we moved on from the classical eight parameter transformation to a “controlled” transformation using only six, physically meaningful parameters. Experiments with real image data from a flight mission over Denver, USA demonstrate the accuracy and stability of the new stitching algorithm.